Expander shield

Hey i've been looking for an i/o expander for my uno.Seem like the only thing i can find is a sensor expander for the mega.Anyone knows where i can find an expander so i have more i/o digital/analog on my uno??

Generally outputs are expanded with shift registers and inputs with multiplexers. Which one do you want to do? Do you expect that someone has made a shield to match your specifications? Probably not.

Try to find an online tutorial that describes how to do it for your actual problem (input or output) then use a proto-shield to build the circuit that you need.

Connect to this?

Connect to this?

Great idea. I like it.

However, in general I would still use traditional i/o expander. It's the best performance.

Could use SPI @ 4MHz clock rate to connect the UNO to the Pro Mini. Could read/write to a full port on the Mini in one clock cycle, transfer data at 4M bits/sec. Get additional digital I/O, PWM, analog, serial. Can offload some code onto the second MCU and improve application performance.

I see ok i really though by now someone would have built and i/o expander.Well i like that whole idea of sending code by port to the mini uno.I will have to check on that look pretty complicated.

Some different I/O expander boards here (I2C and SPI).
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