Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
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19-4991; 10/09
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
DS1923 temperature/humidity logger iButton® rugged, self-sufficient system that measures temperature and/or humidity records result protected memory section. recording done user-defined rate. total 8192 8-bit readings 4096 16-bit readings, taken equidistant intervals ranging from 273hr, stored. Additionally, bytes SRAM store application-specific information bytes store calibration data. mission collect data programmed begin immediately, after user-defined delay, after temperature alarm. Access memory control functions password protected. DS1923 configured communicates with host-computing device through serial 1-Wire® protocol, which requires only single data lead ground return. Every DS1923 factory lasered with guaranteed unique 64-bit registration number that allows absolute traceability. durable stainless-steel package highly resistant environmental hazards such dirt, moisture, shock. Accessories permit DS1923 mounted almost object, including containers, pallets, bags. Quick Access Alarmed Devices Through 1-Wire Conditional Search Function Bytes General-Purpose Memory Plus Bytes Calibration Memory Two-Level Password Protection Memory Configuration Registers Communicates Host with Single Digital Signal 15.4kbps Standard Speed 125kbps Overdrive Mode Using 1-Wire Protocol Individually Calibrated NIST-Traceable Chamber Calibration Coefficients Temperature Humidity Factory Programmed Into Nonvolatile (NV) Memory
DS1923
Common iButton Features
Digital Identification Information Momentary Contact Unique Factory-Lasered 64-Bit Registration Number Ensures Error-Free Device Selection Absolute Traceability Because Parts Alike Built-In Multidrop Controller 1-Wire Chip-Based Data Carrier Compactly Stores Information Data Accessed While Affixed Object Button Shape Self-Aligning with Cup-Shaped Probes Durable Stainless-Steel Case Engraved with Registration Number Withstands Harsh Environments Easily Affixed with Self-Stick Adhesive Backing, Latched Flange, Locked with Ring Pressed Onto Presence Detector Acknowledges When Reader First Applies Voltage Meets (4th Edit.); Intrinsically Safe Apparatus: Approved Under Entity Concept Class Division Group Locations
Applications
Temperature Humidity Logging Food Preparation Processing Transportation Temperature-Sensitive Humidity-Sensitive Goods, Industrial Production Warehouse Monitoring Environmental Studies/Monitoring
Features
Digital Hygrometer Measures Humidity with 8-Bit (0.6%RH) 12-Bit (0.04%RH) Resolution Operating Range: -20°C +85°C; 100%RH (see Safe Operating Range Graph) Automatically Wakes Measures Temperature and/or Humidity, Stores Values Data-Log Memory 8-Bit 16-Bit Format Digital Thermometer Measures Temperature with 8-Bit (0.5°C) 11-Bit (0.0625°C) Resolution Temperature Accuracy Better Than ±0.5°C from -10°C +65°C with Software Correction Built-In Capacitive Polymer Humidity Sensor Humidity Logging Hydrophobic Filter Protects Sensor Against Dust, Dirt, Contaminants, Water Droplets/Condensation Sampling Rate from 273hr Programmable Recording Start Delay After Elapsed Time Upon Temperature Alarm Trip Point Programmable High Trip Points Temperature Humidity Alarms
Ordering Information
PART DS1923-F5# TEMP RANGE -20°C +85°C PIN-PACKAGE iButton
#Denotes RoHS-compliant device that include lead(Pb) that exempt under RoHS requirements.
Examples Accessories
PART DS9096P DS9101 DS9093RA DS9093A DS9092 ACCESSORY Self-Stick Adhesive Multipurpose Clip Mounting Lock Ring Snap-In iButton Probe
Configuration appears data sheet.
iButton 1-Wire registered trademarks Maxim Integrated Products, Inc. Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim Direct 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
ABSOLUTE MAXIMUM RATINGS
Voltage Range Relative .-0.3V Sink Current.20mA Operating Temperature Humidity Range .-20°C +85°C, 100%RH* Storage Temperature Humidity Range .-40°C +85°C, 100%RH*
*See Safe Operating Range graph.
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VPUP +3.0V +5.25V, -20°C +85°C.)
PARAMETER PIN: GENERAL DATA 1-Wire Pullup Resistance Input Capacitance Input Load Current High-to-Low Switching Threshold Input Voltage Low-to-High Switching Threshold Switching Hysteresis Output Voltage Recovery Time (Note Rising-Edge Hold-Off Time Time-Slot Duration (Note RPUP (Notes (Note VPUP (Notes (Notes (Notes (Note (Note Standard speed, RPUP 2.2k Overdrive speed, RPUP 2.2k Overdrive speed directly prior reset pulse, RPUP 2.2k (Note Standard speed SLOT Overdrive speed, VPUP 4.5V Overdrive speed (Note Standard speed, VPUP 4.5V Standard speed (Note Overdrive speed, VPUP 4.5V Overdrive speed (Note Standard speed, VPUP 4.5V Presence-Detect High Time Standard speed (Note Overdrive speed (Note Presence-Detect Fall Time (Note Standard speed, VPUP 4.5V tFPD Standard speed Overdrive speed 0.15 63.5 0.09 SYMBOL CONDITIONS UNITS
tREC
tREH
PIN: 1-Wire RESET, PRESENCE-DETECT CYCLE
Reset Time (Note
tRSTL
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
ELECTRICAL CHARACTERISTICS (continued)
(VPUP +3.0V +5.25V, -20°C +85°C.)
PARAMETER SYMBOL CONDITIONS Standard speed, VPUP 4.5V Presence-Detect Time Standard speed (Note Overdrive speed, VPUP 4.5V (Note Overdrive speed (Note Standard speed, VPUP 4.5V tMSP Standard speed Overdrive speed PIN: 1-Wire WRITE Standard speed Write-Zero Time (Note Write-One Time (Notes PIN: 1-Wire READ Read Time (Notes Read Sample Time (Notes REAL-TIME CLOCK (RTC) Accuracy Frequency Deviation TEMPERATURE CONVERTER Conversion Time Thermal Response Time Constant Conversion Error Without Software Correction Conversion Error with Software Correction HUMIDITY CONVERTER (Note Humidity Response Time Constant Resolution Range
DS1923
71.5
1.95 1.95 1.95
UNITS
Presence-Detect Sample Time (Note
tW0L
Overdrive speed, VPUP 4.5V (Note Overdrive speed (Note Standard speed Overdrive speed Standard speed Overdrive speed Standard speed Overdrive speed
tW1L
tMSR
+25°C -20°C +85°C 8-bit mode (Note 16-bit mode bits) iButton package (Note (Notes (Notes
-300
Min/ Month
tCONV
RESP
Temperature Accuracy graph Temperature Accuracy graph
Slow moving (Note (Note (Note 0.64
0.04 0.04
Bits
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
ELECTRICAL CHARACTERISTICS (continued)
(VPUP +3.0V +5.25V, -20°C +85°C.)
PARAMETER Accuracy Interchangeability Nonlinearity Hysteresis Repeatability Long-Term Stability SYMBOL CONDITIONS With software correction (Notes With software correction (Note (Notes (Note 50%RH (Note ±0.5 %RH/ year UNITS
Note Note
Note Note Note Note Note Note Note Note Note Note Note Note Note Note Note Note Note
Note Note Note Note
System requirement. Maximum allowable pullup resistance function number 1-Wire devices system 1-Wire recovery times. specified value here applies systems with only device with minimum 1-Wire recovery times. more heavily loaded systems, active pullup such that DS2480B required. Capacitance data could 800pF when VPUP first applied. 2.2k resistor used pull data line, 2.5s after VPUP been applied, parasite capacitance does affect normal communications. function internal supply voltage. Voltage below which, during falling edge logic detected. voltage must less than equal VILMAX whenever master drives line low. Voltage above which, during rising edge logic detected. After crossed during rising edge voltage must drop detected logic characteristic linear voltages less than earliest recognition negative edge possible tREH after been previously reached. Numbers bold compliance with published iButton standards. Comparison Table. Interval during negative edge beginning presence-detect pulse between time which voltage VPUP time which voltage VPUP. Figure represents time required pullup circuitry pull voltage from VTH. Figure represents time required pullup circuitry pull voltage from input high threshold master. conserve battery power, 8-bit temperature logging whenever possible. This number derived from test conducted Cemagref Antony, France, July 2000: Test Report E42. software-corrected accuracy, assume correction using calibration coefficients with calibration equations error compensation. Software correction humidity temperature handled automatically using 1-Wire Viewer Software package available http://www.ibutton.com. Warning: sole method measuring tracking temperature and/or humidity products articles that could affect health safety persons, plants, animals, other living organisms, including limited foods, beverages, pharmaceuticals, medications, blood blood products, organs, flammable combustible products. User shall assure that redundant other primary) methods testing determining handling methods, quality, fitness articles products should implemented. Temperature and/or humidity tracking with this product, where health safety aforementioned persons things could adversely affected, only recommended when supplemental redundant information sources used. Data-logger products 100% tested calibrated time manufacture Maxim ensure that they meet data sheet parameters, including temperature accuracy. User shall responsible proper storage this product. with sensor-based product, user shall also responsible occasionally rechecking accuracy product ensure still operating properly. humidity specifications determined +25°C except where specifically indicated. Response time determined measuring point device transitions from 40%RH 90%RH 90%RH 40%RH, whichever slower. Test performed 5L/min airflow. DS1923 humidity measurements 12-bit readings. Missioning determines 8-bit 16-bit data logging. Battery lifetime same matter what resolution logged. Reliability studies have shown that device survives minimum 1000 cycles condensation drying, this product guaranteed extended condensing environments.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
ELECTRICAL CHARACTERISTICS (continued)
(VPUP +3.0V +5.25V, -20°C +85°C.) Note Software-corrected accuracy accomplished using method detailed Software Correction Algorithm Temperature section. Note Every DS1923 device measured calibrated controlled, NIST-traceable environment. Note Higher accuracy versions available. Contact factory details. Note this device exposed high humidity environment 70%RH), then exposed lower environment, device reads high period time. device typically reads within +0.5%RH 20%RH, minutes after being exposed continuous 80%RH minutes. Note capacitive sensors change their reading depending upon long they have spent high 70%RH) 20%RH). This effect called saturation drift compensated through software, described Software Saturation Drift Compensation section. Note Individual readings always include noise component (repeatability). minimize measurement error, average many samples reasonable. Note Like relative humidity sensors, when exposed contaminants and/or conditions toward limits safe operating range, accuracy degradation result (see Safe Operating Range graph). maximum long-term stability, sensor should exposed subjected organic solvents, corrosive agents (e.g., strong acids, SO2, H2SO4, CI2, HCL, H2S) strong bases (i.e., compounds with greater than Dust settling filter surface does affect sensor performance except possibly decrease speed response. more information sensor's tolerance chemicals visit:
DS1923
COMPARISON TABLE
LEGACY VALUES PARAMETER STANDARD SPEED SLOT (including tREC) tRSTL tW0L (undefined) (undefined) OVERDRIVE SPEED (undefined) DS1923 VALUES STANDARD SPEED
OVERDRIVE SPEED (undefined)
(undefined) 63.5
*Intentional change; longer recovery time requirement modified 1-Wire front-end. Note: Numbers bold compliance with published iButton standards.
