Expander PI with IO PI Plus
2721 Views - Created 05/02/2016
Is it possible to use 3 IO PI Plus boards AND 1 Expander PI, AND still have access to the PI's 17 IO? From what I've been able to gather I can only use 2 IO PI Plus and 1 Expander or 4 IO PI Plus. There are ways I can make this work with a single RPi if the expansion boards will cooperate.
1- 3 IO PI Plus + 1 Expander PI + RPi 17 pins
2 - 4 IO PI Plus + RPi 17 Pins and some A/D circuitry on a couple of the pins.
I can reduce the number of discrete inputs by using more analog inputs but I'm hitting a wall there as well.
Ideally what I need is 64 discrete inputs, 56 discrete outputs, and 3 analog inputs, but I have some flexibility with the inputs. In some places I can substitute 1 analog input for 2 discrete inputs (travel limits) by using a motor with encoder or fitting the mechanism with a POT for position feedback.
Anyone know of a way to get that many IO from a single RPi?
4 IO Pi Plus boards should work fine in parallel and will give you 128 inputs or outputs. You could combine this with an ADC board to give you the analogue inputs.
One way to increase the number of input pins would be to use multiplexers on the GPIO or IO Pi pins. Something like a CD4512BE or similar logic device would allow you to read 8 inputs using 4 pins effectively doubling the number of available inputs.
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