it might work to your needs, but if you modify your code, you need to keep in mind some things.

1. ALWAYS terminate your code. I wouldn't even trust that the assembler's END statement would properly terminate your code.

So, to be absolutely certain that your code is terminated properly, add a line that causes an endless loop. You can use "ljmp $", "ajmp $", or "sjmp $". For beginners, LJMP is the best because there are fewer restrictions when using it.

2. Check your memory. Make sure that you have enough space to store your code. It is easy to write a program that exceeds 2K.

3. Clear all the registers that could potentially screw you up later. In another words, do NOT make assumptions. Make facts. Initialize everything you use.

Here is an example.

If you had code like this:

djnz R5,$
ajmp $

and you expected R5 to count from 255 to 0, then if someone came along and pressed RESET, then your count might be off because part of the internal memory does not clear out on a reset.

So you will need to use this instead:

mov R5,#0h
djnz R5,$
ajmp $

That way, when reset is pressed, R5 will be guaranteed to have a value of 0. Now R5 can count from 255 to 0.


As for the hardware, Make sure that all connections are secure. Even a loose connection can create problems.