Programming problems for PIC12C508A - help please . . . .

[Y C Lui]

Hello,
I am having big troubles in programming the PIC12C508A and will very much appreciate some helps. I have already killed two chips ( well . . . they looked quite "dead" to me . . . ) in my programming attempts. The history is as follows:

binary file used : \FMS\Doc\Interface\firmware\12c508.hex

1st attempt : I asked help from my colleague who did the programming with a universal programmer. It failed as I could not get any signal out from pin7 of the chip ( it stays constantly at +5V )

2nd attempt: I decided to build my own programmer according to the instructions given in a link provided in the FMS documentation < >. The programming utility used was P50XV22.ZIP (32K) <p50xv22.zip> downloaded from the same site. Before plugging in the chip, I have checked for the presence of programming signals at pin 7 ( GP0 ) and pin 6 ( GP1 ) by using a oscillosope and everything looked just fine except that the programming utility gave a message "verify : FALSE" after the completion of programming. At first I thought it was due to the absense of the chip but I still got the same message after programming was done with the chip in place. This attempt failed again as there was no signal out from pin 7 except for a constant +5V (


I really don't want to keep on killing chips although they are inexpensive, any advice before my third programming attempt will be very much appreciated.


Thanks,

Y C Lui
from Hongkong

[Baumgartner]

Dear Lui!

Look at my homepage . The interface section is written in german but follow the links an you will get all the answers of your problems.

never stop flying FMS Andreas

[Steve Lewin]

It's quite usual to get a "Verify Fail" with a 12C508 unless the programming software is reasonably sophisticated. They don't actually behave precisely as the specifications suggest when using the internal oscillator (as in this circuit). Usually they have programmed o.k. it's just the verify check that fails.

Are you sure it's the PIC that's wrong ? How have you checked the rest of the circuit ? Is there a clean signal on the input to the PIC ? Are you sure the transistors are o.k. etc ?

Steve