Hey guys,
I'm going to be submitting this PCB to the board house today to get it made, and at the last minute I'm wavering over whether I should isolate the power pins on my IO ports along the left side of the board.
You can see along the top I have a connection for power and a mosfet for switching it, and thick traces for said power. I also have power and ground planes covering the entire board. But the IO pins along the left side may be carrying large noisy currents, like servos and motors. Now, I have not had any issues in the past with servo noise messing with my components, but I want to design the board as best I can and minimize the chances of any noise making it into the audio portion of my circuit at the lower right.
Adding new planes under the 5V and GND pins on the right is easy enough, but I can't decide if I should do it. I know that signals like to return along the same path they traveled, and in the case of my IO pins, there's two signals. There's the power being drawn, and there's the control signals from the microcontroller. Both of those will be competing for power and gnd.
If I do nothing, I'm sure that won't hurt the high current stuff. But if I isolate the pins, then the signals with a couple wide traces at the top of the board, and maybe a couple for the analog pins down the bottom just to be safe there as well, then the signals from the microcontroller will have to travel in large loops.
So what should I do? I can't both isolate the 5V and GND pins, and have short return paths for my signals. Not on a board this small anyway.