I am facing a very weird problem, I know it is related to hardware only but I wanted to get some ideas/corrections before I redesign my PCB.
I have 4 x 16F676 as slaves and one 877A. My 877A supplies power to 4 x 676. I know maximum current from 877A should not exceed 125mA in total, and it doesn't, I have checked it.

1) But is it OK to design a circuit in this way?

Secondly, I have 8MHz 2 Pin resonators connected to every 676. I have provided ground to the 8 x 22pF capacitors which are connected to the resonators on the same track which provides common ground to all 4 x 676.

2) Is it OK to provide the ground to the capacitors of the resonators from the same track which is providing the ground to the IC itself?

Thirdly, I have my zero detection circuit which provides pulses to all 16f676. I have one common track from 0-detect circuit which is connected to one pin of each IC.

3) Is it ok to do it this way or I should add some resistance between the signal track and the pic? I have one PIC814 opto for Zero-Detection. The arrangement is simple, Collector is connected to +5V via 4.7K. At 4.7k and collector junction, one track goes to PortA.2 of all 4 x 676. Emitter goes to ground.


My circuit is behaving weird, I can't even explain the behavior because it changes as many times as I power the circuit. I don't know if it because of these factors or not. But I have try and redesign it but I want to know if what I am doing is technically ok or not.


My circuit is the following:
Name: PCB.GIF Views: 770 Size: 54.1 KB

I have simulated the circuit and made it on breadboard and it all works like a charm. First attempt at PCB has failed so hopefully with some useful inputs second attempt should take me forward.