Can I measure battery level without any external components nrf51

[Mikhail]

I want to undestand this. I can't see any examples with it. In the example ble_app_proximity I always received 100% level. If it possible, can anybody give a ADC config example for it? Thanks.

[endnode]

Read this.

[Jørgen Holmefjord]

There was no ADC driver in SDK 9, this was first added in SDK 11. Only HAL driver is available. You need to add ADC driver from SDK 11 to SDK 9 (I think this should work without modifications), or migrate to at least SDK 11. You can also use the ADC HAL driver as shown in the ADC HAL example.