Battery Service (BAS) never receiving notification

[xhr0428]

I'm using standard ble_bas from sdk12.3. I set up a timer at 60s interval to use saadc to read battery voltage. Below is my code in saadc event handler for battery level update.

Battery service property has Read and Notify. Using Read, I could get the correct battery level in nRF Connect App. But after notification is enabled, I have never received battery level update. What would be the cause of the issue?

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];

        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);
        percentage_batt_lvl = myBatteryLevel(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);
        }
        // stop saadc to save power
        nrf_drv_saadc_uninit();
        NRF_SAADC->INTENCLR = (SAADC_INTENCLR_END_Clear << SAADC_INTENCLR_END_Pos);
                NVIC_ClearPendingIRQ(SAADC_IRQn);
    }
}

[Jørgen Holmefjord]

Hi,

Do you get any error codes returned from the call to ble_bas_battery_level_update()?

When you read the characteristics, is it updating according to the battery level, or is it always static at the initial value?

Best regards,
Jørgen

[xhr0428]

Hi Jørgen,

Error code is 0, so that's NRF_SUCCESS I believe. 

I set the initial value to be 50% and it returns 78% when I read the characteristics, so it is updating according to the battery level.

Thanks

[Jørgen Holmefjord]

Can you provide a sniffer trace of the on-air traffic between the phone and the board? You can use our nRF Sniffer for Bluetooth LE for doing the sniffer capture.

[xhr0428]

Hi, I exported sniffer packets in the csv file and text file. I removed some packets in the beginning for scanning, connection, service discovery etc. It starts with enabling battery service notification. I only see empty PDUs during the process. 

wireshark.txt

wireshark.csv

[Jørgen Holmefjord]

Looks like the notifications are not sent to the phone at all then. Are you sure that the call to ble_bas_battery_level_update() always return NRF_SUCCESS?

Any specific reasons you are using such an old SDK for a nRF52 series project? Is the battery service working as expected if you run the  ble_app_proximity example?

[xhr0428]

I printed out the error code of ble_bas_battery_level_update. It shows error code 8 for the first time the battery update function is called. All the following prints show error code 0.

The application was made long time ago with this SDK. I'm revisiting to address some issues.

Battery update works with ble_app_proximity example. 

I opened a private case to upload my codes. Case ID is 258031. Please take a look if possible.

Thanks