nRF52832 SAADC and BLE

Question

Hello, 
 I'm using following code to read two channels of SAADC. It works fine when device is not connected to BLE central device. As soon as it's connected, the saadc_callback function stops executing despite the fact that nrf_drv_saadc_sample(); returns NRF_SUCCESS. In the log, I can see that saadc_callback() being called when device is not connected to BLE and no saadc_callback() when device connected to BLE. 
 One thing more, the saadc_callback() gets being called from a timer in the main() (although with incorrect values) function but not being called when saadc_voltage_get() is used other than main(). 
 I have tried changing the priority of SAADC IRQ in the sdk_config.h from 7 to 3, still no success. The code otherwise works fine and at device startup, when it's not connected, SAADC reads values. 
 The code is here: 
 #include "nrf_drv_saadc.h"
#include "nrf_log.h" 
#include "nrf_log_ctrl.h"
#include "nrf_delay.h"

#include "adc_driver.h"

#define SAMPLES_IN_BUFFER 2

static nrf_saadc_value_t m_buffer[2][SAMPLES_IN_BUFFER];
uint16_t drive_V, batt_V;

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
 NRF_LOG_INFO("SAADC event: %d", p_event->type);

 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);

 drive_V = p_event->data.done.p_buffer[0];
 batt_V = p_event->data.done.p_buffer[1];
 
 NRF_LOG_INFO("Drive voltage=%d", drive_V);
 //NRF_LOG_INFO("Sys volatge=%d", batt_V);

 }
}

void saadc_init(void)
{
 ret_code_t err_code;

 nrf_saadc_channel_config_t channel_config_1 
 = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);
 nrf_saadc_channel_config_t channel_config_2 
 = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);

 err_code = nrf_drv_saadc_init(NULL, saadc_callback);
 APP_ERROR_CHECK(err_code);

 err_code = nrf_drv_saadc_channel_init(1, &channel_config_1);
 APP_ERROR_CHECK(err_code);
 err_code = nrf_drv_saadc_channel_init(2, &channel_config_2);
 APP_ERROR_CHECK(err_code);

 err_code = nrf_drv_saadc_buffer_convert(m_buffer[0], SAMPLES_IN_BUFFER);
 APP_ERROR_CHECK(err_code);
 err_code = nrf_drv_saadc_buffer_convert(m_buffer[1], SAMPLES_IN_BUFFER);
 APP_ERROR_CHECK(err_code);

 
 // get values
 saadc_voltage_get();


 // Analog PIN assignments
 // P0.02/AIN0
 // P0.03/AIN1 --> Drive_V
 // P0.04/AIN2 --> Batt_V
}

void saadc_voltage_get(){
 ret_code_t err_code;

 err_code = nrf_drv_saadc_sample();
 if (err_code == NRF_SUCCESS){
 NRF_LOG_INFO("SAADC getting voltage...");
 }
 else{
 NRF_LOG_INFO("SAADC sampling issue.");
 }
 
 nrf_delay_ms(2);
}

void saadc_voltage_get_drive(uint16_t *voltage){
 saadc_voltage_get();
 *voltage = drive_V;
}

void saadc_voltage_get_battery(uint16_t *voltage){
 saadc_voltage_get();
 *voltage = batt_V;
}