async ADC read

[jounathaen]

Hi,
I'm not so deep in the esp32's internals and also not in the code of the HAL, but I wondered if the ADC reading could be made async.

If I read the docs correctly, one basically has to use nb::block for a read, probably wasting a few hundred/thousand cycles in the process.

[jessebraham]

Based on a quick skimming of the TRM (for the C6, at least) it appears that this should be possible by configuring APB_SARADC_ADC_DONE_INT, which "triggers when the ADC completes one data conversion". As long as we have an interrupt we can create a future for it.

Also thank you for pointing this out, this is very valuable feedback! It's easy to overlook things like this :)

[lu-zero]

I just stumbled upon this problem. I wanted to have an embassy wifi example returning its battery status and nb::block does not look like it can be used.

[nan-mu]

I also don't know much about the specific operation of adc. I want to ask, can't we simply use the current read_oneshot to encapsulate a future? I will post an example later.

Update:
Failing that, it seems like nb is refactoring their future macros, and then, I can't wrap read_oneshot without using unsafe

[nan-mu]

I'm wondering if we could have the ADC own all the pins it needs? That might make it easier to do asynchronous stuff, but it might complicate the type declaration.