ESP32S2: Add AnalogIn

[hierophect]

This PR adds the AnalogIn module to the ESP32-S2 port. The IDF documentation underlying this module can be found here. The ESP32-S2 has more limited configuration options than the ESP32 for its ADC, so we assume the default settings of 13 bit width for measurements and an attenuation of 11DB for the maximum voltage range.

Also unlike the ESP32, the S2 appears to have a hard cap of 2.6V maximum for ADC readings, even at the max attenuation settings. I've asked Espressif whether this is a hardware limitation, or whether it will be raised as the S2 support matures.

This PR requires #3492 for access to the ESP_ADC_CAL component of the ESP-IDF, so it should not be merged until that is submitted. Reviewers may want to hold off until that PR is complete if they want to avoid viewing duplicate changes.

Tested on a Saola 1 Wrover on a 10k pot with a multimeter control. Accurate to ~0.1V up to the max of 2.6V.

[UnexpectedMaker]

Oooer, I was about to ask about this today!!!!
I need AnalogIn for my FeatherS2 - as I have the ALP light sensor on board.
Thanks for getting this underway @hierophect !

[anecdata]

Unless I'm reading the API Reference wrong, ESP32-S2 ADC1 and ADC2 will allow full-range voltage, but Espressif says most accurate readings at 11dB are between 150 ~ 2600mV (better linearity at the high end than ESP32).

11 dB attenuation (ADC_ATTEN_DB_11) gives full-scale voltage 3.9 V (see note below)

Note
At 11 dB attenuation the maximum voltage is limited by VDDA, not the full scale voltage.

SoC | attenuation | suggested range (mV)
ESP32-S2 | 11  | 150 ~ 2600

[tannewt]

Thanks for switching those headers! Just a few questions.

[tannewt]

Replied to the unresolved comments.

[hierophect]

@tannewt I removed the logging from shared-bindings - however, we could alternatively add a common-hal-log function to common-hal/microcontroller and use that, to keep things encapsulated?

[hierophect]

CI is being flaky, it's failed random boards a couple times in a row now. I don't think there's anything actually wrong with this.

[anecdata]

Githib actions degraded https://www.githubstatus.com

[tannewt]

Please update this now that the IDF switch is merged.

[tannewt]

Looks good overall! Just a couple questions. Thanks!

[tannewt]

Thank you!

[kevinjwalters]

What's the conclusion to all this? I've got a FeatherS2 running 6.1.0-rc0 which can't get above 52149 (0b1100101110110101) on A1. A Feather nRF52840 Express alongside gets to 65520 connected to same pot.