iButton PHYSICAL SPECIFICATION
SIZE WEIGHT SAFETY Package Information section. grams Meets (4th Edit.); Intrinsically Safe Apparatus, approval under Entity Concept Class Division Group Locations.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Safe Operating Range
HUMIDITY (%RH) SAFE OPERATING ZONE TEMPERATURE (°C) STORAGE ONLY
Temperature Accuracy
ERROR (°C) UNCORRECTED MAXIMUM ERROR CORRECTED MAXIMUM ERROR CORRECTED MINIMUM ERROR -0.5 UNCORRECTED MINIMUM ERROR -1.0
TEMPERATURE (°C) NOTE: GRAPHS BASED 11-BIT DATA.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Minimum Lifetime Temperature, Slow Sampling (Temperature Only)
DS1923
EVERY MINUTE EVERY MINUTES 8-BIT MINIMUM PRODUCT LIFETIME (YEARS)
EVERY MINUTES SAMPLES
EVERY MINUTES OSCILLATOR
TEMPERATURE (°C)
EVERY MINUTE EVERY MINUTES 11-BIT MINIMUM PRODUCT LIFETIME (YEARS)
EVERY MINUTES EVERY MINUTES
EVERY MINUTES SAMPLES
EVERY MINUTES OSCILLATOR
TEMPERATURE (°C)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Minimum Lifetime Temperature, Fast Sampling (Temperature Only)
EVERY SECOND EVERY SECONDS
EVERY SECONDS EVERY SECONDS
EVERY SECONDS
8-BIT MINIMUM PRODUCT LIFETIME (DAYS)
TEMPERATURE (°C)
EVERY SECOND EVERY SECONDS 11-BIT MINIMUM PRODUCT LIFETIME (DAYS)
EVERY SECONDS EVERY SECONDS
EVERY SECONDS
TEMPERATURE (°C)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Minimum Lifetime Temperature, Slow Sampling (Temperature with Humidity)
EVERY MINUTE EVERY MINUTES 8-BIT TEMPERATURE PLUS HUMIDITY MINIMUM PRODUCT LIFETIME (YEARS) EVERY MINUTES SAMPLES EVERY MINUTES OSCILLATOR
DS1923
TEMPERATURE (°C)
Minimum Lifetime Temperature, Fast Sampling (Temperature with Humidity)
EVERY SECOND EVERY SECONDS 8-BIT TEMPERATURE PLUS HUMIDITY MINIMUM PRODUCT LIFETIME (DAYS) EVERY SECONDS EVERY SECONDS EVERY SECONDS
TEMPERATURE (°C)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Minimum Product Lifetime Sample Rate (Temperature Only)
+40°C +60°C 8-BIT MINIMUM PRODUCT LIFETIME (YEARS)
+75°C +85°C
0.01 0.01 MINUTES BETWEEN SAMPLES NOTE: WITH HUMIDITY LOGGING ACTIVATED, LIFETIME REDUCED LESS THAN SAMPLE RATES 3MIN. SLOWER, MAXIMUM SAMPLE RATES 1MIN. FASTER.
+40°C +60°C 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) +75°C +85°C
0.01
0.001 0.01 MINUTES BETWEEN SAMPLES NOTE: WITH HUMIDITY LOGGING ACTIVATED, LIFETIME REDUCED MAXIMUM INCREMENTAL ENERGY CONSUMED HUMIDITY LOGGING INDEPENDENT HUMIDITY LOGGING RESOLUTION.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Detailed Description
DS1923 ideal device monitor extended periods time temperature humidity object attached shipped with, such fresh produce, medical drugs supplies, refrigerators freezers, well logging climatic data during transport sensitive objects critical processes such curing. 1.27mm diameter hole device allows reach humidity sensor. rest electronics inside DS1923 sealed that exposed ambient humidity. Note that initial sealing level DS1923 achieves equivalent IP56. Aging conditions degrade integrity seal over time, applications with significant exposure liquids, sprays, other similar environments, recommended place Hygrochronunder shield protect (refer Application Note 4126: Understanding (Ingress Protection) Ratings iButton Data Loggers Capsule). hydrophobic filter protect DS1923 from destruction event full submersion liquid. Software setup data retrieval through 1-Wire interface available free download from iButton website (www.ibutton.com). This software also includes drivers serial port routines access general-purpose memory storing application-specific equipmentspecific data files. Figure shows hierarchical structure 1-Wire protocol. master must first provide eight function commands: Read ROM, Match ROM, Search ROM, Conditional Search ROM, Skip ROM, Overdrive-Skip ROM, Overdrive-Match ROM, Resume. Upon completion Overdrive-ROM command executed standard speed, device enters overdrive mode, where subsequent communication occurs higher speed. protocol required these function commands described Figure After function command successfully executed, memory control functions become accessible master provide eight available commands. protocol these memory control function commands described Figure data read written least significant first.
DS1923
Parasite Power
block diagram (Figure shows parasite-powered circuitry. This circuitry "steals" power whenever input high. provides sufficient power long specified timing voltage requirements met. advantages parasite power twofold: parasiting this input, battery power conserved, battery exhausted reason, still read.
64-Bit Lasered
Each DS1923 contains unique code that bits long. first bits 1-Wire family code. next bits unique serial number. last bits cyclic redundancy check (CRC) first bits (see Figure details). 1-Wire generated using polynomial generator consisting shift register gates shown Figure polynomial Additional information about 1-Wire available Application Note Understanding Using Cyclic Redundancy Checks with Maxim iButton Products. shift register bits initialized Then, starting with least significant family code, time shifted After family code been entered, serial number entered. After last serial number been entered, shift register contains value. Shifting bits returns shift register
Overview
block diagram Figure shows relationships between major control memory sections DS1923. device main data components: 64-bit lasered ROM; 256-bit scratchpad; 512-byte general-purpose SRAM; 256-bit register pages timekeeping, control, status, counter registers passwords; bytes calibration memory; 8192 bytes data-logging memory. Except scratchpad, other memory arranged single linear address space. data-logging memory, counter registers, several other registers read only user. Both register pages write protected while device programmed mission. password registers, read password another read/write password, only written, never read.
Hygrochron trademark Maxim Integrated Products, Inc.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
1-Wire PORT
FUNCTION CONTROL
64-BIT LASERED
PARASITE-POWERED CIRCUITRY
LITHIUM
MEMORY FUNCTION CONTROL
256-BIT SCRATCHPAD
DS1923
GENERAL-PURPOSE SRAM (512 BYTES) 32.768kHz OSCILLATOR INTERNAL TIMEKEEPING, CONTROL REGISTERS, COUNTERS
REGISTER PAGES BYTES)
THERMAL SENSE
ADC1
CALIBRATION MEMORY BYTES)
HUMIDITY SENSOR ADC2
CONTROL LOGIC
DATA-LOG MEMORY
Figure Block Diagram
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
MASTER 1-Wire OTHER DEVICES
DS1923
COMMAND LEVEL: AVAILABLE COMMANDS: READ MATCH SEARCH CONDITIONAL SEARCH SKIP RESUME OVERDRIVE-SKIP OVERDRIVE-MATCH DATA FIELD AFFECTED: 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG, ALARM FLAGS, SEARCH CONDITIONS RC-FLAG RC-FLAG RC-FLAG, OD-FLAG 64-BIT ROM, RC-FLAG, OD-FLAG
1-Wire FUNCTION COMMANDS
DS1923-SPECIFIC MEMORY/CONTROL FUNCTION COMMANDS
WRITE SCRATCHPAD READ SCRATCHPAD COPY SCRATCHPAD WITH READ MEMORY WITH CLEAR MEMORY WITH FORCED CONVERSION START MISSION WITH STOP MISSION WITH
256-BIT SCRATCHPAD, FLAGS 256-BIT SCRATCHPAD 512-BYTE DATA MEMORY, REGISTERS, FLAGS, PASSWORDS MEMORY, REGISTERS, PASSWORDS MISSION TIMESTAMP, MISSION SAMPLES COUNTER, START DELAY, ALARM FLAGS, PASSWORDS MEMORY ADDRESSES 020Ch 020Fh FLAGS, TIMESTAMP, MEMORY ADDRESSES 020Ch 020Fh (WHEN LOGGING) FLAGS
Figure Hierarchical Structure 1-Wire Protocol
8-BIT CODE 48-BIT SERIAL NUMBER 8-BIT FAMILY CODE (41h)
Figure 64-Bit Lasered
POLYNOMIAL
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
INPUT DATA
Figure 1-Wire Generator
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Memory
Figure shows DS1923 memory map. Pages contain bytes general-purpose SRAM. various registers control device fill pages called register pages (see Figure details). Pages used storage space calibration data. data-log logging memory starts address 1000h (page 128) extends over pages. memory pages reserved future extensions. scratchpad additional page that acts buffer when writing SRAM memory register pages. calibration memory holds data from device calibration that used further improve accuracy temperature humidity readings. Software Correction Algorithm sections details. last byte calibration memory page stores 8-bit preceding bytes. Page exact copy data page While user overwrite calibration memory, this recommended. Security Password section ways protect memory. access type register pages register-specific depends whether device programmed mission. Figure shows details. data-log memory read only user. written solely under supervision on-chip control logic. special behavior write access logic (write scratchpad, copy scratchpad), recommended only write full pages time. This also applies register pages. Address Registers Transfer Status section details.
32-BYTE INTERMEDIATE STORAGE SCRATCHPAD ADDRESS 0000h 001Fh 0020h 01FFh 0200h 021Fh 0220h 023Fh 0240h 025Fh 0260h 027Fh 0280h 0FFFh 1000h 2FFFh 32-BYTE GENERAL-PURPOSE SRAM (R/W) GENERAL-PURPOSE SRAM (R/W) 32-BYTE REGISTER PAGE 32-BYTE REGISTER PAGE CALIBRATION MEMORY PAGE (R/W) CALIBRATION MEMORY PAGE (R/W) (RESERVED FUTURE EXTENSIONS) DATA-LOG MEMORY (READ ONLY) PAGE PAGES PAGE PAGE PAGE PAGE PAGES PAGES
Figure Memory
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
ADDRESS 0200h 0201h 0202h 0203h 0204h 0205h 0206h 0207h 0208h 0209h 020Ah 020Bh 020Ch 020Dh 020Eh 020Fh 0210h Byte CENT 12/24 Years Byte High Byte Threshold High Threshold Threshold High Threshold High Byte Byte High Byte ETHA ETLA Seconds Minutes Hour AM/PM Hour FUNCTION ACCESS* Single Seconds Single Minutes Single Hours Single Date Single Months Single Years Sample Rate Temperature Alarms Humidity Alarms Latest Temperature Latest Humidity Temperature Alarm Enable Humidity Alarm Enable Control Mission Control Alarm Status General Status Start Delay Counter RealTime Clock Registers
Date Months
0211h 0212h 0213h 0214h 0215h 0216h 0217h 0218h
SUTA
WFTA
HLFS MEMCLR
TLFS
EHHA EHSS
EHLA EOSC
Byte Center Byte High Byte
*The left entry ACCESS column valid between missions. right entry shows applicable access type while mission progress.
Figure Register Pages
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
ADDRESS 0219h 021Ah 021Bh 021Ch 021Dh 021Eh 021Fh 0220h 0221h 0222h 0223h 0224h 0225h 0226h 0227h 0228h 022Fh 0230h 0237h 0238h 023Fh function; these bytes read 00h) CENT 12/24 Years Function; Reads 00h) Byte Center Byte High Byte Byte Center Byte High Byte Configuration Code First Byte Eighth Byte First Byte Eighth Byte Seconds Minutes Hour AM/PM Hour FUNCTION ACCESS* Single Seconds Single Minutes Single Hours Single Date Single Months Single Years Mission Samples Counter Device Samples Counter Flavor Control Read Access Password Full Access Password Mission Timestamp
Date Months
*The left entry ACCESS column valid between missions. right entry shows applicable access type while mission progress.
