Battery service outputs 100% no matter what

[Mathias Vandel]

Hi DevZone

I am trying to measure the battery voltage using the bas service. I got some hints from the ble_app_proximity example.

My problem is that no matter what the output is 100% (And yes it is tested on a CR2032 with 2.8V, so it should be more like 30%ish).

My saadc event hander is:

void saadc_event_handler(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        nrf_saadc_value_t adc_result;
        uint16_t          batt_lvl_in_milli_volts;
        uint8_t           percentage_batt_lvl;
        uint32_t          err_code;

        adc_result = p_event->data.done.p_buffer[0];
					
				SEGGER_RTT_printf(0, "adc_result: %d\n", adc_result);
        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, 1);
        APP_ERROR_CHECK(err_code);

        batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_result) +
                                  DIODE_FWD_VOLT_DROP_MILLIVOLTS;
        percentage_batt_lvl = battery_level_in_percent(batt_lvl_in_milli_volts);
						
        err_code = ble_bas_battery_level_update(&m_bas, percentage_batt_lvl);
        if (
            (err_code != NRF_SUCCESS)
            &&
            (err_code != NRF_ERROR_INVALID_STATE)
            &&
            (err_code != BLE_ERROR_NO_TX_PACKETS)
            &&
            (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
           )
        {
            APP_ERROR_HANDLER(err_code);
        }
    }
}

and the adc initialization:

static void adc_configure(void)
{
	  ret_code_t err_code = nrf_drv_saadc_init(NULL, saadc_event_handler);
    APP_ERROR_CHECK(err_code);
    
	nrf_saadc_channel_config_t config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);
    err_code = nrf_drv_saadc_channel_init(0, &config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(&adc_buf[0], 1);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(&adc_buf[1], 1);
    APP_ERROR_CHECK(err_code);
}

The result in nRF connect:

Can anybody point me in the right direction? I am a bit lost where my problem is.

Btw. I am using the PCA10056 (NRF52840 PDK) and SDK12.20 :-)

Best Regards Mathias

[Mathias Vandel]

Sorry, but i am a little confused over the notification thing. Where should i enable notifications? Is it in my bas_init?

    static void bas_init(void)

{ uint32_t err_code; ble_bas_init_t bas_init_obj;

memset(&bas_init_obj, 0, sizeof(bas_init_obj));

bas_init_obj.evt_handler          = on_bas_evt;
bas_init_obj.support_notification = true;
bas_init_obj.p_report_ref         = NULL;
bas_init_obj.initial_batt_level   = 100;

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&bas_init_obj.battery_level_char_attr_md.cccd_write_perm);
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&bas_init_obj.battery_level_char_attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&bas_init_obj.battery_level_char_attr_md.write_perm);

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&bas_init_obj.battery_level_report_read_perm);

err_code = ble_bas_init(&m_bas, &bas_init_obj);
APP_ERROR_CHECK(err_code);

}