AN2158 Freescale Semiconductor, Inc. Designing with MC68HC90

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

AN2158 Freescale Semiconductor, Inc. Designing with MC68HC90

Datasheet Thumbnail

Top Searches for this datasheet

Order this document AN2158/D
AN2158
Freescale Semiconductor, Inc.
Designing with MC68HC908JL/JK Microcontroller Family
Yan-Tai Applications Engineering Microcontroller Division Hong Kong
This application note describes design techniques Motorola MC68HC908JL/JK family devices, hereafter referred JL/JK family, JL/JK single device. full device specifications, please refer data sheets, Motorola order numbers: MC68HC908JL3/H MC68HC08JL3/H.
Introduction
JL/JK family popular, low-cost, general purpose MCUs Motorola HC08 Family. JL/JK devices have 4096 1536 bytes memory user code, bytes RAM, crystal oscillator, analogto-digital converter, 16-bit timer, available various packages. generation FLASH memory FLASH parts program-erase cycle 10,000 times. versatility JL/JK makes device suitable many applications, sometimes finding itself some very noisy environments. These noise interference problems made worse poor circuit design layout, resulting intermittent failures even complete breakdown.
Motorola, Inc., 2001
More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note
avoid these undesirable effects, there some basic techniques that applied during circuit design layout. This application note outlines some recommendations. JL/JK family comprises array devices with common modules, different size FLASH, ROM, oscillator options. Table below lists devices JL/JK family: Table MC68HC908JL/JK Family
Freescale Semiconductor, Inc.
Device MC68HC908JL3 MC68HRC908JL3 MC68HLC908JL3 MC68HC908JK3 MC68HRC908JK3 MC68HLC908JK3 MC68HC908JK1 MC68HRC908JK1 MC68HLC908JK1 MC68HC08JL3 MC68HRC08JL3 MC68HC08JK3 MC68HRC08JK3 MC68HC08JK1 MC68HRC08JK1
FLASH (Bytes) 4096 4096 4096 4096 4096 4096 1536 1536 1536
(Bytes) 4096 4096 4096 4096 1536 1536
Oscillator XTAL XTAL XTAL XTAL XTAL XTAL XTAL XTAL XTAL
Count pins pins 28-pins pins pins pins pins pins pins pins pins pins pins pins pins
Comments
Operating voltage: 2.4V
Operating voltage: 2.4V
Operating voltage: 2.4V
NOTE: These devices available various packages; please refer device data sheets full ordering part numbers.
AN2158 More Information This Product, www.freescale.com MOTOROLA
Application Note Power-Up Power-Down Requirements
Power-Up Power-Down Requirements
precautions described below must followed power-up power-down, otherwise unpredictable behavior occur.
Power-on reset (POR) circuit re-arms 100mV
Power supply rise-time
Freescale Semiconductor, Inc.
Power supply fall-time
100ms
500ms
100ms
Note: Related parameters specified datasheet.
Figure Power Supply Power-Up/Down Requirements Meeting power-on reset requirements power-up, supply voltage rise-time should short possible; less than 143ms operation; best less than 100ms. power-down, supply voltage should fall below less than 500ms. Before power-up again, supply voltage must fall below 100mV JL/JK power-on reset circuit rearm. addition, keep external reset (RST) pulled least until supply voltage reached operating level. Improper power-up power-down conditions cause problems MCUs, just JL/JK. Since contains microprocessor running program, improper power-up cause behave erratically execute runaway codes. severe cases, devices with electrically erasable memory (e.g. FLASH memory) could experience memory erasure these power-up power-down parameters taken seriously.
AN2158 MOTOROLA More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note Clock Generation Distribution
reliable, stable clean reference clock input very important application designs, since clock heart MCU. oscillator options available JL/JK family: crystal oscillator oscillator. oscillator option defined mask layer silicon distinguished device part numbering. crystal oscillator option also supports ceramic resonators direct clock input.
Freescale Semiconductor, Inc.
Clock distribution
