Using ADC to measure battery voltage internally

[Bret Foreman]

Looking at the ADC HAL, I see 8 choices for ADC input, plus a disabled case. Is it possible to choose as the input to the ADC a node that is proportional to the VCC battery voltage? In other words, I want to measure the battery voltage without adding any external wires. Is this possible?

[Stefan Birnir Sverrisson]

Hi

You choose the analog input pins in combination with one of the three

NRF_ADC_CONFIG_SCALING_INPUT_FULL_SCALE
NRF_ADC_CONFIG_SCALING_INPUT_TWO_THIRDS
NRF_ADC_CONFIG_SCALING_INPUT_ONE_THIRD

but you can also choose one of the two

NRF_ADC_CONFIG_SCALING_SUPPLY_TWO_THIRDS
NRF_ADC_CONFIG_SCALING_SUPPLY_ONE_THIRD

which measures the supply voltage directly and not an analog input pin