CALLER EFFECTIVELY EFFICIENTLY IMPLEMENTED USING ON-CHIP RESOURCE
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OFF-HOOK CALLER USING Z893XX
CALLER EFFECTIVELY
EFFICIENTLY IMPLEMENTED USING ON-CHIP RESOURCES Z893XX 16-BIT FIXED-POINT
INTRODUCTION
This Application Note demonstrates implement Caller Identification (herein referred Caller CID) added feature telephone system using on-chip resources Z893XX. part Caller demonstration, this Application Note also describes multitasking system showing integrated microcontroller functions controller. Before presenting specific information building system, following rudimentary concepts first explained: (MDMF). SDMF typically displays date, time, telephone number calling party. MDMF typically displays date, time, telephone number name-as would appear telephone book listing-of calling party.
Note: Single Multiple Data Message Formats section that follows provides additional detail. References listed conclusion this Application Note.)
Caller Identification Delivery Variations-On- Off-Hook Solutions
Delivery Variations
primary methods delivery variations called on-hook off-hook. With on-hook delivery, information transmitted between first second rings incoming call. While relatively simple cost-effective analog solutions widely available on-hook operation. more appropriate solution off-hook operation. With off-hook delivery (also known Spontaneous Call Waiting with Caller Identification [SCWID] Caller Identification with Call Waiting [CICW], parties connected while third party attempting connect with these parties. Information only transmitted acknowledgment received from party interrupted. addition various call waiting signals that transmitted from Stored Program Control System (SPCS), special Customer Premise Equipment Alerting Signal (CAS) also transmitted. basic data transmitted using continuous phase binary Frequency Shift Keying (FSK). following sections further compare contrast off-hook operation.
What Caller Identification?
Caller Identification (CID) added feature telephone system that gives visual display calling party before connection. display typically custom Liquid Crystal Display (LCD) with two, three, four lines information. typical Message output display appear follows:
08:16AM 8/18 Call#1 123-456-789 John
Before even picking phone, feature easily identifies caller, caller's telephone number, time call. name number caller recognized response desirable), then person receiving call phone ring merrily away, perhaps allow answering machine pick call. Both primary messaging formats supported: Single Data Message Format (SDMF) Multiple Data Message For-
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INTRODUCTION (Continued) On-Hook Delivery
On-hook delivery form adjunct add-on unit commercially available solution this time. This simple type system requires limited circuitry perform detection ringing current then demodulate signal display resulting data. Figure shows delivery this data sandwiched between first second rings. larger amplitude, lower frequency, waveforms beginning Captured Time Buffer (CAP_TIM_BUF) ringing pulses. Filtered Time (FILT_TIME1) shows these ringing pulses greater detail (see Figure smaller amplitude, higher frequency, waveform data.
Figure On-Hook Delivery Between First Second Rings
better understand function, somewhat idealized simulation data shown Figure data being transmitted here first then then another finally Power Spectral Density plot shows frequency content this signal those prefer view such signals frequency domain.
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Application Note Off-Hook Caller Using Z893XX
Figure Idealized Data Power Spectral Density
course, data real world clean idealized situation shown Figure quick look real data (refer Figure shows actual received data. easy that amplitude high-frequency segment that low-frequency segment quite different.
addition, there noise superimposed signal most noticeably peaks troughs. (Refer Demodulation section more detailed discussion.)
Figure Real Data
Single Multiple Data Message Formats
Within data itself, there structure Single Data Message Format (SDMF) Multiple Data Message ForAN002300-DSP0799
(MDMF). While SDMF allows only date, time, phone number caller transmitted, MDMF allows caller's name transmitted also. MDMF, fact,
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lows transfer almost type data that represented ASCII. Figure shows overview MDMF. channel seizure series alternating which only supplied on-hook case. off-hook case, data transmission starts with mark signal, which series 1's. parameter words limited message. There
many parameter messages each parameter message consists parameter type, parameter length, parameter word. Optional mark signals transmitted between frames. checksum every transmission.