Figure Register Pages (continued)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Detailed Register Descriptions
Timekeeping Calendar
calendar information accessed reading/writing appropriate bytes register page, address 0200h 0205h. readings valid, registers must read sequentially starting address 0200h. Some bits These bits always read regardless they written. number representation registers binary-coded decimal (BCD) format. DS1923's either 12hr 24hr mode. Hours register (address 0202h) defined 12hr 24hr mode select bit. When high, 12hr mode selected. 12hr mode, AM/PM with logic being 24hr mode, 20hr (20hr 23hr). CENT bit, Months register, written user. This changes state when years counter transitions from calendar logic designed automatically compensate leap years. every year value that either multiple device adds 29th February. This works correctly (but including) year 2100.
Sample Rate
content Sample Rate register (addresses 0206h, 0207h) specifies time elapse seconds EHSS minutes EHSS between temperature/humidity-logging events. sample rate value from 16,383, coded unsigned 14-bit binary number. EHSS shortest time between logging events longest (sample rate 3FFFh) 4.55hr. EHSS shortest 1min longest time 273.05hr (sample rate 3FFFh). EHSS located Control register address 0212h. important that user sets EHSS accordingly while setting Sample Rate register. Writing sample rate 0000h results sample rate 0001h, causing DS1923 temperature either every minute every second depending upon state EHSS bit.
DS1923
Registers Bitmap
ADDRESS 0200h 0201h 0202h 0203h 0204h 0205h CENT 12/24 Years Seconds Minutes Hour AM/PM Hour Single Seconds Single Minutes Single Hours Single Date Single Months Single Years
Date Months
Note: During mission, there only read access these registers. cells marked always read cannot written
Sample Rate Register Bitmap
ADDRESS 0206h 0207h Sample Rate Sample Rate High
Note: During mission, there only read access these registers. cells marked always read cannot written
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Temperature Conversion
DS1923's temperature range begins -20°C ends +85°C. Temperature values represented 8-bit 16-bit unsigned binary number with resolution 0.5°C 8-bit mode 0.0625°C 16-bit mode. higher temperature byte always valid. 16-bit mode, only three highest bits lower byte valid. five lower bits read undefined device 8-bit temperature mode. out-of-range temperature reading indicated 0000h when cold FFE0h when hot. With representing decimal equivalent temperature reading, temperature value calculated (°C) TRH/2 TRL/512 (16-bit mode, TLFS address 0213h) (°C) TRH/2 (8-bit mode, TLFS address 0213h) This equation valid converting temperature readings stored data-log memory well data read from Latest Temperature Conversion Result register. specify temperature alarm thresholds, previous equations resolved TALM (°C) Because temperature alarm threshold only byte, resolution temperature increment limited 0.5°C. TALM value must converted into hexadecimal format before written Temperature Alarm Threshold registers (Low Alarm address 0208h; High Alarm address 0209h). Independent conversion mode (8-bit 16-bit), only most significant byte temperature conversion used determine whether alarm generated.
Humidity Conversion
addition temperature, DS1923 humidity data 8-bit 16-bit format. Humidity values represented 8-bit 16-bit unsigned binary numbers with resolution 0.64%RH 8-bit mode 0.04%RH 16-bit mode. DS1923 reads data from humidity sensor whenever Forced Conversion command executed (see Memory/Control Function Commands section) during mission device humidity data. Regardless setup, DS1923 always reads bits from humidity sensor. result latest humidity reading found address 020Eh (low byte) 020Fh (high byte). most significant read from humidity sensor always found address 020Fh. 12-bit digital output humidity sensor, lower bits 16-bit format undefined.
Latest Temperature Conversion Result Register Bitmap
ADDRESS 020Ch 020Dh BYTE
Table Temperature Conversion Examples
MODE 8-Bit 8-Bit 16-Bit 16-Bit DECIMAL DECIMAL (°C) -29.5 1.000 -29.3125
Table Temperature Alarm Threshold Examples
(°C) 25.5 -10.0 TALM DECIMAL
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Latest Humidity Conversion Result Register Bitmap
ADDRESS 020Eh 020Fh BYTE
DS1923
During mission, humidity logging enabled, byte (H11 always recorded. byte only recorded DS1923 16-bit humidity logging. logging mode (8-bit 16-bit) selected through HLFS Mission Control register, address 0213h.
16-BIT MODE, HLFS IVAL (HRH HRL)/16 Round IVAL down nearest integer; this eliminates undefined bits HRL. ADVAL IVAL 5.02/4096
With representing decimal equivalent humidity reading, actual humidity calculated according algorithms shown table below.
8-BIT MODE, HLFS (N/A) ADVAL 5.02/256
HUMIDITY(%RH) (ADVAL 0.958)/0.0307
result humidity reading that needs corrected achieve specified accuracy. Software Correction Algorithm Humidity section further details. specify humidity alarm thresholds, equation needs resolved ADVAL HUMIDITY(%RH) 0.0307 0.958 HALM ADVAL 256/5.02 Round HALM nearest integer. HALM value needs converted into hexadecimal before written Humidity Alarm Threshold registers (Low Alarm address 020Ah; High Alarm address 020Bh). Independent conversion
mode (8-bit 16-bit), only most significant byte humidity conversion used determine whether alarm generated. alarm thresholds applied humidity readings. Therefore, software correction used, effect software correction reversed before calculating humidity alarm threshold. example, desired alarm threshold 60%RH. threshold correspond reading 65%RH (i.e., before correction). 60%RH (after correction) threshold, HALM value then needs calculated 65%RH. These examples include effects software correction.
Table Humidity Conversion Examples
MODE 8-bit 8-bit 16-bit 16-bit DECIMAL DECIMAL HUMIDITY (%RH) 84.41 34.59 84.89 34.70
Table Humidity Alarm Threshold Examples
HUMIDITY (%RH) HALM DECIMAL
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Temperature Sensor Control Register Bitmap
ADDRESS 0210h ETHA ETLA
Note: During mission, there only read access this register. Bits have function. They always read cannot written
Humidity Sensor Control Register Bitmap
ADDRESS 0211h EHHA EHLA
Note: During mission, there only read access this register. Bits have function. They always read cannot written
Control Register Bitmap
ADDRESS 0212h EHSS EOSC
Note: During mission, there only read access this register. Bits have function. They always read cannot written
Temperature Sensor Alarm
DS1923 Temperature Alarm Threshold registers (address 0208h, 0209h) store values that determine whether critical temperature been reached. temperature alarm generated device measures alarming temperature alarm signaling enabled. bits ETLA ETHA that enable temperature alarm located Temperature Sensor Control register. temperature alarm flags found Alarm Status register address 0214h. Enable Temperature High Alarm (ETHA). This controls whether, during mission, temperature high alarm flag (THF) set, temperature conversion results value equal higher than value Temperature High Alarm Threshold register. ETHA temperature high alarms enabled. ETHA temperature high alarms generated. Enable Temperature Alarm (ETLA). This controls whether, during mission, temperature alarm flag (TLF) set, temperature conversion results value equal lower than value Temperature Alarm Threshold register. ETLA temperature alarms enabled. ETLA temperature alarms generated.
alarm signaling enabled. bits EHLA EHHA that enable humidity alarm located Humidity Sensor Control register. corresponding alarm flags found Alarm Status register address 0214h. Enable Humidity High Alarm (EHHA). This controls whether, during mission, humidity high alarm flag (HHF) set, value from humidity sensor equal higher than value Humidity High Alarm Threshold register. EHHA humidity high alarms enabled. EHHA humidity high alarms generated. Enable Humidity Alarm (EHLA). This controls whether, during mission, humidity alarm flag (HLF) set, value from humidity sensor equal lower than value Humidity Alarm Threshold register. EHLA humidity alarms enabled. EHLA humidity alarms generated.
Control
minimize power consumption DS1923, oscillator should turned when device use. oscillator on/off located Control register. This register also includes EHSS bit, which determines whether sample rate specified seconds minutes. Enable High-Speed Sample (EHSS). This controls speed sample rate counter. When logic sample rate specified minutes. When logic sample rate specified seconds.
Humidity Alarm
DS1923 Humidity Alarm Threshold registers (address 020Ah, 020Bh) store values that determine whether humidity readings generate alarm. Such alarm generated humidity data read from sensor qualifies alarm
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Enable Oscillator (EOSC). This controls crystal oscillator RTC. When logic oscillator starts. When written logic oscillator stops device low-power data-retention mode. This must normal operation. Forced Conversion Start Mission command automatically starts changing EOSC logic ning, overwriting previously collected data. this logging conversions stop once data-log memory full. However, continues remains until Stop Mission command performed. Humidity Logging Format Selection (HLFS). This specifies format used store humidity readings data-log memory. this data stored 8-bit format. this 16-bit format used (higher resolution). With 16-bit format, most significant byte stored lower address. Temperature Logging Format Selection (TLFS). This specifies format used store temperature readings data-log memory. this data stored 8-bit format. this 16-bit format used (higher resolution). With 16-bit format, most significant byte stored lower address. Enable Humidity Logging (EHL). DS1923 humidity-logging mission, this must logic temperature humidity logging enabled, recorded humidity values begin address 2000h (TLFS HLFS) 1A00h (TLFS HLFS 2400h (TLFS HLFS only humidity logging enabled, recorded values stored starting address 1000h. Since humidity data little scientific value without knowing temperature, typically both humidity temperature logging enabled (i.e., Enable Temperature Logging (ETL). device temperature-logging mission, this must logic successfully start mission, must temperature logging enabled, recorded temperature values always stored starting address 1000h.
DS1923
Mission Control
DS1923 operation writing appropriate data special function registers, which located register pages. settings Mission Control register determine whether temperature and/or humidity logged, which format bits) applies, whether data overwritten data once data-log memory full. additional control tell DS1923 wait with logging data until temperature alarm encountered. Start Mission Upon Temperature Alarm (SUTA). This specifies whether mission begins immediately (includes delayed start) temperature alarm required start mission. this device performs 8-bit temperature conversion selected sample rate begins with data logging only alarming temperature (high alarm alarm) found. first logged temperature when alarm occurred. However, Mission Sample Counter does increment. start upon temperature alarm function only available temperature logging enabled (ETL Rollover Control (RO). This controls whether, during mission, data-log memory overwritten with data whether data logging stopped once data-log memory full. Setting this enables rollover data logging continues begin-
Mission Control Register Bitmap
ADDRESS 0213h SUTA HLFS TLFS
Note: During mission, there only read access this register. Bits have function. They always read cannot written
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Alarm Status Register Bitmap
ADDRESS 0214h
Note: There only read access this register. Bits have function. They always read five alarm status bits cleared simultaneously when Clear Memory command invoked. Memory Control Functions section details.
General Status Register Bitmap
ADDRESS 0215h WFTA MEMCLR
Note: There only read access this register. Bits have function.
