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Hardware Support Tips

for EDL (EDP) or hobby

1. Samples

Basic 89c51/52 Circuit This circuit is enough to get the blinking program running on an 89c51 or 89c52	(click thumbnail)
Basic TI MSP430F149 Circuit Could be used as a starting circuit for TI MSP430F149 based projects. I used the low cost JTAG programmer from www.olimex.com. The circuit is also available on their site.

Simple Blink Test for 89c51/52 (805x): (blink.a51)

Asm code, illustrates use of timer and its interrupt to blink ports.

Simple Serial Test (for 805x): (stest2.a51)

Simple Serial port test program in asm.
This program would send "Ha" repeatedly on the serial line, at 9600 baud
Use this program to Check whether your basic Serial Setup/connection is working

C example (for 805x): (recv.c)

An example program in C to introduce some peculiarities of Keil-C cross compiler tools.
The Program waits for a character from PC on serial port, and either opens/closes a door or its lock depending on it. If the sent char is "B" 3 times, sounds an alarm.
Compile this program, and simulate it. Open port 0 window. type capital B 3 times in the serial window, and observe P0.7 blinking. P0.7 was connected to a buzzer in actual hardware.

2. Microcontroller List

Though most EDP projects tend to use the AT89C52. The following microcontrollers are the ones I like. They are all available in Local Market in India. People who need features which are are not in 89c52 (like the most commonly needed ADC), should consider these and other options too.

80C535	By Siemens (Infineon). Really good chip with ADC,	But no program memory. External EPROM needed. About Rs. 400 to 550.
89C552	By Phillips. Good chip with ADC, I2C	But no program memory. External EPROM needed. Rs. 350 types.
PIC16F877	By Microchip. Great chip!! almost everything in one chip. ADC, I2C, EEPROM	But Instruction set and architecture is different than Intel cores. But user can apply his 8085 knowledge and learn it as quickly as one would learn 8051 in edl.
AT89c2051	By Atmel. Cute 20 pin version of 8051, with 2 analog comparators! 2.7 V to 5.5 Operating Voltage.	Obviously, no external memory support and low pin count means for small applications. Rs. 65 types
P89C668	64KB Flash!! 8KB RAM, ISP, In-Application-Programable, upto 33Mhz, I2C, PWM	Rs. 600 types.
AT89S8251	AT89c52 with 2KB EEPROM built-in
APR6016	Not a Microcontroller. But good speech/sound storing chip.
MSP430F149	My Fav. Microcontroller. By TI. 16Bit processor. Ultra low power with almost everything. 12bit ADC, SPI, 60K Flash, 2K ram, 256B EEPROM, RISC architecture! and what not	Architecture and Instruction set is totally different than intel 8051 core. Not available in Local Market. and comes in TSSOP SMD package- hence soldering is not in reach of beginners, thus requires good hardware design in first shot. no external mem support. Supply 3.3V max!

`3. Latest EDL Tips: (were written in year 2001 i guess)`

When Interfacing External Memory to 805x microcontroller, USE 74hc573 Latch, instead of 74LS373 (commonly shown in books) Reason: The 74573 has all input pins on one side, and output on the opposite. Whereas 74373 has alternate input and output pins on each side (this complicates and messes the PCB design)

The pull-up resistor values (SIP) can be 4.7K for pulling up 805x ports
EDL02.PDF - "Using Microcontrrollers in EDP":
The presentation i gave on 5th Feb. 2002

oppcb.pdf - "The PCB Is a Component of Your Op-Amp Design"
By Bruce Carter, Senior Applications Specialist, Texas Instruments, Inc
Good article on design issues of PCB for Op-Amp and mixed signal circuits

Vivek Vaid
vivekvaid<|a-t|>iitb_ac_in

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