How do I measure battery level on an Nrf51422 without external components?

RE: How do I measure battery level on an Nrf51422 without external components?

Nero — Tue, 30 May 2017 13:50:09 GMT

Hello ,How Can I use this program with SDK 12

RE: How do I measure battery level on an Nrf51422 without external components?

Mohamed O.Abouzeid — Sun, 27 Sep 2015 00:10:43 GMT

#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);
       }

the only thing you will change is VBAT_MAX_IN_MV as it depends on the battery max voltage level, it uses the bandgap voltage as it will be a constant ref whatever the value of vcc & scale vcc down to be withen 0 to bandgap voltage then it measure the battery level & refer it as percentage of the maximum voltage

try it, I tried it & it works fine with me

RE: How do I measure battery level on an Nrf51422 without external components?

Mohamed O.Abouzeid — Sat, 26 Sep 2015 22:24:47 GMT

I found how to use the adc to measure the vcc but I face some problems, when I finish I'll put the code in an answer comment thanks for your great advice

RE: How do I measure battery level on an Nrf51422 without external components?

Nguyen Hoan Hoang — Sat, 19 Sep 2015 01:17:36 GMT

sure there are 8 add channels and about 30 i/o you can use. I have applications that 3 adc at the same time, other 20 i/o at the same time.

RE: How do I measure battery level on an Nrf51422 without external components?

Mohamed O.Abouzeid — Fri, 18 Sep 2015 23:18:50 GMT

can I use the ADC to sense the battery & to wake up the system on the same application ? ?

RE: How do I measure battery level on an Nrf51422 without external components?

Nguyen Hoan Hoang — Sun, 05 Jul 2015 18:46:36 GMT

look at the adc_simple example in peripheral folder.

RE: How do I measure battery level on an Nrf51422 without external components?

Nguyen Hoan Hoang — Sun, 05 Jul 2015 03:04:26 GMT

There is no addition hardware require. You need to use the ADC and configure it to sense the VCC. This all done pragmatically. There are example code in the SDK. I don't recall which one. Browse through all the examples, you'll find it.