Alarm Status
fastest determine whether programmed temperature humidity threshold exceeded during mission through reading Alarm Status register. networked environment that contains multiple DS1923 iButtons, devices that encountered alarm quickly identified means Conditional Search command (see 1-Wire Function Commands section). humidity temperature alarm only occurs enabled (see Temperature Sensor Alarm Humidity Alarm sections). alarm always enabled. Battery-On Reset Alarm (BOR). this reads device performed power-on reset. This indicates that device experienced shock enough interrupt internal battery power supply. device still appear functional, lost factory calibration. data found data-log memory should disregarded. Humidity High Alarm Flag (HHF). this reads there least humidity reading during mission revealing value equal higher than value Humidity High Alarm register. forced conversion affect bit. Humidity Alarm Flag (HLF). this reads there least humidity reading during mission revealing value equal lower than value Humidity Alarm register. forced conversion affect bit. Temperature High Alarm Flag (THF). this reads there least temperature conversion during mission revealing temperature equal higher than value Temperature High Alarm register. forced conversion affect bit. This also with initial alarm SUTA mode. Temperature Alarm Flag (TLF). this reads there least temperature conversion
during mission revealing temperature equal lower than value Temperature Alarm register. forced conversion affect bit. This also with initial alarm SUTA mode.
General Status
information General Status register tells host computer whether mission-related command executed successfully. Individual status bits indicate whether DS1923 performing mission, waiting temperature alarm trigger logging data whether data from latest mission been cleared. Waiting Temperature Alarm (WFTA). this reads mission start upon temperature alarm selected Start Mission command successfully executed, device experienced temperature alarm. This cleared after temperature alarm event, affected Clear Memory command. Once set, WFTA remains mission stopped before temperature alarm occurs. clear WFTA manually before starting mission, high temperature alarm (address 0209h) -40°C perform forced conversion. Memory Cleared (MEMCLR). this reads Mission Timestamp, Mission Samples Counter, alarm flags Alarm Status register have been cleared preparation mission. Executing Clear Memory command clears these memory sections. MEMCLR returns soon mission started using Start Mission command. memory must cleared mission start. Mission Progress (MIP). this reads device been mission this mission still progress. returns from logic logic when mission ended. Start Mission with Password Stop Mission with Password sections.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Mission Start Delay Counter Register Bitmap
ADDRESS 0216h 0217h 0218h Delay Byte Delay Center Byte Delay High Byte
DS1923
Note: During mission, there only read access this register.
Mission Timestamp Register Bitmap
ADDRESS 0219h 021Ah 021Bh 021Ch 021Dh 021Eh CENT 12/24 Years Seconds Minutes Hours AM/PM Hours Single Seconds Single Minutes Single Hours Single Date Single Months Single Years
Date Months
Note: There only read access this register.
ADDRESS 0220h 0221h 0222h
Mission Samples Counter Register Bitmap
Byte Center Byte High Byte
Note: There only read access this register. Note that when both internal temperature humidity logging enabled, readings counted event Mission Sample Counter Device Sample Counter.
Mission Start Delay
content Mission Start Delay Counter register tells many minutes must expire from time mission started until first measurement mission takes place (SUTA until device starts testing temperature temperature alarm (SUTA Mission Start Delay register stored unsigned 24-bit integer number. maximum delay 16,777,215min, equivalent 11,650 days roughly 31yr. start delay nonzero SUTA first delay must expire before device starts testing temperature alarms begin logging data. typical mission, Mission Start Delay mission long single DS1923 store readings selected sample rate, several devices Mission Start Delay second device start recording soon memory first device full, Mission Control register (address 0213h) must prevent overwriting collected data once data-log memory full.
Mission Timestamp
Mission Timestamp register indicates date time first temperature humidity sample mission. There only read access Mission Timestamp register.
Mission Progress Indicator
Depending settings Mission Control register (address 0213h), DS1923 logs temperature and/or humidity 8-bit 16-bit format. description explains where device stores data data-log memory. Mission Samples Counter register together with starting address logging format bits) provide information identify valid blocks data that have been gathered during current (MIP latest mission (MIP Data-Log Memory Usage section illustration. Note that when SUTA Mission Samples Counter does increment when first sample logged. number read from Mission Samples Counter indicates often DS1923 woke during mission measure temperature and/or humidity. number format 24-bit unsigned integer. Mission Samples Counter reset through Clear Memory command.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Device Samples Counter Register Bitmap
ADDRESS 0223h 0224h 0225h Byte Center Byte High Byte
Note: There only read access this register.
Device Configuration Register Bitmap
ADDRESS 0226h PART DS2422 DS1923 DS1922L DS1922T DS1922E
Note: There only read access this register.
Password Control Register Bitmap
ADDRESS 0227h
Note: During mission, there only read access this register.
Other Indicators
Device Samples Counter register similar Mission Samples Counter register. During mission this counter increments whenever DS1923 wakes measure data when device testing temperature alarm SUTA mode. Between missions, counter increments whenever Forced Conversion command executed. This Device Samples Counter register functions like gauge battery that powers iButton. Device Samples Counter register reset zero when iButton assembled. counter increments couple times during final test. number format 24-bit unsigned integer. maximum number that represented this format 16,777,215. code Device Configuration register allows master distinguish between DS2422 chip different versions DS1922 iButtons. Device Configuration Register table shows codes assigned various devices.
Security Password
DS1923 designed passwords that control read access full access. Reading from writing scratchpad well Forced Conversion command does require password. password must transmitted immediately after command code memory control function. password checking enabled, password transmitted compared passwords stored device. data pattern stored Password Control register determines whether password checking enabled. enable password checking, bits need form binary pattern 10101010 (AAh). default pattern different from AAh. pattern different from AAh, pattern accepted long length exactly bits. Once enabled, changing passwords disabling password checking requires knowledge current fullaccess password.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Read-Access Password Register Bitmap
ADDRESS 0228h 0229h 022Eh 022Fh RP55 RP63 RP54 RP62 RP53 RP61 RP52 RP60 RP15 RP14 RP13 RP12 RP51 RP59 RP50 RP58 RP49 RP57 RP48 RP56 RP11 RP10
DS1923
Note: There only write access this register. Attempting read password reports zeros. password cannot changed while mission progress.
Full-Access Password Register Bitmap
ADDRESS 0230h 0231h 0236h 0237h FP55 FP63 FP54 FP62 FP53 FP61 FP52 FP60 FP15 FP14 FP13 FP12 FP51 FP59 FP50 FP58 FP49 FP57 FP48 FP56 FP11 FP10
Note: There only write access this register. Attempting read password reports zeros. password cannot changed while mission progress.
Before enabling password checking, passwords read-only access well full access (read/write/control) must written password registers. Setting password enabling/disabling password checking done same writing data memory location; only address different. Since they located same memory page, both passwords redefined same time. Read Access Password must transmitted exactly sequence RP0, RP1.RP62, RP63. This password only applies Read Memory with command. DS1923 delivers requested data only password transmitted master correct password checking enabled.
Full Access Password must transmitted exactly sequence FP0, FP1.FP62, FP63. affects commands Read Memory with CRC, Copy Scratchpad, Clear Memory, Start Mission, Stop Mission. DS1923 executes command only password transmitted master correct password checking enabled. special behavior write-access logic, Password Control register both passwords must written same time. When setting passwords, always verify (read back) scratchpad before sending Copy Scratchpad command. After password successfully copied from scratchpad memory location, erase scratchpad filling with data (Write Scratchpad command). Otherwise, copy passwords remains scratchpad public read access.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Data-Log Memory Usage
Once mission, DS1923 logs temperature and/or humidity measurements equidistant time points entry after entry data-log memory. data-log memory store 8192 entries 8-bit format 4096 entries 16-bit format (Figure 7a). temperature well humidity logged, both same format, memory split into equal sections that store 4096 8-bit entries 2048 16-bit entries (Figure 7b). device data different formats, temperature 8-bit humidity 16-bit format, memory split into blocks different size, accommodating 2560 entries either data source (Figure 7c). this case, upper bytes used. 16-bit format, higher bits entry stored lower address. Knowing starting time point (Mission Timestamp) interval between temperature measurements, reconstruct time date each measurement. There alternatives DS1923 behaves after data-log memory filled with data. user program device either stop further recording (disable rollover) overwrite previously recorded data (enable rollover), entry time, starting again beginning respective memory section. contents Mission Samples Counter conjunction with sample rate Mission Timestamp allow reconstructing time points values stored data-log memory. This gives exact history over time most recent measurements taken. Earlier measurements cannot reconstructed. alarm signaling desired, temperature alarm and/or humidity alarm high thresholds must defined. Temperature Conversion section information convert temperature value into binary code written threshold registers. Humidity Conversion section information determining thresholds humidity alarm. addition, temperature alarm and/or humidity alarm must enabled and/or high threshold. This makes device respond Conditional Search command (see the1-Wire Function Commands section), provided that alarming condition been encountered. setting (rollover enable) sample rate depends duration mission monitoring requirements. most recently logged data important, rollover should enabled Otherwise should estimate duration mission minutes divide number 8192 (single channel 8-bit format) 4096 (single channel 16-bit format, channels 8-bit format) 2048 (two channels 16-bit format) 2560 (two channels, 8-bit 16-bit format) calculate value sample rate (number minutes between conversions). estimated duration mission days 14400min), example, then 8192-byte capacity data-log memory would sufficient store 8-bit value every 1.8min (110s). data-log memory DS1923 large enough store readings, several devices Mission Start Delay values that make second device start logging soon memory first device full, RO-bit needs disable rollover that would otherwise overwrite logged data. After Mission Start Delay set, sample rate must written Sample Rate register. sample rate value from 16,383, coded unsigned 14-bit binary number. fastest sample rate sample second (EHSS sample rate 0001h) slowest sample every 273.05hr (EHSS sample rate 3FFFh). sample every 6min, example, sample rate value must (EHSS decimal (equivalent 0168h EHSS there risk unauthorized access DS1923 manipulation data, should define passwords read access full access. Before passwords become effective, their must enabled. Security Password section more details.
Missioning
typical task DS1923 iButton recording temperature and/or humidity. Before device perform this function, needs properly. This procedure called missioning. First, DS1923 must have valid time date. This reference time local time, when used inside mobile unit, (also called GMT, Greenwich Mean Time), other time standard that agreed upon. oscillator must running (EOSC memory assigned store Mission Timestamp, Mission Samples Counter, alarm flags must cleared using Memory Clear command. enable device mission, least enable logging bits (ETL, EHL) must These general settings that must made case, regardless type object monitored duration mission.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
TLFS HLFS 8192 8-BIT ENTRIES TEMPERATURE HUMIDITY DATA 1000h TLFS HLFS 4096 16-BIT ENTRIES TEMPERATURE HUMIDITY DATA 1000h WITH 16-BIT FORMAT, MOST SIGNIFICANT BYTE STORED LOWER ADDRESS. 2FFFh
2FFFh
Figure 1-Channel Logging
TLFS HLFS 1000h TEMPERATURE 4096 8-BIT ENTRIES 1FFFh 2000h HUMIDITY DATA 4096 8-BIT ENTRIES 2FFFh
TLFS HLFS 1000h TEMPERATURE 2048 16-BIT ENTRIES 1FFFh 2000h HUMIDITY DATA 2048 16-BIT ENTRIES 2FFFh WITH 16-BIT FORMAT, MOST SIGNIFICANT BYTE STORED LOWER ADDRESS.
