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Single digital I/O circuit

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Rikr09

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Hello,

I'm working on a design which i don't have enough slots to add I/O's to the main connector, so i i'm thinking in the possibility of implement a circuit which lets me manage DIGITAL I/O as a single pin(s) controlled by a microprocessor, is to say, i would like to know if it possible to have at the same pin a switchable Digital Input/Output.

Currently i have my Digital Inputs and outputs working differentiate as you can check on the attached image, but as i said before, i would like a design where i can mixed to them in a single circuit.


Captura.PNG


Thanks for your attention and ideas...
 

Digital isolators only go one direction. So you can't use one isolator channel as both an input or output.

It is possible to multiplex multiple signals into the inputs of the isolator so long as you have a way to control or synchronize the mux.

You can also run an SPI GPIO expander through your isolators and expand to many more I/O's (at the cost of speed).

And there are other schemes like running a variable frequency or duty cycle through the isolator to communicate more than 2 states through a single channel.
 

Beyond presently used hardware components, a good starting point would be to define the functionality of the intended bidirectional IO pin. The input and output ports shown in your circuit are not compatible and can't be "mixed". You need something different like an open drain port with pull-up resistor. But we don't know the application and characteristic of connected peripherals.
 

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