Figure shows reference clock divided distributed main modules inside JL/JK.
OSC1
OSC2
HC(9)08JL/JK XTAL CIRCUIT
HRC(9)08JL/JK CIRCUIT
XTALCLK
RCCLK
2OSCOUT
MODULE
OSCOUT
INTERNAL CLOCKS
CLOCK
TIMER MODULE MODULE
CLOCK
Figure JL/JK Clock Distribution
AN2158 More Information This Product, www.freescale.com MOTOROLA
Application Note Clock Generation Distribution
Crystal connection between OSC1 OSC2 pins High-frequency crystal
With crystal oscillator option, external component values vary slightly high frequency frequency crystals.
following components when using high frequency crystal (1MHz 24MHz).
OSC1
OSC2
Freescale Semiconductor, Inc.
100k 300k Crystal (optional)
1MHz 24MHz 20pF 20pF
Figure Components 1MHz 24MHz Crystal Oscillator Low-frequency crystal following components when using 32.768kHz crystal.
OSC1
OSC2
100k Crystal
32.768 15pF 20pF 50pF
Figure Components 32kHz Crystal Oscillator
AN2158 MOTOROLA More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note
Crystal oscillator start-up time Figure shows typical crystal start-up waveform JL/JK devices. Notice that crystal oscillation only becomes stable when supply voltage rises above circuit trip point.
+2.2V
Freescale Semiconductor, Inc.
Output
Figure Crystal Oscillator Start-Up
External clock drive into OSC1
alternative input crystal oscillator option square wave from external oscillator, driven directly into OSC1 pin, leaving OSC2 unconnected. square wave should have duty cycle. Using this method, maximum clock input 32MHz, providing frequency 8MHz. Figure shows external clock drive.
OSC1
OSC2
connection
Figure External Oscillator Drive OSC1
AN2158 More Information This Product, www.freescale.com MOTOROLA
Application Note Clock Generation Distribution
Resistor-Capacitor connection OSC1
Figure shows basic connections option. Refer data sheet values versus desired frequency.
Basic connection
OSC1
OSC2
Freescale Semiconductor, Inc.
OSC2 RCCLK output PTA6
Figure Oscillator Connection improve noise immunity reduce switching transients, component configuration shown Figure recommended.
Better connection
This configuration will reduce emission power least 15dB.
OSC1
OSC2
0.01µF reduce emission power supply rail Resistor smooth discharge 0.01µF
Figure Improved Oscillator Connection Calculating frequency Although values frequency obtained from graph data sheet, possible calculate this frequency. Figure shows typical capacitor charge/discharge curve. calculation includes overshoot time parasitic capacitance.
AN2158 MOTOROLA More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note
0.5VDD Virtually linear Waveform OSC1 approx.
Sharp discharge
Freescale Semiconductor, Inc.
Capacitor charge time:
period including overshoots:
OSC1
frequency:
frequency, including parasitic capacitance:
Parasitic capacitance approx.
Figure Frequency Calculation
FLASH Memory Block Protection
FLASH block protect register ($FE09)
JL/JK FLASH devices, FLASH memory block protected after reset. FLASH program erase operation only possible when FLASH memory unprotected writing FLASH block protect register $FE09 (write into $FE09 unprotect entire array).
AN2158
More Information This Product, www.freescale.com
MOTOROLA
Application Note Replacing FLASH devices with devices
Replacing FLASH devices with devices
following sub-sections outline precautions when switching from FLASH with devices.
USER code
Freescale Semiconductor, Inc.
user code FLASH device used directly device long code does access FLASH related registers (i.e. $FE08 $FE09). These registers reserved locations device.
FLASH related registers
FLASH related registers ($FE08 $FE09) reserved locations device.
Monitor
monitor program device used testing only. FLASH programming operations available.
Using clock option
frequency characteristics identical FLASH devices. Please refer respective data sheets frequency curves.
Low-Voltage MC68HLC908JL/JK
JL/JK family includes three low-voltage devices, with operating voltage 2.4V: MC68HLC908JL3 MC68HLC908JK3 MC68HLC908JK1
differences devices are: FLASH memory only read. Program erase achieved operating voltage
