Wiring a microcontroller into a PCB from a separate PCB...Noise issues?

[treez]

Hello,
We have just designed a prototype 60W isolated offline SMPS LED driver using a single stage Flyback.
At the moment we are just running it at fixed 60W power output because we did the microcontroller footprint wrong and so there’s no micro on the board. (the micro should do the dimming via received DALI messages).
Anyway, we wish to get around this by having a microcontroller on a separate PCB which we will now make up, and then we will wire from this PCB, onto the main PCB. (just for the prototype).

Anyway, do you think this sort of wiring will likely be too problematic due to noise issues?

I mean, we will wire each connection using twisted pair and take a ground with each signal so as to reduce noise issues, and also have capacitors right at the microcontroller pins if the pin is an input…..but do you still think this is unadviseable due to noise issues?. The micro will run at 32MHz using its internal clock.

The inputs to the micro from the main PCB are….

1…DALI signal at 1200Hz.
2….Temperature signal (analog voltage)
3….LED current signal…(analog voltage)


The outputs from the micro to the PCB are……

1…..PWM dimming signal at 1kHz
2…Shutdown signal…..(Digital I/O)

 

[betwixt]

As long as you follow good supply decoupling practice AT THE MICRO, and ensure it's clock signal is clean, you shouldn't have any problems. If the micro uses a crystal for it's clock, keep it (or duplicate it) at the micro end. Obviously keep the ground at low impedance by using more than one parallel wires to minimize inductance. The other signals are slow so noise shouldn't be a problem.

Brian.