Figure 2-Channel Logging, Equal Resolution
TLFS HLFS TEMPERATURE 2560 8-BIT ENTRIES 1000h
TLFS HLFS 1000h TEMPERATURE 2560 16-BIT ENTRIES 23FFh HUMIDITY DATA 2560 8-BIT ENTRIES 2400h
19FFh 1A00h
HUMIDITY DATA 2560 16-BIT ENTRIES 2DFFh 2E00h (NOT USED) 2FFFh
WITH 16-BIT FORMAT, MOST SIGNIFICANT BYTE STORED LOWER ADDRESS.
2DFFh 2E00h
(NOT USED) 2FFFh
Figure 2-Channel Logging, Different Resolution
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
last step begin mission issue Start Mission command. soon received this command, DS1923 sets flag clears MEMCLR flag. With immediate/delayed start mode (SUTA after many minutes specified Mission Start Delay over, device wakes copies current date time Mission Timestamp register, logs first entry mission. This increments both Mission Samples Counter Device Samples Counter. subsequent entries made specified value Sample Rate register EHSS bit. start upon temperature alarm mode chosen (SUTA temperature logging enabled (ETL DS1923 first waits until start delay over. Then device wakes intervals specified sample rate EHSS measures temperature. This increments Device Samples Counter register only. first sample mission logged when temperature alarm occurred. However, Mission Sample Counter does increment. sample period later Mission Timestamp register set. From then both Mission Samples Counter Device Samples Counter registers increment same time. subsequent entries made specified value Sample Rate register EHSS bit. general-purpose memory operates independently other memory sections write protected during mission. DS1923's memory read
DS1923
time, e.g., watch progress mission. Attempts read passwords read bytes instead data that stored password registers.
Memory Access
Address Registers Transfer Status
Because serial data transfer, DS1923 employs three address registers called TA1, TA2, (Figure Registers must loaded with target address which data written from which data sent master upon Read command. Register acts like byte counter transfer status register. used verify data integrity with Write commands. Therefore, master only read access this register. lower bits register indicate address last byte that been written scratchpad. This address called ending offset. DS1923 requires that ending offset always Copy Scratchpad function. register, called partial byte flag, number data bits sent master integer multiple always Note that lowest bits target address also determine address within scratchpad, where intermediate storage data begins. This address called byte offset. target address Write command 13Ch, example, scratchpad stores incoming data beginning byte offset full after only bytes. corresponding ending offset this example 1Fh. best economy speed
NUMBER TARGET ADDRESS (TA1)
TARGET ADDRESS (TA2)
ENDING ADDRESS WITH DATA STATUS (E/S) (READ ONLY)
Figure Address Registers
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
efficiency, target address writing should point beginning page, i.e., byte offset Thus, full 32-byte capacity scratchpad available, resulting also ending offset 1Fh. ending offset together with flag means support master checking data integrity after Write command. highest valued register, called authorization accepted (AA), indicates that valid Copy command scratchpad been received executed. Writing data scratchpad clears this flag.
Memory Control Function Commands
Figure shows protocols necessary accessing memory special function registers DS1923. example these other functions DS1923 mission included Mission Example: Prepare Start Mission section. communication between master DS1923 takes place either standard speed (default, overdrive speed explicitly into overdrive mode, DS1923 assumes standard speed. Internal memory access during mission priority over external access through 1-Wire interface. This affects several commands this section. Memory Access Conflicts section details solutions.
DS1923
Writing with Verification
write data DS1923, scratchpad must used intermediate storage. First, master issues Write Scratchpad command specify desired target address, followed data written scratchpad. next step, master sends Read Scratchpad command read scratchpad verify data integrity. preamble scratchpad data, DS1923 sends requested target address contents Register. flag set, data arrive correctly scratchpad. master does need continue reading; start trial write data scratchpad. Similarly, flag indicates that Write command recognized device. everything went correctly, both flags cleared ending offset indicates address last byte written scratchpad. master continue verifying every data bit. After master verified data, must send Copy Scratchpad command. This command must followed exactly data three address registers TA1, TA2, E/S, master read them verifying scratchpad. soon DS1923 received these bytes, copies data requested location beginning target address.
Write Scratchpad [0Fh]
After issuing Write Scratchpad command, master must first provide 2-byte target address, followed data written scratchpad. data written scratchpad starting byte offset T[4:0]. master must send many bytes needed reach ending offset 1Fh. data byte incomplete, content ignored partial byte flag set. When executing Write Scratchpad command, generator inside DS1923 calculates entire data stream, starting command code ending last data byte sent master (Figure 15). This generated using CRC-16 polynomial first clearing generator then shifting command code (0Fh) Write Scratchpad command, target addresses supplied master, data bytes. ending offset 11111b, master send read time slots receive inverted CRC-16 generated DS1923. Note that both register pages write protected during mission. Although Write Scratchpad command works normally time, subsequent copy scratchpad register page fails during mission.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Read Scratchpad [AAh]
This command used verify scratchpad data target address. After issuing Read Scratchpad command, master begins reading. first bytes target address. next byte ending offset/data status byte (E/S) followed scratchpad data beginning byte offset T[4:0], shown Figure master continue reading data until scratchpad after which receives inverted CRC-16 command code, target addresses TA2, byte, scratchpad data starting target address. After read, master reads logic from DS1923 until reset pulse issued. progress, write attempts register pages successful. remaining indicates this.
Read Memory with Password [69h]
Read Memory with command general function read from device. This command generates transmits 16-bit following last data byte memory page. After having sent command code Read Memory with command, master sends 2-byte address that indicates starting byte location. Next, master must transmit 64-bit passwords. passwords enabled transmitted password does match stored passwords, Read Memory with Password command fails. device stops communicating waits reset pulse. password correct passwords were enabled, master reads data from DS1923 beginning from starting address continuing until 32-byte page reached. that point master sends additional readdata time slots receives inverted 16-bit CRC. With subsequent read-data time slots master receives data starting beginning next memory page followed again that page. This sequence continues until master resets device. When trying read passwords memory areas that marked "reserved," DS1923 transmits bytes, respectively. 32-byte memory page based data transmitted. With initial pass through Read Memory with flow, 16-bit value result shifting command byte into cleared generator followed address bytes contents data memory. Subsequent passes through Read Memory with flow generate 16-bit that result clearing generator then shifting contents data memory page. After 16-bit last page read, master receives logic from DS1923 until reset pulse issued. Read Memory with command sequence ended point issuing reset pulse.
Copy Scratchpad with Password [99h]
This command used copy data from scratchpad writable memory sections. After issuing Copy Scratchpad command, master must provide 3-byte authorization pattern, which obtained reading scratchpad verification. This pattern must exactly match data contained three address registers (TA1, TA2, E/S, that order). Next, master must transmit 64-bit full access password. passwords enabled transmitted password different from stored full access password, Copy Scratchpad with Password command fails. device stops communicating waits reset pulse. password correct passwords were enabled, device tests 3-byte authorization code. authorization code pattern matches, flag copy begins. pattern alternating transmitted after data been copied until master issues reset pulse. While copy progress, attempt reset part ignored. Copy typically takes byte. data copied determined three address registers. scratchpad data from beginning offset through ending offset copied, starting target address. flag remains logic until cleared next Write Scratchpad command. With suitable password, copy scratchpad always functions pages data memory pages calibration memory. While mission
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
MASTER MEMORY CONTROL FUNCTION COMMAND FROM FUNCTIONS FLOWCHART (FIGURE
WRITE SCRATCHPAD? MASTER [T7:T0]
READ SCRATCHPAD? MASTER [T7:T0]
COPY SCRATCHPAD [WITH MASTER [T7:T0], [T15:T8]
FIGURE
AUTHORIZATION CODE MASTER [T15:T8] MASTER [T15:T8] MASTER BYTE
DS1923 SETS SCRATCHPAD OFFSET [T4:T0] CLEARS (PF,
MASTER ENDING OFFSET WITH DATA STATUS (E/S)
MASTER BITS [PASSWORD]
MASTER DATA BYTE SCRATCHPAD OFFSET
DS1923 SETS SCRATCHPAD OFFSET [T4:T0]
PASSWORD ACCEPTED?
DS1923 INCREMENTS SCRATCHPAD OFFSET
DS1923 SETS [E4:E0] SCRATCHPAD OFFSET
DS1923 INCREMENTS SCRATCHPAD OFFSET
MASTER DATA BYTE FROM SCRATCHPAD OFFSET
AUTHORIZATION CODE MATCH?
MASTER RESET?
MASTER RESET?
SCRATCHPAD OFFSET 11111b? PARTIAL BYTE WRITTEN?
SCRATCHPAD OFFSET 11111b? MASTER CRC-16 COMMAND, ADDRESS DATA, BYTE, DATA STARTING TARGET ADDRESS MASTER "1"s
DS1923 COPIES SCRATCHPAD DATA MEMORY
MASTER "1"s COPYING FINISHED DS1923 MASTER RESET?
MASTER RESET?
MASTER CRC-16 COMMAND, ADDRESS DATA MASTER RESET? MASTER RESET? MASTER "1"s MASTER "1"s
MASTER RESET? DS1923
MASTER RESET?
FROM FIGURE FUNCTIONS FLOWCHART (FIGURE
Figure Memory/Control Function Flowchart
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
FROM FIGURE
READ MEMORY [WITH MASTER [T7:T0], [T15:T8]
CLEAR MEMORY [WITH MASTER BITS [PASSWORD]
FORCED CONVERSION? MASTER DUMMY BYTE
FIGURE
DECISION MADE DS1923
MASTER BITS [PASSWORD]
MASTER DUMMY BYTE
MISSION PROGRESS?
PASSWORD ACCEPTED? DECISION MADE MASTER DS1923 SETS MEMORY ADDRESS [T15:T0]
PASSWORD ACCEPTED?
DS1923 PERFORMS TEMPERATURE CONVERSION
MISSION PROGRESS? DS1923 CLEARS MISSION TIMESTAMP, MISSION SAMPLES COUNTER, ALARM FLAGS
DS1923 COPIES RESULT ADDRESS 020C/Dh
MASTER DATA BYTE FROM MEMORY ADDRESS
DS1923 PERFORMS HUMIDITY CONVERSION
MASTER RESET?
DS1923 INCREMENTS ADDRESS COUNTER
DS1923 COPIES RESULT ADDRESS 020E/Fh
DS1923 SETS MEMCLR MASTER RESET? MASTER RESET?
PAGE? MASTER CRC-16 COMMAND, ADDRESS, DATA (1ST PASS); CRC-16 DATA (SUBSEQUENT PASSES)
MASTER RESET
MEMORY?
MASTER "1"s MASTER RESET? FIGURE FROM FIGURE
Figure Memory/Control Function Flowchart (continued)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
FROM FIGURE
START MISSION [WITH MASTER BITS [PASSWORD]
MISSION START DELAY PROCESS
STOP MISSION [WITH MASTER BITS [PASSWORD] START DELAY COUNTER MASTER DUMMY BYTE
MASTER DUMMY BYTE
DS1923 WAITS MINUTE
PASSWORD ACCEPTED?
DS1923 DECREMENTS START DELAY COUNTER
PASSWORD ACCEPTED?
MISSION PROGRESS?
SUTA DS1923 SETS WFTA
MISSION PROGRESS? DS1923 SETS WFTA
MEMCLR DS1923 SETS MEMCLR DS1923 WAITS SAMPLE PERIOD
MASTER RESET?
DS1923 INITIATES MISSION START DELAY PROCESS
DS1923 PERFORMS 8-BIT TEMPERATURE CONVERSION
MASTER RESET?
