Program Erasing

[evaradharaj]

Hi,

I am using 16f877a microcontroller. I programmed the IC before one week. Today, the program was erased without any sudden change. Can you tell me what is the problem?

I experienced this problem many times. I am using LCD. After Reprogramming its working fine. If program erased means, the LCD is going Black for one line.


Thanks in advance.
_________________
embedding innovation in engineers

[SherpaDoug]

Is just a part of the program getting erased?

What hardware are you using to do the programming?
_________________
The search for better is endless. Instead simply find very good and get the job done.

[Gav Pinto]

[Gav Pinto]

[Ttelmah]

Lets put this slightly into perspective.

First, are you sure the chip is getting erased?. Have you actually put it into a programmer, and read it back to see whether the program is still there?. The 'single black line', just means it is not getting initialised. While loss of program could cause this, so could many other things (MCLR floating etc....).

Now, erasing the program memory could occur in certain situations:
1) Obvious one - you are writing to the memory in your program, and get it wrong.... Does your code write to the program memory?.
2) MCLR gets raised to a voltage significantly _above_ the normal supply rail. This can trigger a 'program' cycle, and result in program erasure. What is connected to MCLR?.
3) The chip is losing it's memory contents because of too many write cycles. This comes back to '1'. If you are writing to the program memory in code, you _must_ remember that this memory has a limited 'write life'. If you have code that updates a value stored in program memory at rapid intervals, then 'think again'. The program memory is not designed for this. It's write life, can be as low as 10000 cycles. If you write repeatedly to the chip, you can kill the chip in under 40 seconds....

If none of these apply, then the comment 'contact Microchip', already made by another poster, applies.

Best Wishes

[evaradharaj]

Thanks for your suggestions.... I'll look at the problem clearly and contact Microchip.
_________________
embedding innovation in engineers