programming the pic 16f877a

[crocklip]

Hi,

I wrote some code for the 16f877a and simulated the program with pic simulator ide which seemed to yield successful results. However when I programmed the chip with a datman 48uxp universal programmer and tested it I got no response at all. the chip was completely dead! I tried again with a spare chip, same model but got the same results. I am using a 2.4576MHz crystal and so set the programmer to xt osc. mode. I have had this same problem for 2weeks now and cant seem to find the problem. Any help from you guys would be great!
Thanks

 

[Jack// ani]

Well.....with the given clues, no one can exactly answer you, try posting your schematic.

Good luck

 

[philba]

a schematic would help but here's what I would do:
- verify that the chip programmed by reading it back.
- get an o'scpe and look at the osc pins (w/high impedence probe). is it oscillating?
- create a very simple program that toggles a single pin every second or so. look at that pin with a dvm (or an led).
- make sure that you've got power (+5V), ground and mclr pulled high (10K is good).
- also, make sure you've turned off the watchdog timer. I had a project that seemed dead but was constantly resetting because of the wdt.

 

[crocklip]

thanks Philba, turns out I didnt pull the MCLR high. silly me! Now all I have to worry about is mistakes in the code!