Why channel corresponding to the array is changed？

[creator]

#define SAMPLES_IN_BUFFER 4
static nrf_saadc_value_t     m_buffer_pool[1][SAMPLES_IN_BUFFER];

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);

        int i;
        NRF_LOG_INFO("ADC event number: %d\r\n", (int)m_adc_evt_counter);

        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
            NRF_LOG_INFO("%d\r\n", p_event->data.done.p_buffer[i]);
        }
        m_adc_evt_counter++;
    }
}
void saadc_init(void)
{

	 ret_code_t err_code;
	
    nrf_drv_saadc_config_t saadc_config = NRF_DRV_SAADC_DEFAULT_CONFIG;

	
    nrf_saadc_channel_config_t channel_0_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);

	
    nrf_saadc_channel_config_t channel_1_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);

	
    nrf_saadc_channel_config_t channel_2_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN6);

	
    nrf_saadc_channel_config_t channel_3_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN7);
			
	
    err_code = nrf_drv_saadc_init(&saadc_config, saadc_callback);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_channel_init(0, &channel_0_config);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(1, &channel_1_config);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(2, &channel_2_config);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(3, &channel_3_config);
    APP_ERROR_CHECK(err_code);	

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0],SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);   

	
	
}

[Jørgen Holmefjord]

When are the samples shifted? Are you using BLE in your application? What is the sample rate, and how do you trigger sampling? First thing you should try is to move the setup of the buffer in the callback, until after you read the buffer:

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;

        int i;
        NRF_LOG_INFO("ADC event number: %d\r\n", (int)m_adc_evt_counter);

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

[creator]

1.Don't use the BLE

2.E:\nordic\nRF5_SDK_12.2.0_f012efa\examples\peripheral\saadc

void saadc_sampling_event_init(void)
{
    ret_code_t err_code;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;
    err_code = nrf_drv_timer_init(&m_timer, &timer_cfg, timer_handler);
    APP_ERROR_CHECK(err_code);

    /* setup m_timer for compare event every 400ms */
    uint32_t ticks = nrf_drv_timer_ms_to_ticks(&m_timer, 400);
    nrf_drv_timer_extended_compare(&m_timer,
                                   NRF_TIMER_CC_CHANNEL0,
                                   ticks,
                                   NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
                                   false);
    nrf_drv_timer_enable(&m_timer);

    uint32_t timer_compare_event_addr = nrf_drv_timer_compare_event_address_get(&m_timer,
                                                                                NRF_TIMER_CC_CHANNEL0);
    uint32_t saadc_sample_task_addr   = nrf_drv_saadc_sample_task_get();

    /* setup ppi channel so that timer compare event is triggering sample task in SAADC */
    err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_assign(m_ppi_channel,
                                          timer_compare_event_addr,
                                          saadc_sample_task_addr);
    APP_ERROR_CHECK(err_code);
}

4.Tried you provide the callback processing, or not

[Jørgen Holmefjord]

I don't understand your last comment. Did you try the change I suggested in my answer above?