Since the last post, I have been working on getting version 1.0 tachometer board up and running. It turns out that creating the schematic and laying out the board in one night is too fast for a novice like me. I made a number of simple mistakes that doomed the board from the schematic level.
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| Bad Schematic (REV -) |
The two areas boxed in red were incorrect. VDD is positive 5V and VSS is ground. Apparently the PIC16F688 does not work well when it is not grounded properly. However, it does show some life. For whatever reason, I was still able to blink an led. The delay between blinks was 5X slower than it should have been, but it did work. This played havoc with my programming because I was convinced the board was working properly. Finally, after a bit of programming help from the Sourceboost C forum (
my thread), I managed to get Timer 1 working properly. I also have fixed my current board, shown below.
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| Fixed Board |
The schematic has been updated to fix the errors, as well as add holes to connect to the unused pins. I wanted this in order to use the board for prototyping in the future.
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| Updated Schematic (Rev A) |
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| Updated Layout |
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