AN2158 MOTOROLA More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note
There low-voltage inhibit circuit. Therefore, low-voltage reset. associated register bits reserved bits. Only crystal oscillator direct clock input supported.
Layout Critical Signals
layout often overlooked majority cost-sensitive circuit designs. surprising that signal routed affect overall performance circuit PCB. following sub-sections outline some techniques. Crystal oscillator connections Connect these critical components close possible with shortest return path ground pin. Each should decoupled ground with capacitor. Figure shows examples layout crystal oscillator components.
Jumper wire 20-pin PDIP JK1/JK3
Freescale Semiconductor, Inc.
Jumper wire
28-pin PDIP
0.01µF 0.1µF decoupling capacitors *Short series resistor required.
0.01µF 0.1µF decoupling capacitors
Figure Crystal Oscillator Layout
AN2158 More Information This Product, www.freescale.com MOTOROLA
Application Note Layout Critical Signals
Ground return high-current devices
Keep high current return ground paths separate from current return ground paths, join them single point near regulator power supply input.
7805
current path
28-pin SDIP
Freescale Semiconductor, Inc.
point here
High current path
Driver
Figure Ground Return High Current Devices Long signal paths pins Terminate long trace carrying analog signal with decoupling capacitor input (see Figure Figure 13).
Terminate each long input trace with decoupling capacitor close possible.
PTB0/ADC0 PTB1/ADC1
0.01µF
0.01µF
Long trace
Figure Long Analog Signal Paths
AN2158 MOTOROLA More Information This Product, www.freescale.com
Freescale Semiconductor, Inc. Application Note
Previous Layout
Freescale Semiconductor, Inc.
Improved Layout
Decoupling capacitors long signal traces
Large power ground planes Traces longer than 10cm
Ground plane
ground VDD/VSS decoupling (0.01µF, 0.1µF)
Figure Example Layout
Motorola reserves right make changes without further notice products herein. Motorola makes warranty, representation guarantee regarding suitability products particular purpose, does Motorola assume liability arising application product circuit, specifically disclaims liability, including without limitation consequential incidental damages. "Typical" parameters which provided Motorola data sheets and/or specifications vary different applications actual performance vary over time. operating parameters, including "Typicals" must validated each customer application customer's technical experts. Motorola does convey license under patent rights rights others. Motorola products designed, intended, authorized components systems intended surgical implant into body, other applications intended support sustain life, other application which failure Motorola product could create situation where personal injury death occur. Should Buyer purchase Motorola products such unintended unauthorized application, Buyer shall indemnify hold Motorola officers, employees, subsidiaries, affiliates, distributors harmless against claims, costs, damages, expenses, reasonable attorney fees arising directly indirectly, claim personal injury death associated with such unintended unauthorized use, even such claim alleges that Motorola negligent regarding design manufacture part. Motorola registered trademarks Motorola, Inc. Motorola, Inc. Equal Opportunity/Affirmative Action Employer.
reach USA/EUROPE/Locations Listed: Motorola Literature Distribution; P.O. 5405, Denver, Colorado 80217. 1-303-675-2140 1-800-441-2447 JAPAN: Motorola Japan Ltd.; SPS, Technical Information Center, 3-20-1, Minami-Azabu, Minato-ku, Tokyo 106-8573 Japan. 81-3-3440-3569 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre, King Street, Industrial Estate, N.T., Hong Kong. 852-26668334 Technical Information Center: 1-800-521-6274 HOME PAGE:
Motorola, Inc., 2001
AN2158/D More Information This Product, www.freescale.com

AN2158 Freescale Semiconductor, Inc. Designing with MC68HC90

Top Searches for this datasheet

Other recent searches