TEMPERATURE ALARM? DS1923 SETS WFTA LOGS FIRST SAMPLE
MISSION SAMPLES COUNTER DOES INCREMENT
DS1923 WAITS SAMPLE PERIOD SUTA THIS SECOND SAMPLE.
DS1923 COPIES DATA MISSION TIMESTAMP REGISTER
DS1923 STARTS LOGGING TAKING FIRST SAMPLE
PROCESS FIGURE
Figure Memory/Control Function Flowchart (continued)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Clear Memory with Password [96h]
Clear Memory with Password command used prepare device another mission. This command only executed mission progress. After command code, master must transmit 64-bit full-access password followed dummy byte. passwords enabled transmitted password different from stored full access password mission progress, Clear Memory with Password command fails. device stops communicating waits reset pulse. password correct passwords were enabled, device clears Mission Timestamp register, Mission Samples Counter register, alarm flags Alarm Status register. After these cells cleared, MEMCLR General Status register reads indicate successful execution Clear Memory with Password command. Clearing data-log memory necessary because Mission Samples Counter indicates many entries data-log memory valid.
Start Mission with Password [CCh]
DS1923 uses control function command start mission. mission only started previous mission been ended memory been cleared. After command code, master must transmit 64-bit full access password followed dummy byte. passwords enabled transmitted password different from stored fullaccess password mission progress, Start Mission with Password command fails. device stops communicating waits reset pulse. password correct passwords were enabled, device starts mission. SUTA sampling begins soon Mission Start Delay over. SUTA first sample written datalog memory time temperature alarm occurred. However, Mission Sample Counter does increment. sample period later, Mission Timestamp register regular sampling logging begins. While device waiting temperature alarm occur, WFTA flag General Status register reads During mission there only read access register pages.
Forced Conversion [55h]
Forced Conversion command used measure temperature humidity without starting mission. After command code, master must send byte conversion started. conversion result found 16-bit value Latest Temperature Conversion Result Latest Humidity Conversion Result registers. This command only executed mission progress (MIP cannot interrupted takes maximum 666ms complete. During this time memory access through 1-Wire interface blocked. device behaves same during mission when sampling interferes with memory/control function command. Memory Access Conflicts section details.
Stop Mission with Password [33h]
DS1923 uses control function command stop mission. Only mission that progress stopped. After command code, master must transmit 64-bit full access password followed dummy byte. passwords enabled transmitted password different from stored fullaccess password mission progress, Stop Mission with Password command fails. device stops communicating waits reset pulse. password correct passwords were enabled, device clears General Status register restores write access register pages. WFTA cleared. description general status register method clear WFTA bit.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Memory Access Conflicts
While mission progress while device waiting temperature alarm start mission, periodically temperature and/or humidity sample taken logged. This "internal activity" priority over 1-Wire communication. consequence, device-specific commands (excluding function commands 1-Wire reset) perform properly when internal "external" activities interfere with each other. affected commands Start Mission, Forced Conversion, Clear Memory, because they applicable while mission progress while device waiting temperature alarm. Table explains remaining five commands affected internal activity, detect this interference, work around interference more likely seen with highsample rate (one sample every second) with highresolution logging, which last 666ms when both temperature humidity recorded. With lower sample rates, interference hardly visible all. case, when writing driver software important know about possibility interference take measures work around
DS1923
Table Memory Access Conflicts Solutions
COMMAND INDICATION INTERFERENCE SOLUTION Wait 0.5s, 1-Wire reset, address device, repeat Write Scratchpad with same data, check validity CRC-16 command flow. Alternatively, Read Scratchpad verify data integrity. Wait 0.5s, 1-Wire reset, address device, repeat Read Scratchpad, check validity CRC-16 command flow. Wait 0.5s, 1-Wire reset, address device, issue Read Scratchpad, check byte. set, Copy Scratchpad successful. Wait 0.5s, 1-Wire reset, address device, repeat Read Memory with CRC, check validity CRC-16 memory page. Wait 0.5s, 1-Wire reset, address device, repeat Stop Mission. Perform 1-Wire reset, address device, read General Status register address 0215h, check bit. Stop Mission successful.
Write Scratchpad
CRC-16 command flow reads FFFFh.
Read Scratchpad
data read changes bytes bytes received FFh, including command flow. device behaves authorization code password valid copy function would end.
Copy Scratchpad
data read changes bytes bytes Read Memory with received FFh, including command flow, despite valid password.
Stop Mission
General Status register address 0215h reads while bits
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
1-Wire System
1-Wire system that single master more slaves. instances DS1923 slave device. master typically microcontroller. discussion this system broken down into three topics: hardware configuration, transaction sequence, 1-Wire signaling (signal types timing). 1-Wire protocol defines transactions terms state during specific time slots that initiated falling edge sync pulses from master. value pullup resistor primarily depends network size load conditions. DS1923 requires pullup resistor maximum 2.2k speed. idle state 1-Wire high. reason transaction needs suspended, must left idle state transaction resume. this does occur left more than (overdrive speed) more than 120s (standard speed), more devices reset. Note that DS1923 does quite meet full maximum time normal 1-Wire overdrive timing. With DS1923 must left longer than overdrive ensure that DS1923 1-Wire performs reset. DS1923 communicates properly when used conjunction with DS2480B DS2490 1-Wire driver adapters that based these driver chips.
Hardware Configuration
1-Wire only single line definition; important that each device able drive appropriate time. facilitate this, each device attached 1-Wire must have open-drain three-state outputs. 1-Wire port DS1923 open drain with internal circuit equivalent that shown Figure multidrop consists 1-Wire with multiple slaves attached. standard speed 1-Wire maximum data rate 16.3kbps. speed boosted 142kbps activating overdrive mode. DS1923 guaranteed fully compliant iButton standard. maximum data rate standard speed 15.4kbps 125kbps overdrive speed.
Transaction Sequence
protocol accessing DS1923 through 1-Wire port follows: Initialization Function Command Memory/Control Function Command Transaction/Data
VPUP MASTER RPUP DATA DS1923 1-Wire PORT
RECEIVE TRANSMIT OPEN-DRAIN PORT MOSFET
Figure Hardware Configuration
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Initialization
transactions 1-Wire begin with initialization sequence. initialization sequence consists reset pulse transmitted master followed presence pulse(s) transmitted slave(s). presence pulse lets master know that DS1923 ready operate. more details, 1-Wire Signaling section. numbers slave devices. each registration number, starting with least significant bit, master issues triplet time slots. first slot, each slave device participating search outputs true value registration number bit. second slot, each slave device participating search outputs complemented value registration number bit. third slot, master writes true value selected. slave devices that match written master stop participating search. both read bits zero, master knows that slave devices exist with both states bit. choosing which state write, master branches code tree. After complete pass, master knows registration number single device. Additional passes identify registration numbers remaining devices. Refer Application Note 187: 1-Wire Search Algorithm detailed discussion, including example.
DS1923
1-Wire Function Commands
Once master detected presence, issue eight function commands that DS1923 supports. function commands bits long. list these commands follows (see flowchart Figure 11).
Read [33h]
This command allows master read DS1923's 8-bit family code, unique 48-bit serial number, 8-bit CRC. This command only used there single slave bus. more than slave present bus, data collision occurs when slaves transmit same time (open drain produces wired-AND result). resultant family code 48-bit serial number results mismatch CRC.
Conditional Search [ECh]
Conditional Search command operates similarly Search command except that only those devices that fulfill certain conditions participate search. This function provides efficient means master identify devices multidrop system that have signal important event. After each pass conditional search that successfully determined 64-bit code specific device multidrop bus, that particular device individually accessed Match been issued, since other devices have dropped search process waiting reset pulse. DS1923 responds conditional search command five alarm flags Alarm Status register (address 0214h) reads humidity temperature alarm only occurs enabled (see Temperature Sensor Alarm Humidity Alarm sections). alarm always enabled. first alarm that occurs makes device respond Conditional Search command.
Match [55h]
Match command, followed 64-bit sequence, allows master address specific DS1923 multidrop bus. Only DS1923 that exactly matches 64-bit sequence responds following memory function command. other slaves wait reset pulse. This command used with single device multiple devices bus.
Search [F0h]
When system initially brought master might know number devices 1-Wire their registration numbers. taking advantage wired-AND property bus, master process elimination identify registration
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Skip [CCh]
This command save time single-drop system allowing master access memory functions without providing 64-bit code. example, more than slave present Read command issued following Skip command, data collision occurs multiple slaves transmit simultaneously (open-drain pulldowns produce wired-AND result). command sets DS1923 overdrive mode communication following this command must occur overdrive speed until reset pulse minimum 690s duration resets devices standard speed When issued multidrop bus, this command sets overdrive-supporting devices into overdrive mode. subsequently address specific overdrive-supporting device, reset pulse overdrive speed must issued followed Match Search command sequence. This speeds time search process. more than slave supporting overdrive present Overdrive-Skip command followed Read command, data collision occurs multiple slaves transmit simultaneously (open-drain pulldowns produce wiredAND result).
Resume [A5h]
DS1923 must accessed several times before mission starts. multidrop environment this means that 64-bit code after Match command must repeated every access. maximize data throughput multidrop environment, Resume command implemented. This command checks status and, set, directly transfers control memory/control functions, similar Skip command. only through successfully executing Match ROM, Search ROM, Overdrive-Match command. Once set, device repeatedly accessed through Resume command. Accessing another device clears bit, preventing more devices from simultaneously responding Resume command.
Overdrive-Match [69h]
Overdrive-Match command followed 64-bit sequence transmitted overdrive speed allows master address specific DS1923 multidrop simultaneously overdrive mode. Only DS1923 that exactly matches 64-bit sequence responds subsequent memory/control function command. Slaves already overdrive mode from previous Overdrive-Skip successful Overdrive-Match command remain overdrive mode. overdrive-capable slaves return standard speed next reset pulse minimum 690s duration. Overdrive-Match command used with single multiple devices bus.
Overdrive-Skip [3Ch]
single-drop this command save time allowing master access memory/control functions without providing 64-bit code. Unlike normal Skip command, Overdrive-Skip
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
MASTER RESET PULSE FROM MEMORY/CONTROL FUNCTION FLOWCHART (FIGURE FROM FIGURE
RESET PULSE?
MASTER FUNCTION COMMAND DS1923 PRESENCE PULSE
READ COMMAND?
MATCH COMMAND?
SEARCH COMMAND?
CONDITIONAL SEARCH COMMAND?
FIGURE
CONDITION MET?
DS1923 FAMILY CODE BYTE)
DS1923 MASTER DS1923 MASTER
DS1923 DS1923 MASTER
MATCH?
MATCH?
MATCH?
DS1923 SERIAL NUMBER BYTES)
DS1923
DS1923 DS1923 MASTER
MASTER
DS1923 MASTER
MATCH?
MATCH? DS1923
MATCH? DS1923 DS1923 MASTER
DS1923 BYTE
MASTER
DS1923 MASTER
MATCH?
MATCH?
MATCH?
FIGURE
FROM FIGURE MEMORY/CONTROL FUNCTION FLOWCHART (FIGURE
Figure 11a. Functions Flowchart
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
FIGURE
FROM FIGURE
SKIP COMMAND?
RESUME COMMAND?
OVERDRIVESKIP ROM?
OVERDRIVEMATCH ROM?
MASTER RESET?
MASTER
(SEE NOTE) MASTER RESET? MATCH?
