An edge board containing five opto isolated inputs. All inputs are active HIGH. Each input comes with an input pin, a 5v and a gnd connection.

If I were to do this again, I would probably make a jumper that can switch between the 5v and whatever the bus voltage was.

source files can be found here: https://github.com/evezor/v0_5up_digital_input_board

This board uses the Evezor Stamp STMF405 MCU

source: https://github.com/evezor/Evezor-Stamp-STMF405