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Hi there!

I have a TinyZero connected to a small LiPo battery. I would like to read the current capacity of the battery to the Serial Monitor. Since the board is based off of the Arduino Zero (and by extension, the MKR Zero), I sought to read the value of ADC_BATTERY and convert this value to my voltage reading. The following tutorial shows how to measure battery voltage using an MKR Zero. (https://projecthub.arduino.cc/Arduino_Genuino/mkr-zero-read-battery-voltage-e31f42)
Sprunki Game
When verifying the code for the TinyZero, I receive an error that tells me that ADC_BATTERY is not defined in this scope. However, if I verify the exact same code for an MKR Zero, I receive no compilation errors. Since they use the same processor (SAMD21), wouldn't both boards have an ADC_BATTERY pin, and potentially be able to use ADC_BATTERY the same way?

Thank you for any help!

ADC_BATTERY is not a SAMD21 hardware feature but a board variant alias. MKR boards define ADC_BATTERY in their variant so analogRead(ADC_BATTERY) works. TinyZero's variant does not expose ADC_BATTERY so the symbol is undefined. Fix it by checking the TinyZero schematic to find the ADC pin used for battery sense and then use analogRead(thatPin) or add a simple resistor divider to a free analog pin and read that. See MKR variant examples and TinyZero docs for the pin/schematic references.