Note: parameter data variable length.
Channel Seizure
Mark Signal
Message Message Parameter Parameter Parameter Checksum Length Words Type Length Type 303623330383136 34303833373038353034 44617665205279616E
10101010 11111111 10000000
Figure Overview Messaging Structure
On-Hook Decoder Block Diagram
simple block diagram shown Figure further explains on-hook solution. band-pass filter
cluded filter out-of-band signals. demodulator converts analog signal into binary data. SDMF/MDMF section removes start stop bits determines messaging format. data then either stored static displayed LCD.
Band Pass Filter
Demodulator
SDMF/MDMF Data Recovery
Driver Supervisory SRAM/IF
Figure On-Hook Functional Software Modules
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Application Note Off-Hook Caller Using Z893XX
Display
display usually small Liquid Crystal Display (LCD) capable displaying date, time, telephone number, caller's name. person being called simply waits until second ring, allowing time data received. Usually there some memory these units messages stored later retrieval. amount memory varies, usually between messages stored. These systems normally, always, battery-powered actual time system operation generally limited time between first second rings. Once call been answered, system power-down standby mode.
tone presence VOX. separate issues exist: inadvertent detection similarity with speech (the called Talk-Off problem) failure detect (the called Talk Down problem). This type system been widely implemented using analog solutions primarily because difficulties involved implementing costeffective, manufacturable, robust solution using analog technology. contrast, using digital filters, manufacturing difficulties associated with using critically matched components (resistors, capacitors, inductors, like) largely obviated. addition, digital solution made adaptive, which major bonus. Further, implementations that variants other areas world simply matter software upgrades. course, there some trade-offs. Analog-to-digital (AD) conversion must supported with ancillary requirements. course, digital-to-analog (D-A) conversion must also supported; however, balance solution superior analog solution.
What Advantages DSP?
on-hook operation, simple cost-effective analog solutions exist; therefore, required. offhook operation, more sensible choice. difficulty arises accurate detection special
BUILDING CALLER IDENTIFICATION SYSTEM
build your Caller Identification (CID) system using information provided this Application Note. There many ways this, perhaps simplest solution purchase ready-made evaluation board complete with firmware. also write software build hardware described here. While building hardware reasonably straightforward (see Figures software development more complex. would need purchase firmware development tools such emulator, assembler, linker, debugger. This Application Note assumes that reader content adopt firmware provided ready-made evaluation board. Detailed descriptions hardware firmware follow.
Hardware On-Hook Operation
Figure illustrates Z893XX Connection Block Diagram; Figure illustrates Caller Demo Board Schematic Diagram.
