why proximity example shows always 100 battery

RE: why proximity example shows always 100 battery

karan — Tue, 09 Feb 2016 10:15:08 GMT

i found that my battery is providing only 3.18V so no way to excced the power supply more than 3.18v from the ADC is there is any other modifications do i ahve to check out?

RE: why proximity example shows always 100 battery

Ole Bauck — Fri, 18 Dec 2015 13:49:54 GMT

The problem is actually with the battery_level_in_percent(..) function. The battery level characteristic value is the percent capacity that is left in the battery. 100 percent means fully charged, 0 percent means fully discharged, see here. The function calculates the percent from the non-linear discharge curve of a CR2032 battery:

 *           - Section 1: 3.0V - 2.9V = 100% - 42% (58% drop on 100 mV)
 *           - Section 2: 2.9V - 2.74V = 42% - 18% (24% drop on 160 mV)
 *           - Section 3: 2.74V - 2.44V = 18% - 6% (12% drop on 300 mV)
 *           - Section 4: 2.44V - 2.1V = 6% - 0% (6% drop on 340 mV)

When running from usb power, the voltage is higher than 3V and the function will always show 100 percent. If you run it from a battery, the value will probably be less than 100 percent.

Note also that the notification must be enabled (enable services in MCP) for the battery measurements to start (battery measurement timer is started in BLE_BAS_EVT_NOTIFICATION_ENABLED event) and that the default measurement period is 120 seconds, so the value will not be updated at once.

RE: why proximity example shows always 100 battery

monpetit — Thu, 17 Dec 2015 17:24:10 GMT

Well, I'm afraid I don't know other ways. Here is a good document deals with measuring battery voltage: Measuring Lithium battery voltage with voltage divider.

RE: why proximity example shows always 100 battery

karan — Thu, 17 Dec 2015 16:56:03 GMT

so it is mandatory to use only voltage dividers is there isany other ways to measure battery voltage?

RE: why proximity example shows always 100 battery

monpetit — Thu, 17 Dec 2015 15:36:04 GMT

I see. Look at adc_config.reference = NRF_ADC_CONFIG_REF_VBG; In this case, adc measurement range is from 0 to 3.6V. If battery voltage is exceeds 3.6V you have to use voltage divider with resistors.

RE: why proximity example shows always 100 battery

karan — Thu, 17 Dec 2015 15:24:13 GMT

Thanks for your reply but still in the nordic app am getting only 100 percent response and i have connected and tested with battery and usb power supply to see the measurementS am getting 100 only

RE: why proximity example shows always 100 battery

monpetit — Thu, 17 Dec 2015 13:39:16 GMT

Sorry for the confusion, it was my fault for using the example of SDK 10.0.0.

You should use void nrf_adc_input_select(nrf_adc_config_input_t input) before nrf_adc_start().

For example:

static void battery_level_meas_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);
    nrf_adc_input_select(NRF_ADC_CONFIG_INPUT_0);
    nrf_adc_start();
}

Happy coding... :)

RE: why proximity example shows always 100 battery

karan — Thu, 17 Dec 2015 13:21:36 GMT

can you tell me do i have add any information in the ADC configure function?

RE: why proximity example shows always 100 battery

karan — Thu, 17 Dec 2015 13:19:19 GMT

i did not see any lines like that in the ADC configure function

/**@brief Function for configuring ADC to do battery level conversion.
 */
static void adc_configure(void)
{
    uint32_t err_code;
    nrf_adc_config_t adc_config = NRF_ADC_CONFIG_DEFAULT;

    // Configure ADC
    adc_config.reference  = NRF_ADC_CONFIG_REF_VBG;
    adc_config.resolution = NRF_ADC_CONFIG_RES_8BIT;
    adc_config.scaling    = NRF_ADC_CONFIG_SCALING_SUPPLY_ONE_THIRD;
    nrf_adc_configure(&adc_config);

    // Enable ADC interrupt
    nrf_adc_int_enable(ADC_INTENSET_END_Msk);
    err_code = sd_nvic_ClearPendingIRQ(ADC_IRQn);
    APP_ERROR_CHECK(err_code);

    err_code = sd_nvic_SetPriority(ADC_IRQn, NRF_APP_PRIORITY_LOW);
    APP_ERROR_CHECK(err_code);

    err_code = sd_nvic_EnableIRQ(ADC_IRQn);
    APP_ERROR_CHECK(err_code);
}

RE: why proximity example shows always 100 battery

monpetit — Thu, 17 Dec 2015 12:01:50 GMT

Look at the code. It probably says like this:

static void adc_configure(void)
{
    ...
    nrf_adc_input_select(NRF_ADC_CONFIG_INPUT_DISABLED);
    ...
}

Change adc input pin to NRF_ADC_CONFIG_INPUT_0 ~ NRF_ADC_CONFIG_INPUT_7 properly and test again.