Matrix user forums

Hello,
I've been successfully using my HP-488 Programmer Board with Flowcode to program 16f877a. The nature of the program is to receive ADC input on pin 2 and input switches from Port D and sending out a PWM. Also connected to the HP-488 Board are a potentiometer to generate the ADC input on Pin 2 of the IC and the Switches just wired to the particular pins on the board.
This way after programming, I test the IC with a potentiometer on this board checking it with an oscilloscope. I have programmed and tested over 30 ICs already just changing the duty cycle.

Suddenly, when I program it again for the nth time, I get PWMs that are all messed up. Full 255 duty cycle are changing. Duty cycle of 30 has spikes. I also tried other simple programs and they all do the same thing.

I tried to program another IC with less pins 16f88. The program works but if the program needs to generate PWM, it again does not generate the correct PWM out.

Did I somehow damage the board? How? I'm getting an EB-006 and I dont want this to happen again to the new one.

Hello

It does not sound like board damage if only the PWM is effected. Could it be that your component code file has been altered or corrupted in some way?

Do you have an older previously working chip to test that still has the old compiled code running on it?

A previously compiled chip fading LEDs works on the board but previously complied chip with PWMs don't work either. I noticed some scratches on the board. I think we may have scratched the board. Do you think that's it? Do I say good bye to my board? Luckily I was able to buy an EB-006 through a very kind local distributor who was willing to sell it to me after business hours!

Hello

Scratching the board should not cause a problem, when I have to do mods to boards it normally takes a sharp knife and a bit of elbow greese to get the tracks to move.

However if you have broken or shorted a track then yes this could well be the reason for your faulty PWM.

Can you try outputting normal digital 1s and 0s on the PWM pin using the output icon and see if you can measure the output voltages. If you can then the board is ok. If you cant then see if you can spot any problems along the tracking for those I/O. A multimetre with conductivity testing will work well for this.