Ring Z893XX Logic
RJ11 RJ11
Phone
CODEC
Display Keys
Figure Z893XX Connect Block Diagram
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AGND
.1µF AGND 16V_TANT HO_CNT CODEC 5.1K AGND Ring_Det 2N4401 AGND 206K 155K 4.7K 4.7K VCCA 4.7K AGND AGND AGND 5.1K
AGND +C19
HYBRID
AGND
CODEC
AGND
1N4001
1N4001
PHONE LINE RINGER/CALLER
.01µF 250V
ELECT .022µF 100K 119K VCCA
150K
MNBD914 MNBD914
MNBD914 MNBD914
Figure Caller Demo Board Schematic-Part
HC4066 0.47µF .009µF VCCA .01µF
MICROTRAN TH2104 MIDCOM 671-8240)
AGND
390pF
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CID_CNT 4.7K 180K .01µF 250V 206K AGND
AGND
AGND
100K HI_CNT AGND VCCA HAMLIN HR3621A0500 .1µF 4.7K .1µF 100K AGND .1µF 100K CODEC .01µF .01µF
SCLK
1/4W
AGND
MMBD914
R_CNT
2N4401
RING
RJ11 .1µF
Application Note Off-Hook Caller Using Z893XX
TOUT
VFXI+ VFXIGSX /TSX DOUT BCLK MCLK
RJ11
RING
KT8554
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Application Note Off-Hook Caller Using Z893XX
Figure Caller Demo Board Schematic-Part
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SADR0 SADR1 SADR2 SADR3 SADR4 SADR5 SADR6 SADR7 SADR8 SADR9 SADR10 SADR11 SADR12 SADR13 SADR14
EXT0 EXT1 EXT2 EXT3 EXT4 EXT5 EXT6 EXT7
44-PIN PLCC
Application Note Off-Hook Caller Using Z893XX
RING_DET C3_4 CID_CNT
WR3/
CY7C198
.1µF .1µF CU11 .1µF
Figure Caller Demo Board Schematic-Part
.1µF
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R_CNT HO_CNT RESET HI_CNT DRIVE EXT12 EXT13 EXT14 WR3/ C1_2 C3_4 LED0 LED1 EXT11 EXT10
EXT0 EXT1 EXT2 EXT12 EXT13 EXT14 EXT15 EXT3 EXT4 EXT5 EXT6
RESET RDYE ER/W SCLK INT1 INT2 EXT11 EXT10 EXT9 EXT8 EXT7 RESET ER/W SCLK INT1 INT2 EXT11 EXT10 EXT9 EXT8 EXT7
HALT INT0 EXT0 EXT1 EXT2 EXT12 EXT13 EXT14 EXT15 EXT3 EXT4 EXT5 EXT6
PIN003 DADR8 DADR7 DADR6 DADR5 DADR4 DADR3 DADR2 DADR1 DADR0 ER/W DADR9 RESET DRIVE EXT12 EXT13 EXT14 PIN002 PIN004 LED0 LED1 EXT11 EXT10
C1_2 SADR10 EXT9 SADR9 SADR11 SADR13 SADR14 SADR12 SADR8 SADR0 EXT4 EXT7 EXT8 EXT0 EXT2 SADR7 EXT15 EXT1 EXT5 EXT6 LED5 LED6 SADR5 ER/W SADR1 SADR2 SADR4 SADR3 LED3 EXT3 LED4 LED2
SADR0 SADR1 SADR2 SADR3 SADR4 SADR5 SADR6 SADR7 SADR8 SADR9 SADR10 SADR11 SADR12 SADR13 SADR14 WR3/
C1_2 SADR10 EXT9 SADR9 SADR11 SADR13 SADR14 SADR12 SADR8 SADR0 EXT4 EXT7 EXT8 EXT0 EXT2 SADR7 EXT15 EXT1 EXT5 EXT6 LED5 LED6 SADR5 ER/W SADR1 SADR2 SADR4 SADR3 LED3 EXT3 LED4 LED2
EXT8 EXT9 EXT10 EXT11 EXT12 EXT13 EXT14 EXT15
.1µF
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Application Note Off-Hook Caller Using Z893XX
Blocks
Phone Line Interface. Includes transformer addi-
Connect jack telephone. Apply power. Press RESET button. displays READY. Connect scope order check levels. amplitude signal approximately peak-to-peak, when data received between first second rings. adjusted necessary. displays results. message SDMF format, then display shows date, time, telephone number calling party. message MDMF format, display shows date, time, telephone number, name.
tional components used isolate circuits from line. Protection needed since ring high- voltage signal damage circuits on-/off- hook relay.
Ring Detect Circuit. Gives digital input (RING_DET sig-
nal) indicating presence rings phone line.
