Pin for ADC configuration

[kvrb]

Hi

I am looking for pin numbers for the nRF51822 microcontroller.

example like what are the pin numbers for VDD to measure battery voltage..??

I mean in which header file it was defined..? We have custom nRF51 boards.

[Sigurd]

You can find the pin numbers in the Product Specification (Chapter 2.2).

In order to measure VDD using the ADC:

1. Choose VBG as reference voltage. This is an internal 1.2V reference voltage.

2. Use NRF_ADC_CONFIG_INPUT_DISABLED to disconnect the analog inputs on the GPIOs.

3. Use "Supply one third prescaling" as input. This will connect VDD/3 to your ADC.

Now you can measure VDD without any external components at all.

At the Nordic Semiconductor GitHub page, we have an example that does this: github.com/.../ble_app_hrs_adc_battery_measurement

[Sigurd]

Note: In the example you need to uncomment line 1019 and 1020 in main.c, to sample the supply voltage of the nRF51 directly (not from a pin)