Which programmer to buy to find nasty PIC16F877A bug

[carterson2]

Hi,

I buy PIC's from modtronix, so I use the bootloader, CCS compiler and lots of printf statements!

I attached an SD card to a SBC44B which works great 99.999% of the time.

I have spent over a year trying to find that .001% bug.

Q: Any suggestions on how to find it? What to buy and why?

thanks
jim
http://www.gpscruise.com

[sk_uk]

Can you give a detail description of the bug?

[carterson2]

Its a datalogger.

When you push a button, it writes the gps-location to the SD card at SD-block-location=counter,
then decrements counter and writes it always to block 1 on the SD card.

Sometimes it writes all zeroes instead of lat,lon.
Sometimes the counter decrements by more than one.

but this only happens every 1000 times.
I share RAM alot. Eg, I use unions to reuse RAM, so I figured that was suspect,
but not sure which emulator to buy to set-a-breakpoint on the event...

thanks for any help.
-jim

[sk_uk]

Have you got the source code we can have a look at?

[carterson2]

Probably not. At present, I protect the sourcecode. Its my only value added... I cant afford patents...

I have an opensource version, but it doesnt use the SD card, only EEPROM..

Anyway, do you have any suggestions on debuggers I might use??

[epizido09]

when it comes to that extremely nice C compiler that does that "knocks hand-writtenoptimised assembly into a hat", can i ask ya what compiler it is???  thanks