grounding question r/ tactile switches and LEDs

[cantgetnosleep]

Hello all,

I'm designing a PCB to hold approx. 16 tactile buttons and LEDs. My question concerns grounding. I'm wondering if I can simply create a ground plane on the PCB and tie all of the LED and switch grounds to the same plane, and return this to a common ground with the DIN and DOUT grounds. By this I mean: combine the LED and switch grounds on the PCB and run a heavy-gauge ground wire to a common ground on another board, likely the PSU board somewhere (near where the DIN and DOUT board grounds connect).

Or, do I need to group the grounds for each bank of 8 switches and LEDs and return this ground back to the DIN and DOUT modules, keeping the LED grounds and switch grounds separate, and keeping each set separate as well.

Obviously if I can combine the grounds this makes routing the PCB MUCH easier. However, I'm wondering if there's a reason not to do this.

Thanks - Andrew

Edited June 4, 2010 by cantgetnosleep

[Wilba]

You can tie all the LEDs and switches to a common ground plane. You don't need heavy-gauge wire between the boards, one wire of a ribbon cable is enough.

Since 16 (or 8) matches the number of inputs/outputs of DIN/DOUT modules, you might want to consider putting the shift registers on the same board as the switches/LEDs... then you'll only need 6 wires to connect these boards to a Core (or together)... otherwise you'll need to connect 32 wires (+ground) between these PCBs and DIN/DOUT modules. It's not much extra routing. This only works if you have enough room for the ICs, resistors and resistor networks.

[cantgetnosleep]

Thanks for the quick reply. I was hoping I could tie the grounds together--it definitely makes things simpler. Moving the shift registers onto the boards is a great idea, but I'll have to see if I can squeeze the parts onto the boards, or maybe I'll finally spring for the non-profit version of Eagle so I can make larger boards. Hmnmm.

Cheers - Andrew