Proposal: add async digital traits #649
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As discussed in #647 and on the rust-embedded matrix, the digial traits mean that IO expanders currently need to block.
Also I am working on a library for turning an MCU into an IO expander (no public code yet, still very WIP), and accessing the IO behind that MCU would need to block. The amount of blocking could be significant given that my library will be usable from over SPI to Ethernet.
Currently the proposal just takes the traits in
embedded_hal::digital, copies them and adds theasynckeyword in front of each function.There are also some comments relating to what
Poll::Readymeans. The documented semantics are that whenPoll::Readyis returned, whatever operation is involved has completed. So if a pin is set to a high level, whenPoll::Readyis returned, the pin will be driving a high level.The 2nd commit changes the docs of the blocking
digitalmodule inembedded_halto mention that the traits are blocking (always have been).I also hacked together a quick test with
postcard-rpcto blink an LED over USB to show an implementation of this for at leastOutputPin. There is some extra stuff I did throw in but it is unused: https://github.com/i509VCB/postcard-gpio-test/tree/masterResolves #647