nrf52 obtain battery level using internal bandgap (sdk 14)

[MattFL]

Can anyone give me a tip on porting the code below, which works great in sdk12, to sdk14?  I'm using the nrf52832 and the ble_app_hids_keyboard example and need to get a real battery level measurement.  The code below was originally found here.  

#define VBAT_MAX_IN_MV                  3000
uint8_t battery_level_get(void)
{
  // Configure ADC
  NRF_ADC->CONFIG     = (ADC_CONFIG_RES_8bit                        << 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);
  NRF_ADC->EVENTS_END = 0;
  NRF_ADC->ENABLE     = ADC_ENABLE_ENABLE_Enabled;

  NRF_ADC->EVENTS_END  = 0;    // Stop any running conversions.
  NRF_ADC->TASKS_START = 1;

  while (!NRF_ADC->EVENTS_END)
  {
  }

  uint16_t vbg_in_mv = 1200;
  uint8_t adc_max = 255;
  uint16_t vbat_current_in_mv = (NRF_ADC->RESULT * 3 * vbg_in_mv) / adc_max;

  NRF_ADC->EVENTS_END     = 0;
  NRF_ADC->TASKS_STOP     = 1;

  return (uint8_t) ((vbat_current_in_mv * 100) / VBAT_MAX_IN_MV);
}

[Andre]

It looks like you're accessing the peripherals directly, so, not using the SDK, but only the MDK. That would mean this code would run without any adjustments.

[Edvin]

That is correct. What you are using in the snippet above is not SDK dependent, so it should be the same in SDK14. Have you tested it? Did it not work?

 

BR,

Edvin

[MattFL]

Thanks guys for the replies.  After looking closer, I see what you mean that the problem is not a difference in sdk, but instead a difference in platform.  I was in a hurry and when it didn't compile I jumped to the conclusion that it was very different, but after looking closer maybe it's not so different.  The code above works on the nrf51 and uses  NRF_ADC_Type to configure the ADC, but I need it to work on the nrf52 where NRF_SAADC_Type is used.  So perhaps I just need to port the settings over to NRF_SAADC_Type.  I'll give this a shot and post my code if it works.  

[MattFL]

As a relative newbie to Nordic, configuring the nrf52 saadc to behave like the nrf51 code above was requiring more reading than I have time for at the moment, but I stumbled upon the eddystone library and used es_battery_voltage_get() from there, which seems to have done the trick.