Multiple Digital Outputs & Inputs

Projects General Guidance
1

Looking for some hardware guidance.

I'm looking for a way for a CPU to support approximately 20 Relay outputs and 12 12v Digital Inputs. I would assume that there is SPI Digital input and Relay output cards out there that pcb's to do this. Looking to do this low cost solution. Only ones I seem to be able to find are all direct access and there is not enough IO on the CPU for the count. Also it would make wireing simpler.

Andy

2

You can easily increase the digital I/O pins with shift registers or I2C port expanders.

3

A Mega has enough I/O for your needs.