I'm working on an I/O board that goes from serial up to 24 Opto22 compatible I/O modules. So far it is configurable to have any point be an input or output. The problem is that if the user needs 24 outputs, and all on at the same time, the microcontroller can't drive that many 12mA outputs.
I need something that can output 5V at approximately 20mA but can be used as an input if the microcontroller pin is configured for input. Maybe bi-directional self switching transceiver?
Thanks!
RogerN