MASTER
(SEE NOTE) MATCH?
MASTER
(SEE NOTE) MATCH?
FROM FIGURE
FIGURE
NOTE: FLAG REMAINS DEVICE ALREADY OVERDRIVE SPEED BEFORE OVERDRIVE-MATCH COMMAND ISSUED.
Figure 11b. Functions Flowchart (continued)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
1-Wire Signaling
DS1923 requires strict protocols ensure data integrity. protocol consists four types signaling line: reset sequence with reset pulse presence pulse, write-zero, write-one, read-data. Except presence pulse, master initiates these signals. DS1923 communicate different speeds: standard speed overdrive speed. explicitly into overdrive mode, DS1923 communicates standard speed. While overdrive mode fast timing applies waveforms. from idle active, voltage 1-Wire line needs fall from VPUP below threshold VTL. from active idle, voltage needs rise from VILMAX past threshold VTH. time takes voltage make this rise seen Figure duration depends pullup resistor (RPUP) used capacitance 1-Wire network attached. voltage VILMAX relevant DS1923 when determining logical level, triggering events. initialization sequence required begin communication with DS1923 shown Figure reset pulse followed presence pulse indicates DS1923 ready receive data, given correct memory function command. master uses slew-rate control falling edge, must pull down line tRSTL compensate edge. tRSTL duration 690s longer exits overdrive mode, returning device standard speed. DS1923 overdrive mode tRSTL longer than 80s, device remains overdrive mode. After master released line, goes into receive mode (Rx). 1-Wire pulled VPUP through pullup resistor case DS2480B driver, through active circuitry. When threshold crossed, DS1923 waits tPDH then transmits presence pulse pulling line tPDL. detect presence pulse, master must test logical state 1-Wire line tMSP. RSTH window must least PDHMAX PDLMAX RECMIN Immediately after tRSTH expired, DS1923 ready data communication. mixed population network, tRSTH should extended minimum 480s standard speed overdrive speed accommodate other 1-Wire devices.
DS1923
Read/Write Time Slots
Data communication with DS1923 takes place time slots that carry single each. Write time slots transport data from master slave. Read time slots transfer data from slave master. definitions write read time slots illustrated Figure communication begins with master pulling data line low. voltage 1-Wire line falls below threshold VTL, DS1923 starts internal timing generator that determines when data line sampled during write time slot long data valid during read time slot.
MASTER "RESET PULSE" VPUP VIHMASTER VILMAX tRSTL tMSP
MASTER "PRESENCE PULSE"
tPDH
tPDL tRSTH
tREC
RESISTOR
MASTER
DS1923
Figure Initialization Procedure: Reset Presence Pulse
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Master-to-Slave write-one time slot, voltage data line must have crossed threshold before write-one time tW1LMAX expired. write-zero time slot, voltage data line must stay below threshold until write-zero time tW0LMIN expired. voltage data line should exceed VILMAX during entire tW0L tW1L window. After threshold been crossed, DS1923 needs recovery time tREC before ready next time slot. Slave-to-Master read-data time slot begins like write-one time slot. voltage data line must remain below until read time expired. During window, when responding with DS1923 starts pulling data line low; internal timing generator determines when this pulldown ends voltage starts rising again. When responding with DS1923 does hold data line all, voltage starts rising soon over. (rise time) side internal timing generator DS1923 other side define master sampling window MSRMIN tMSRMAX) which master must perform read from data line. most reliable communication, should short permissible master should read close later than tMSRMAX. After reading from data line, master must wait until tSLOT expired. This guarantees sufficient recovery time tREC DS1923 ready next time slot.
sources also result signal glitching. glitch during rising edge time slot cause slave device lose synchronization with master and, consequence, result search command coming dead cause device-specific function command abort. better performance network applications, DS1923 uses 1-Wire front-end, which makes less sensitive noise also reduces magnitude noise injected slave device itself. DS1923's 1-Wire front-end differs from traditional slave devices four characteristics: falling edge presence pulse controlled slew rate. This provides better match line impedance than digitally switched transistor, converting high-frequency ringing known from traditional devices into smoother, low-bandwidth transition. slew-rate control specified parameter tFPD, which different values standard overdrive speed. There additional lowpass filtering circuit that detects falling edge beginning time slot. This reduces sensitivity high-frequency noise. This additional filtering does apply overdrive speed. There hysteresis low-to-high switching threshold VTH. negative glitch crosses does below VHY, recognized (Figure Case hysteresis effective 1-Wire speed. There time window specified rising edge hold-off time tREH during which glitches ignored, even they extend below threshold (Figure Case Deep voltage droops glitches that appear late after crossing threshold extend beyond tREH window cannot filtered taken beginning time slot (Figure Case tREH). Devices that have parameters tFPD, VHY, tREH specified their electrical characteristics improved 1-Wire front-end.
DS1923
Improved Network Behavior (Switchpoint Hysteresis)
1-Wire environment, line termination possible only during transients controlled master (1Wire driver). 1-Wire networks, therefore, susceptible noise various origins. Depending physical size topology network, reflections from points branch points cancel each other some extent. Such reflections visible glitches ringing 1-Wire communication line. Noise coupled onto 1-Wire line from external
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
WRITE-ONE TIME SLOT tW1L VPUP VIHMASTER VILMAX
tSLOT RESISTOR MASTER
WRITE-ZERO TIME SLOT tW0L VPUP VIHMASTER VILMAX tSLOT RESISTOR MASTER
tREC
READ-DATA TIME SLOT tMSR VPUP VIHMASTER VILMAX
MASTER SAMPLING WINDOW tSLOT RESISTOR MASTER DS1923
tREC
Figure Read/Write Timing Diagrams
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
tREH VPUP tREH
CASE CASE CASE
Figure Noise Suppression Scheme
POLYNOMIAL
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
STAGE
10TH STAGE
11TH STAGE
12TH STAGE
13TH STAGE
14TH STAGE
15TH STAGE
16TH STAGE INPUT DATA OUTPUT
Figure CRC-16 Hardware Description Polynomial
Generation
DS1923 uses types CRCs. 8-bit type stored most significant byte 64-bit ROM. master compute value from first bits 64-bit compare value stored within DS1923 determine data been received error-free. equivalent polynomial function this This 8-bit received true (noninverted) form, computed factory lasered into ROM. other 16-bit type, generated according standardized CRC-16 polynomial function This used error detection when reading register pages data-log memory using Read Memory with command fast verification data transfer when writing reading from scratchpad. contrast 8-bit
CRC, 16-bit always communicated inverted form. generator inside DS1923 (Figure calculates 16-bit shown command flowchart Figure master compares value read from device calculates from data decides whether continue with operation reread portion data with error. With initial pass through Read Memory with flowchart, 16bit value result shifting command byte into cleared generator, followed address bytes data bytes. password excluded from calculation. Subsequent passes through Read Memory with flowchart generate 16-bit that result clearing generator then shifting data bytes. With Write Scratchpad command, generated first clearing generator then shift-
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
command code, target addresses TA2, data bytes. DS1923 transmits this only data bytes written scratchpad include scratchpad ending offset 11111b. data start location within scratchpad. With Read Scratchpad command, generated first clearing generator then shifting command code, target addresses TA2, byte, scratchpad data starting target address. DS1923 transmits this only reading continues through scratchpad, regardless actual ending offset. more information generating values, refer Application Note
DS1923
Command-Specific 1-Wire Communication Protocol-Legend
SYMBOL Select TA-E/S <Data EOS> <Data EOP> <Data EOM> <PW/Dummy> Bytes> <Data> CRC-16 Loop Loop 1-Wire reset pulse generated master. 1-Wire presence pulse generated slave. Command data satisfy function protocol. Command "Write Scratchpad." Command "Read Scratchpad." Command "Copy Scratchpad with Password." Command "Read Memory with Password CRC." Command "Clear Memory with Password." Command "Forced Conversion." Command "Start Mission with Password." Command "Stop Mission with Password." Target Address TA1, TA2. Target Address TA1, with byte. Transfer many data bytes needed reach scratchpad offset 1Fh. Transfer many data bytes needed reach memory page. Transfer many bytes needed reach data-log memory. Transfer bytes that either represent valid password acceptable dummy data. Transfer bytes. Transfer undetermined amount data. Transmission byte. Transfer inverted CRC-16. Indefinite loop where master reads bytes. Indefinite loop where master reads bytes. DESCRIPTION
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Command-Specific 1-Wire Communication Protocol-Color Codes
Master-to-Slave Slave-to-Master
1-Wire Communication Examples
Write Scratchpad, Reaching Scratchpad (Cannot Fail)
Select <Data EOS> CRC-16 Loop
Read Scratchpad (Cannot Fail)
Select TA-E/S <Data EOS> CRC-16 Loop
Copy Scratchpad with Password (Success)
Select TA-E/S <PW/Dummy> Loop
Copy Scratchpad with Password (Fail TA-E/S Password)
Select TA-E/S <PW/Dummy> Loop
Read Memory with Password (Success)
Select <PW/Dummy> <Data EOP> CRC-16
Bytes>
CRC-16
Loop
Loop
Read Memory with Password (Fail Password Address)
Select <PW/Dummy> Loop
Clear Memory with Password
Select <PW/Dummy> Loop
verify success, read General Status register address 0215h. MEMCLR command executed successfully.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
1-Wire Communication Examples (continued)
Forced Conversion
Select Loop
DS1923
read result verify success, read addresses 020Ch 020Fh (results) Device Samples Counter address 0223h 0225h. count incremented, command executed successfully. Start Mission with Password
Select <PW/Dummy> Loop
verify success, read General Status register address 0215h. MEMCLR command executed successfully. Stop Mission with Password
Select <PW/Dummy> Loop
verify success, read General Status register address 0215h. command executed successfully.
Mission Example: Prepare Start Mission
Assumption: previous mission been ended using Stop Mission command. Passwords enabled. device DS1923. Starting mission requires three steps:
MASTER MODE
Step Clear data previous mission. Step Write setup data register page Step Start mission. Step Clear data previous mission. With only single device connected master, communication step looks like this:
COMMENTS Reset pulse Presence pulse Issue "Skip ROM" command Issue "Clear Memory" command Send dummy password Send dummy byte Reset pulse Presence pulse
DATA (LSB FIRST) (Reset) (Presence) bytes> (Reset) (Presence)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Step Write setup data register page During setup, device needs learn following information: Time Date Sample Rate Alarm Thresholds Alarm Controls (Response Conditional Search) General Mission Parameters (e.g., Channels Logging Format, Rollover, Start Mode) Mission Start Delay following data sets DS1923 mission that logs temperature humidity using 8-bit format both.
