For the past 6 months I have a circuit on a breadboard consisting of a microcontroller and LCD was working...recently my code would download, but the microcontroller would not execute the program (since yesterday)...its like it is frozen and none of the pins do what its meant to do....some pins are outputting rubbish but periodic signals that dont mean anything...I dont know whats wrong, I replaced the microcontroller with brand new ones, and still all of them are giving the same problem....I pressed reset, turn the power on and off and what not.
I have checked my oscillator circuit, replaced the crystal...probed with logic probes and osciolloscopes here and there to no avail.
Usually, a problem can be solved after time...but this one, spending hours and still cant figure out whats going on here. Could it be something so trivial and so under my noise that Im overlooking it?
Any ideas? The microcontroller is an 8051 if anyone is interested.