why saadc value is correct only device contected

[fanleung]

Hi,Everyone! Now i have the board nrf52832 and i'm trying to get the battery value and send by using saadc. i have read the example of ble_app_proximity and saadc,and i configure it by my thought, here is my configuration:

    void Battery_Update(void)
 {
    nrf_saadc_value_t adc_result;

    nrf_saadc_enable();

    nrf_saadc_resolution_set(NRF_SAADC_RESOLUTION_10BIT);
    nrf_saadc_oversample_set(NRF_SAADC_OVERSAMPLE_DISABLED);

    nrf_saadc_channel_config_t config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);
    ret_code_t err_code = nrf_drv_saadc_channel_init(0, &config);
    APP_ERROR_CHECK(err_code);

    nrf_saadc_buffer_init(&adc_result, 1);

    nrf_delay_us(100);
    nrf_saadc_task_trigger(NRF_SAADC_TASK_START);
    nrf_saadc_task_trigger(NRF_SAADC_TASK_SAMPLE);

    while(nrf_saadc_busy_check());

    nrf_saadc_disable();

    if(BLE_GetBattery_Level_notify()){
        BLE_Battery_Update(&adc_result, 2, NULL);
    }
    printf("adc_result: %d\r\n", adc_result);
 }

this function will be operated per 1s, and the result is:

1. not contected, adc_result: 27248(always this value)

2. contected,but not enable characteristic notify, adc_result: 0(always this value)

3. contected,and enable notify, adc_result is correct.

i'm confused what happen and how to solve it. i need your help! thanks!

[FormerMember]

Can you see what happens when you make adc_result a static variable or take it out of the function to make it a global variable?

[fanleung]

Dear Raj, thank you for your answer! Both i make adc_result a static variable or glabal variable, the adc_result is correct!! Could you tell the reason? thanks a lot!