FUNCTION Time
ADDRESS 0200h 0201h 0202h 0203h 0204h 0205h 0206h 0207h 0208h 0209h 020Ah 020Bh 020Ch 020Dh 020Eh 020Fh 0210h 0211h 0212h 0213h 0214h 0215h 0216h 0217h 0218h
DATA minutes (Don't care)
EXAMPLE VALUES 15:30:00 hours
15th 2004
Date
Every minutes (EHSS 10°C 20°C High 40%RH 70%RH High
Sample rate Temperature Alarm Thresholds Humidity Alarm Threshold, software correction used
Clock through read-only registers
Enable high alarm Enable high alarm (enabled), EHSS (low sample rate) Normal start; rollover; 8-bit logging (Don't care)
Temperature Alarm Control Humidity Alarm Control Oscillator Control, sample rate selection General Mission Control Clock through read-only registers
Mission Start Delay
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
With only single device connected master, communication step looks like this:
MASTER MODE DATA (LSB FIRST) (Reset) (Presence) Data Bytes> Bytes> (Reset) (Presence) Data Bytes> (Reset) (Presence) Bytes> (Reset) (Presence) Reset pulse Presence pulse Issue "Skip ROM" command Issue "Write Scratchpad" command TA1, beginning offset TA2, address 0200h Write bytes data scratchpad Write through scratchpad Reset pulse Presence pulse Issue "Skip ROM" command Issue "Read Scratchpad" command Read TA1, beginning offset Read TA2, address 0200h Read E/S, ending offset 1Fh, flags Read scratchpad data verify Reset pulse Presence pulse Issue "Skip ROM" command Issue "Copy Scratchpad" command Send dummy password Reset pulse Presence pulse (AUTHORIZATION CODE) COMMENTS
DS1923
Step Start mission. With only single device connected master, communication step looks like this:
MASTER MODE
step successful, General Status register MEMCLR Mission Start Delay counts down.
COMMENTS Reset pulse Presence pulse Issue "Skip ROM" command Issue "Start Mission" command Send dummy password Send dummy byte Reset pulse Presence pulse
DATA (LSB FIRST) (Reset) (Presence) Bytes> (Reset) (Presence)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Software Correction Algorithm Temperature
accuracy high-resolution temperature conversion results (forced conversion well temperature logs) improved through correction algorithm. data needed this software correction stored calibration memory (memory page 18). consists reference temperature (Tr) conversion result (Tc) different temperatures, shown below. Temperature Conversion section binary number format. software correction algorithm requires additional values, which stored device. DS1923 these values 60°C Offset correction algorithm consists steps, preparation execution. preparation step first converts temperature data from binary decimal format. Next, three coefficients computed. execution step, temperature reading delivered DS1923 first converted from low/highbyte format (TcL, TcH) (Tc) then corrected Tcorr. Once step performed, three coefficients used repeatedly correct temperature reading temperature same device.
DESCRIPTION Cold reference temperature, high-byte. Cold reference temperature, low-byte. Conversion result cold reference temperature, high-byte. Conversion result cold reference temperature, low-byte. reference temperature, high-byte. reference temperature, low-byte. Conversion result reference temperature, high-byte. Conversion result reference temperature, low-byte.
ADDRESS 0240h 0241h 0242h 0243h 0244h 0245h 0246h 0247h
DESIGNATOR Tr2H Tr2L Tc2H Tc2L Tr3H Tr3L Tc3H Tc3L
Step Preparation Offset Tr2H/2 Tr2L/512 Offset Tr3H/2 Tr3L/512 Offset Tc2H/2 Tc2L/512 Offset Tc3H/2 Tc3L/512 Offset Err2 Err3 Err1 Err2 (Tr22 Tr12) (Err3 Err1)/[(Tr22 Tr12) (Tr3 Tr1) (Tr32 Tr12) (Tr1 Tr2)] (Tr1 Tr2)/(Tr22 Tr12) Err1 Tr12 Step Execution TcH/2 TcL/512 Offset Tcorr (convert from binary (convert from binary (convert from binary (convert from binary
(convert from binary (the actual correction)
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Numerical Temperature Correction Example
CONVERTED DATA FROM CALIBRATION MEMORY -10.1297°C 24.6483°C -10.0625°C 24.5°C RESULTING CORRECTION COEFFICIENTS -0.008741 0.000175/°C -0.039332°C Err2 0.0672°C Err3 -0.1483°C Err1 Err2 APPLICATION CORRECTION COEFFICIENTS SAMPLE READING 22.500000°C Tcorr 22.647275°C ERROR VALUES
DS1923
Note: software correction requires floating point arithmetic (24-bit better). Suitable math libraries microcontrollers found various websites included cross-compilers.
Software Correction Algorithm Humidity
accuracy humidity conversion results (forced conversion well logged data) improved through correction algorithm. data needed this software correction stored calibration memory (memory page 18). consists reference humidity (Hr) conversion result (Hc) three different humidity levels, shown below. data taken 25°C.
ADDRESS 0248h 0249h 024Ah 024Bh 024Ch 024Dh 024Eh 024Fh 0250h 0251h 0252h 0253h DESIGNATOR Hr1H Hr1L Hc1H Hc1L Hr2H Hr2L Hc2H Hc2L Hr3H Hr3L Hc3H Hc3L
correction algorithm consists steps: preparation execution. preparation step first converts humidity data from binary decimal format. Next, three coefficients computed. execution step humidity reading delivered DS1923 (raw data) first converted from low/highbyte format (HcL, HcH) (Hc) then corrected Hcorr. Once step performed, three coefficients used repeatedly correct humidity reading humidity same device.
DESCRIPTION reference humidity, high byte. reference humidity, byte. Conversion result reference humidity, high byte. Conversion result reference humidity, byte. Medium reference humidity, high byte. Medium reference humidity, byte. Conversion result medium reference humidity, high byte. Conversion result medium reference humidity, byte. High reference humidity, high byte. High reference humidity, byte. Conversion result high reference humidity, high byte. Conversion result high reference humidity, byte.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Step Preparation humidity data calibration memory, lower bits each byte This simplifies conversion from binary data format values one-line equation. ((Hr1H Hr1L) 5.02/65536 0.958)/0.0307 (convert from binary %RH) ((Hr2H Hr2L) 5.02/65536 0.958)/0.0307 ((Hr3H Hr3L) 5.02/65536 0.958)/0.0307 ((Hc1H Hc1L) 5.02/65536 0.958)/0.0307 ((Hc2H Hc2L) 5.02/65536 0.958)/0.0307 ((Hc3H Hc3L) 5.02/65536 0.958)/0.0307 Err1 Err2 Err3 [(Hr22 Hr12) (Err3 Err1) Hr32 (Err1 Err2) Hr12 (Err2 Err1)]/[(Hr22 Hr12) (Hr3 Hr1) (Hr32 Hr12) (Hr1 Hr2)] [Err2 Err1 (Hr1 Hr2)]/(Hr22 Hr12) Err1 Hr12 Step Execution ((HcH HcL) 5.02/65536 0.958)/0.0307 Hcorr (convert from binary %RH) (the actual correction)
DS1923
Numerical Humidity Correction Example
CONVERTED DATA FROM CALIBRATION MEMORY 20%RH 60%RH 90%RH 17.65%RH 56.41%RH 89.57%RH RESULTING CORRECTION COEFFICIENTS -0.186810 0.001948%RH 0.607143%RH ERROR VALUES
Err1 -2.35%RH Err2 -3.59%RH Err3 -0.43%RH
APPLICATION CORRECTION COEFFICIENTS SAMPLE READING 8.9%RH Hcorr 9.8%RH
Note: software correction requires floating point arithmetic (24-bit better). Suitable math libraries microcontrollers found various websites included cross-compilers.
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Temperature Compensation
data software correction humidity taken 25°C. Since temperature characteristics humidity sensor known, humidity readings taken other temperatures corrected, provided temperature time humidity conversion also known. Therefore, obtain most accurate humidity results, both temperature humidity should logged.
NAME FUNCTION Temperature time humidity conversion. Humidity sensor conversion constant. Linear compensation, enumerator. Quadratic compensation, enumerator. Linear compensation, denominator. Quadratic compensation, denominator. 0.0307 0.0035/°C 0.000043/°C2 >15°C: 0.00001/°C 15°C: -0.00005/°C 0.000002/°C2
Temperature compensation uses following equation: HTcorr (Hcorr 25°C) 25°C)2)/(K 25°C) 25°C)2) Hcorr humidity reading with software correction algorithm humidity already applied, explained previous section. function values other parameters explained table below.
DS1923
VALUE
Numerical Temperature Compensation Example
SAMPLE INPUT DATA 70°C Hcorr 24.445%RH APPLICATION CORRECTION COEFFICIENTS SAMPLE READING 0.00001/°C HTcorr (24.445 0.0307 0.0035 0.000043 452)/(0.0307 0.00001 0.000002 452) HTcorr 30.291%
Software Saturation Drift Compensation
Capacitive humidity sensors read higher humidity values than actual humidity level when they exposed high-humidity environment extended time period. DS1923's humidity sensor produces readings that higher than actual humidity when exposed humidity levels about 70%RH higher. This shift continues increase while device remains 70%RH above. This effect called saturation drift, hysteresis. This drift reversible. Readings return their regular level when DS1923 removed from high-humidity environment. possible compensate most error introduced saturation drift post-processing temperature humidity logs using equation below, which based laboratory tests curve-fitting techniques.
HScorr HTcorr
0156 3502
average software-corrected temperature-compensated humidity reading hour that device continuously exposed 70%RH higher. average software-corrected temperature reading hour that device continuously exposed 70%RH higher. number hours that device continuously exposed 70%RH higher. HTcorr humidity reading hour with software correction algorithm humidity temperature compensation already applied. Software Correction Algorithm Humidity Temperature Compensation sections details. numbers equation derived from curve fitting. They apply time scale hours.
ARHk
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory DS1923
Numerical Saturation Drift Compensation Example
SAMPLE INPUT DATA (HOUR) (°C) 25.1 25.0 24.9 25.0 25.1 25.1 25.0 24.9 HTcorr 93.70207%RH ARHk (%RH) 91.1 92.5 92.9 93.1 93.2 93.3 93.6 93.7 partial corrections: APPLICATION CORRECTION ALGORITHM PARTIAL CORRECTIONS (INDIVIDUAL ADDENDS) 1.024321 0.751140 0.544824 0.393535 0.283950 0.205086 0.148591 0.107428 3.458875
HScorr HTcorr partial corrections 93.70207%RH 3.458875%RH HScorr 90.24319%RH data this example taken from devices that were exposed several hours 90%RH 25°C
test chamber. drift hour decreases longer device exposed high humidity. correction algorithm compensates drift reasonably well. some applications, compensation necessary since error introduced saturation relatively small.
Configuration
5.89mm 0.51mm FRONT-SIDE BRANDING BACK-SIDE BRANDING
16.25mm
000000FBC52B
grochr
17.35mm
1-Wire® HygrochronWZ S1923
Package Information
latest package outline information land patterns, www.maxim-ic.com/packages. PACKAGE TYPE iButton PACKAGE CODE IB-6HB DOCUMENT 21-0266
Hygrochron Temperature/Humidity Logger iButton with Data-Log Memory
Revision History
REVISION NUMBER REVISION DATE 8/04 Initial release. Changed bullet from "Hydrophobic Filter Protects Sensor Against Dust, Dirt, Water, Contaminants" "Hydrophobic Filter Protects Sensor Against Dust, Dirt, Contaminants, Water Droplets/Condensation." Deleted "Application Pending" from bullet safety statement. 12/07 Added text Application section: Note that initial sealing level DS1923 achieves IP56. Aging conditions degrade integrity seal over time, applications with significant exposure liquids, sprays, other similar environments, recommended place Hygrochron under shield protect (See www.maxim-ic.com/AN4126). hydrophobic filter protect DS1923 from destruction event full submersion liquid. Created newer template-style data sheet. Deleted standard part number from Ordering Information table. DESCRIPTION PAGES CHANGED
DS1923
4/09 10/09
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600
2009 Maxim Integrated Products Maxim registered trademark Maxim Integrated Products, Inc.
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