SAADC Value is not changing as it should

Question

Hello,

On a custom board, using the NRF52832, we want to know the value of a potentiometer. This value is send via a signal on the AIN5 pin of the NRF52.

So, I tried to set up a code to read the value via the saadc module, but it seems it doesn't work as expected...

Here's my code :

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        ret_code_t err_code;

        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
        
        NRF_LOG_INFO("%d\r\n", p_event->data.done.p_buffer[0]);
    }
}

void saadc_init(void)
{
    ret_code_t err_code;
    nrf_saadc_channel_config_t channel_config 
        = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN5);

    err_code = nrf_drv_saadc_init(NULL, saadc_callback);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_channel_init(0, &channel_config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer, SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for application main entry.
 */
int main(void)
{
    bool erase_bonds;
    ret_code_t err_code;
    
    initLeds();
    led_purple();

    // Initialize.
    log_init();

    // Initialize the async SVCI interface to bootloader before any interrupts are enabled.
    //err_code = ble_dfu_buttonless_async_svci_init();
    //APP_ERROR_CHECK(err_code);
    timers_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    storage_init();
    gap_params_init();
    //scan_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();
    peer_manager_init();
    //db_discovery_init();
    //lbs_c_init();
    // Start execution.
    NRF_LOG_INFO("Devroye application started.");
    application_timers_start();
    //scan_start();

    advertising_start(erase_bonds);
    
    saadc_init();
    
    // Enter main loop. 
    for (;;)
    {
        nrf_drv_saadc_sample();
        idle_state_handle();
    }
}

My result are the following :

[00:00:02.452,636] <info> app: 90

[00:00:02.527,526] <info> app: 96

[00:00:02.577,453] <info> app: 97

[00:00:04.377,746] <info> app: 102

[00:00:04.452,636] <info> app: 89

[00:00:04.527,526] <info> app: 96

[00:00:04.577,453] <info> app: 98

[00:00:06.377,746] <info> app: 101

[00:00:06.452,636] <info> app: 90

[00:00:06.527,526] <info> app: 96

[00:00:06.577,453] <info> app: 96

And of course, the values are not changing if I changed the value of the potentiometer. I don't understand why is it not working...
Another issue that I had, is that the adc value are showing 3 by 3 with a delay but I've not implemented a delay, so I don't know why...

Thanks for your help !

Chris