Problem with PIC16F87

[The Master]

For most of this testing the RS485 chip hasnt been plugged in and the data wires disconnected. When it has been connected up the RS232 to RS485 convertor has been running from the same power supply.

Im pretty sure theres no problem with the RS485 part of the circuit. When the chip starts having a fit during pause commands if i pull the 555 out then it suddenly goes back to normal.

I also tried using the 555 on the breadboard but removing its regulator and connecting the power wires after the regulator on the PCB and that causes problems aswell. It only works when the 555 and PIC have different regulators

[The Master]

Ive just connected the audio amp circuit up and for some reason that causes the PIC to constantly reset too in the same way the 555 does. The audio circuit has some extra capacitors on so i would have thought that should help.

I tried connecting the audio circuit on the same regulator as the 555 and everything works. The only thing i noticed is that i had to change the POT to get the IR receivers to pick a signal up.

So, the 555 and audio circuit both cause problems with the PIC but the IR emitters that use more current than everything else put together have no effect on it. Im really confused

Edit: I just remembered something else too. When i press the button on my smoke machine the PIC resets. Ive had this problem in the past too. I wonder if this problem could be somehow related. The smoke machine is interfering even though its only connected by the mains wires in the house so it seems things can have an effect on the PIC even when in theory they shouldnt

[mackrackit]

Not knowing how mains are wired where you are at but I will guess that there is a problem in the way they are wired at your place.

I had a similar problem at a customers place. A lot of high frequency "stuff" runs (similar to your smoke machine?). After spending time changing the power supply, adding capacitors etc I found the problem was bad or no earth grounds on most of the equipment. Several places the ground wire was connected to the machine but not to a ground rod creating several antennas going several directions.

I went though and fixed and or added the earth grounds and the problem was solved. The false alarms on their security system even stopped. Not sure about that one, just what I was told.

Might not be the problem, but just from a safety side it would be worth a look.

[The Master]

I dont think the 555 problem is caused by grounding problems. Its on the same PCB using the same ground as everything else. The smoke machine itself is definately earthed correctly and ive had the same problem in a few different buildings. The PIC also resets if i plug something like a soldering iron or big transformer in and the ignition on our gas cooker causes a reset too. These things have affected every PIC circuit ive made so i guess they are normal but im just wondering if the 555 is creating a similar kind of interference thats so small that it only causes a problem when its connected to the same power rails as the PIC.