>At 11:39 AM 12/5/97 +0000, you wrote:
>>> My idea as well, and i might add to that, a simple logic probe
>>> available for a couple dollars from radio shack/ tandy usually works
>>> out great
>>
>>
>>
>>Before I was able to get an emulater (ICEPIC in my case) I was
>>stumped as to what was going on inside my PICs.  I built a crude
>>in-circuit tester consisting of a 1K resistor and an LED connected to
>>each port pin.  A set of DIP switches connected each LED to the pin,
>>or not.  I found this to be very usefuil in figgerring out what was
>>going on inside a circuit.  On simple one and two output designs, I
>>could use PORTA as the I/O, and the entire PORTB was used as a
>>diagnostic output.  For instance, you can watch a counter increment
>>or have the program put a variable out on PORTB to check it's value.
>>
>>I think this was a great project for a beginner.  After purchasing an
>>emulator I'd never use it again.
>>Best Regards,
>>
>>Lawrence Lile
>>
>
>Another more advanced but not very expensive tool which has been
invaluable to me in very complex microprocessor circuits is a simple FIFO.
There are static 1k 8bit or 16bit FIFO buffers available which have a
simple write enable/increment pin interface. For example: take an 8 bit
1kbyte FIFO and hook 8 LEDs to its outputs, a switch to its reset pin, a
debounced switch to its increment pin, and its inputs to an 8-bit bus that
you want to debug and its increment pin to a pin which pulses on the bus
when each byte is sent. This way, you can generate a "log file" of the last
1024 bytes sent over the bus and step through them at your leisure.

Sean

+--------------------------------+
| Sean Breheny                   |
| Amateur Radio Callsign: KA3YXM |
| Electrical Engineering Student |
+--------------------------------+
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