Caller Gain Control. Controlling gain signals coming from phone line interface codec analog input. enables this path CID_CNT control signal. Codec. analog front end. codec data format 8-bit µ_law. controls sampling rate signal serial shifts SCLK signal. receives serial data from transmits serial data TXD. Hybrid. sends acknowledge
Off-Hook Data
Figure illustrates actual delivery data when operating off-hook mode. simple on-hook mode, data delivered between first second rings.) Off-Hook mode, data arrive time call waiting occur. larger amplitude, lower frequency waveforms beginning Captured Time Buffer (CAP_TIM_BUF) call waiting tone. data seen after gap. during this that acknowledgment (ACK) generated DSP. This shown connected receive side. Filtered Time (FILT_TIME1) shows call waiting tone greater detail.
Hybrid back phone line interface. enables this path using HO_CNT control signal.
On-Hook Operation
operation relatively simple operation should possible area where available subscribed Connect jack telephone line simulator, available.
Figure Off-Hook Delivery
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BUILDING CALLER IDENTIFICATION SYSTEM (Continued) Off-Hook Decoder Block Diagram
When on-hook solution compared off-hook solution, number differences apparent. addition modules used on-hook, there filter both high- low-band portions signal. There also special detector timing (see Detection section, which follows). Once this special tone detected, then acknowledgment must sent back DTMF generator module also included. addition, whether system on-hook off-hook must determined.
Band-Pass Filter
Demodulator
SDMF/MDMF Data Recovery
High Filter Detector Timing Filter Supervisory On/Off Hook SRAM/IF Timer Driver
Figure Off-Hook Functional Software Modules
Off-Hook Operation
operation Off-Hook mode simple OnHook extra communication involved. Again, operation should possible area where Caller with Call Waiting (CIDCW) available subscribed Connect jack line CIDCW simulator available.
Note: simulator preferable mandatory additional development planned because minimum three lines involved.
Connect scope check levels. amplitude signal should approximately peak-to-peak, when data being transmitted. Adjust R31, necessary. then displays results. listen line should hear call waiting tone followed special tone. tone should detected module should sent followed immediately data transmission from SPCS simulator. message SDMF format, then display should show date, time, telephone number calling party. message MDMF format, display should show date, time, telephone number, name.
Line calls line initially. Line interrupts line
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Demodulation
continuous phase binary Frequency Shift Keying (FSK) demodulation function integrated into DSP. frequencies 1200 2200 After protocol handshaking requirements completed, basic data transmitted using FSK. There phase discontinuities there only frequencies involved signal. lower frequency (1200 represents mark (logic higher frequency (2200 represents space (logic example, continuous stream 0-1-0-1 sent, then full cycle 1200 sent (833 then approximately half cycles 2200 sent (833 µs). Again, full cycle 1200 sent (833 then approximately half cycles 2200 sent (833 µs). There parity error checking beyond checking checksum, which sent transmission. There however, start stop added each 8-bit transmitted word. transmission rate 1200 baud (bits sec.). demodulation very similar that employed standard baud rate V.21/Bell103 modem. (Refer Reference conclusion this Application Note.)
this MDMF format. data sent format Parameter words, where parameter type length transmitted simple binary calling name number information transmitted using regular ASCII. last word Single Multiple Data Message frames checksum. checksum two's complement modulo binary representation other words message including message type length well parameter type length. When making this calculation, remove start stop bit. course, binary sum, sum, decimal sums equivalent. obtain two's complement simple approach would with %FF. Using data example Table then using hexadecimal calculations checksum
(MOD(sum(80,27,01,08, 20,52,79,61,6E), 100), (MOD(7A8, 100), (A8, =%57
Data Recovery
data format best understood examination example Table which follows. this typical example, overall message type 128, which means that
course, practical application, actual calculation actually much less cumbersome natural modulo nature byte. Since there error correction, practical application checksum simply compare received checksum with calculated checksum. they agree, then data some should, general, displayed.
