i2c 8 channel IO board with relays

With all these MCU’s needing to connect to real world stuff.. electric valves, heaters, motors and the like. I need a versatile IO board that I can hook up to an Arduino, Raspberry PI, Beaglebone or Carambola.  All of which have an i2c bus. So armed with a MCP23017, I’ve come up with this IO board.

  • 8 Relay outputs ( relays are spec’ed at 240V 5A )
  • 8 Digital inputs ( switched input, closing to ground )
  • Selectable i2c address ( up to 8 of these on the one i2c bus )
  • All running from +5V ( relays can be powered from an alternative power supply if 5V coils are not to hand )
  • Single layer, through hole construction ( old skool! )
i2c Relay Board - schematic

i2c Relay Board – schematic

I’m loving KiCAD… Over the last few schematic captures I now have a handle on libraries, this time I got my head around modules as I couldn’t find the pads for the relays I wanted to use.  Even better, I managed to layout the board on a single sided PCB! Here it is:

i2c Relay Board - PCB

i2c Relay Board – PCB.

All the files are here: i2cRelayBoard

Now I’ve got to get all the clobber to make my own PCB’s… It’s been a while since I’ve had to do that…!

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