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.

[Mikhail]

Looks work. code from here: developer.mbed.org/.../

void my_analogin_init(void)
{
NRF_ADC->ENABLE = ADC_ENABLE_ENABLE_Enabled;
NRF_ADC->CONFIG = (ADC_CONFIG_RES_10bit << ADC_CONFIG_RES_Pos) |
                  (ADC_CONFIG_INPSEL_SupplyOneThirdPrescaling << ADC_CONFIG_INPSEL_Pos) |
                  (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos) |
                  (ADC_CONFIG_PSEL_Disabled << ADC_CONFIG_PSEL_Pos) |
                  (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos);

}

uint16_t my_analogin_read_u16(void)
{
NRF_ADC->CONFIG     &= ~ADC_CONFIG_PSEL_Msk;
NRF_ADC->CONFIG     |= ADC_CONFIG_PSEL_Disabled << ADC_CONFIG_PSEL_Pos;
NRF_ADC->TASKS_START = 1;
while (((NRF_ADC->BUSY & ADC_BUSY_BUSY_Msk) >> ADC_BUSY_BUSY_Pos) == ADC_BUSY_BUSY_Busy) {};
return (uint16_t)NRF_ADC->RESULT; // 10 bit

}

is it correct settings for ADC for my case?