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BUILDING CALLER IDENTIFICATION SYSTEM (Continued)
Table Typical Multiple Message Data Format (MSB-LSB) Message Type Message Length Parameter Type Parameter Length Month Hour Minute Parameter Type Parameter Length 4083708504 ASCII/HEX% 0/30 6/36 2/32 3/33 0/30 8/38 1/31 6/36 4/34 0/30 8/38 3/33 7/37 0/30 8/38 5/35 0/30 4/34 D/44 a/61 v/76 e/65 Space/20 R/52 y/79 a/61 n/6E Stop Start
Parameter Type Parameter Length John
Checksum
Detection
Consumer Premise Equipment Alerting Signal (CAS) detection function integrated into DSP. basic premise detector periodic nature tones contrasted aperiodic nature voiced VOX. frequencies 2130 2750 which means that itself Dual Tone Multi Frequency (DTMF) signal. However, frequencies quite distinctly beyond range normal signaling DTMF frequencies. signal first filtered using
high-filter 2750 also low-filter 2130 resultant outputs then rectified tested minimum amplitude requirements. minimum amplitude requirements both frequencies, then timer started check possible duration. amplitude must constantly exceed minimum requirements period exceed predetermined gating limit order determine detection. detector Interrupt Service Routine (ISR) services detection shown source code listing. (This
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Application Note Off-Hook Caller Using Z893XX
portion listing that begins with casint: ends with ret;return from Codec ISR. Refer Source Code section conclusion this Application Note.) This portion code first saves accumulator status register. Then data retrieved from codec. codec register ext6 double-buffered, which simply means that there really ext6 registers: ext6-0 ext6-1. assembler only reads ext6, which apparently there redundant load ext6 push data out. Next filters called. Since basic biquad structure used, then filters called three times give sixth-order filter. This whole process repeated twice: once high filter 2750 once filter 2130 band. final portion casint restores accumulator status register. basic biquad structure performs core filtering shown source code listing. (This portion listing that begins with biquad: ends with ;return from biquads.) code been structured that updates actual filter calculations performed within subroutine biquad. first section this code updates input taps delays time. newest sample data X(n) data time replaces older X(n), which turn saved X(n-1) current sample delayed that (n-1). This process repeated taps. perform filter computations (coeff sample) auto increment used single-cycle MPYA (MultiPlY Accumulate) instruction used. fundamental equations
Y(n) b0*X(n)
logically organized with lines characters each that overrun; however, physical manifestation lines. ASCII character displayed along with many other characters. commonly case with these devices, low-level drivers controller actually mounted module. that needed relatively simple high-level software driver instruct which character display where place bangs over ASCII data controller using external data DSP. relatively slow device, slower than normal operations, updating presents minimal overhead DSP. Communication done using specialized series instructions. Once initialized, data simply transmitted.
Call Progress. Call progress essentially sequential this system. ring must detected first before anything happen. Once call established, only events happen: either call interrupt occurs does occur. Data comes only flavors: SDMF MDMF. After data received, then obviously should displayed. simple state machine takes care logical progress call. This adoption microcontroller function within engine. call, disconnection occurs entire cycle repeats. Memory Storage. Because multitasking features capability common processors, normal call progress-especially on-hook/off-hook monitoring, system supervision, memory calls received, display tasks-can handled single processor. sake simplicity, memory storage been added this demonstration. external addressing capability will allow this feature easily added.
where:
filter coefficients X(n) current sample previous sample X(n-2) second previous sample Y(n) current output previous output Y(n-2) second previous output
Available Caller Identification?
There real technical limitation national implementation Caller Identification. Other issues such right privacy obviously beyond scope this article. Currently service available most, all, U.S. states.
Conclusion
This Application Note described only most elementary features Caller Identification system. Many other value-added features added, such ring only certain callers. this example, ringer might suppressed only activated after caller identity recognized. This type feature other features could easily added part controller functions. Future feature expansion limited only user's imagination.
last section this code updates output taps delays time. newest output Y(n) output data time replaces older Y(n), which turn saved Y(n-1) current output delayed that (n-1). Y(n-1) itself saved y(n-2). process repeated output taps.
