For ESP32 Pico, not all ADC channels can be opened

[devbotas]

Details about Problem

Target: ESP32 Pico

**Firmware image version:1.7.0.2

Worked before? Probably not

Device capabilities output:

Description

AdcController.GetDefault().ChannelCount returns 20, but only first 10 can actually be opened. Opening other fails with CLR_E_PIN_UNAVAILABLE exception.

Detailed repro steps so we can see the same problem

1. Take ESP32 Pico.
2. Flash this program:

        public static void Main() {
            var adcController = AdcController.GetDefault();

            Debug.WriteLine($"AdcController says there are {adcController.ChannelCount} channels. But can we use them all?..");

            for (int i = 0; i < adcController.ChannelCount; i++) {
                try {
                    var channel = adcController.OpenChannel(i);
                    Debug.WriteLine($"Yay, channel {i} can be opened.");
                }
                catch (System.Exception) {
                    Debug.WriteLine($"Nay, channel {i} cannot be opened.");
                }
            }

            Thread.Sleep(-1);
        }

Other suggested things

If this is a firmware limitation, then AdcController.GetDefault().ChannelCount should return actually usable number of channels. I assume, 10.

Expected behaviour

Should be able to open all channels that are reported by the Windows.Devices.Adc library.