Display Drivers. display used here standard off-
the-shelf matrix with 16-character 4-line display.
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BUILDING CALLER IDENTIFICATION SYSTEM (Continued) References
Bellcore, Technical Reference TR-NWT-000031 Bellcore, Technical Reference TR-NWT-001188 Bellcore, Generic Requirements GR-30-CORE Bellcore, Special Report SR-TSV-002578 Bellcore, Special Report SR-TSV-002476 Gibson, Principles Digital Analog Communications
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SOURCE CODE
casint: SAVE Contents return ;-pusha ;save push a,sr ;load with ;save
Sixth-order triple biquad filter ;-lda,#X11;load with address (X11) input samples ldp0:0,a;point input sample lda,#BF1;address (BF1) filter coefficients ldp0:1,a;point filter coefficients ;read input sample x(n)
ldext6,a;push µ-law input sample ext6-2 ext6-1 lda,ext6;load µ-law data accumulator x(n) µ-law;µ-law result 14-bit sign magnitude number slla;shift left logical/multiply slla;shift left logical/multiply ldx,a;x data ldtempist,a;store temporary input storage call biquad;perform standard biquad call biquad;perform standard biquad call biquad;perform standard biquad save output filter response y(n) ldoutgbf1,a;store third-stage output ldext6,a;CODEC1 output y(n) auto hardware µ-law Sixth-order triple biquad filter ;-lda,#X41;load with address (X41) input samples ldp0:0,a;point input sample lda,#BF2;address (BF2) filter coefficients ldp0:1,a;point filter coefficients ;read input sample x(n) x,a;x data
lda,tempist;restore temporary input storage
call biquad;perform standard biquad call biquad;perform standard biquad AN002300-DSP0799 PRELIMINARY
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SOURCE CODE (Continued)
call biquad;perform standard biquad save output filter response y(n) ldoutgbf2,a ;store third-stage output adda,outgbf1 ;debug test ldext6,a;CODEC1 output y(n) auto hardware µ-law endinti: RESTORE Contents return ;-popa ;restore ldsr,a popa ;load with ;restore value SIEF;Enable interrupts ret;Return from CODEC biquad: ;-;perform filter computations (coeff sample) using auto increment b0*X(n) B1*X(n-1) b2*X(n-2) +a1*Y(n-1) a2*Y(n-2) ;Input Sample ;Output ;P0:0 Points Input/Output Samples ;P0:1 Points Coefficients X(n) X(n-1) X(n-2) Y(n-1) Y(n-2)
update input sample buffer ldy,@p0:0;y saves ldx,@p0:0;x saves (n-1) ld@p0:0+,y ;(n-1) ldy,@p0:0;y saves (n-2) ld@p0:0,x ;(n-2) (n-1) lda,p0:0;p0:0 points (n-2) suba,#%2;decrement ldp0:0,a;p0:0 points b0*X(n) B1*X(n-1) b2*X(n-2) +a1*Y(n-1) a2*Y(n-2) mpya mpya mpya @p0:1+,@p0:0+,on;A= X11) X(n) @p0:1+,@p0:0+,on;b1 @p0:1+,@p0:0+,on;b2 @p0:1+,@p0:0+,on;a1 X(n-1) X(n-2) Y(n-1) AN002300-DSP0799 p0:0 points (n-2) p0:0 points p0:0 points (n-1) ld@p0:0+,x ;(n) sample p0:0 points
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Application Note Off-Hook Caller Using Z893XX Y(n-2)
adda,p;add result last multiply slla;scale back divide coefficients ldx,a;return result ;update output buffer lda,p0:0;p0:0 points Y12+1 suba,#%2;decrement ldp0:0,a;p0:0 points (n-1) ldy,@p0:0;y saves (n-1) ld@p0:0+,x ;Y11 result ld@p0:0+,y ;Y12 Y(N-2) output filter response y(n) a,x;store stage output ret;Return from biquads
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