saadc blocking issue

[ericalbers]

I can run the SAADC example and read the analog inputs fine, now I've modified the code to simply read the adc with the blocking nrf_drv_saadc_sample_convert call

All I get back is 0's on the read....using the same input AIN1 in the example program with a callback works and shows values?

One thing I note, if I change the config to have a acquisition time of 3us it reads values...but anything higher (like the default 40us) it reads 0?

in Main I do these steps:

 nrf_saadc_channel_config_t cfg =  NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);

 nrf_drv_saadc_channel_init(NRF_SAADC_INPUT_AIN1,&cfg);

while(1)

{

 nrf_pwr_mgmt_run();

 retval = nrf_drv_saadc_sample_convert(NRF_SAADC_INPUT_AIN1,&myval);
 if (retval == NRF_SUCCESS)
{   
    NRF_LOG_INFO("TESTING ch1=%d ",myval);
}

NRF_LOG_FLUSH();

}

[Håkon Alseth]

Hi,

 

I tried to cut down the saadc example in the SDK to run as you've done, and it seems to work as intended at my end.

My pin is floating, and therefore prints ADC values between 0 and 800, but when grounding or pulling the pin to VDD, I see ~0 (GND) and ~800 (VDD)

Attached is my example program.

Best regards,

Håkon

Fullscreen main.c Download

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/** @file
 * @defgroup nrf_adc_example main.c
 * @{
 * @ingroup nrf_adc_example
 * @brief ADC Example Application main file.
 *
 * This file contains the source code for a sample application using ADC.
 *
 * @image html example_board_setup_a.jpg "Use board setup A for this example."
 */

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nrf.h"
#include "nrf_drv_saadc.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_timer.h"
#include "boards.h"
#include "app_error.h"
#include "nrf_delay.h"
#include "app_util_platform.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_drv_power.h"


#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#define SAMPLES_IN_BUFFER 5
volatile uint8_t state = 1;

static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(0);
static nrf_saadc_value_t     m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t     m_ppi_channel;
static uint32_t              m_adc_evt_counter;


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", (int)m_adc_evt_counter);

        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
            NRF_LOG_INFO("%d", p_event->data.done.p_buffer[i]);
        }
        m_adc_evt_counter++;
    }
    NRF_LOG_INFO("ADC ISR");
}


/**
 * @brief Function for main application entry.
 */
int main(void)
{
    uint32_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();

    err_code = nrf_drv_power_init(NULL);
    APP_ERROR_CHECK(err_code);

    ret_code_t ret_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(ret_code);

    NRF_LOG_INFO("SAADC HAL simple example.");
    err_code = nrf_drv_saadc_init(NULL, saadc_callback);
    APP_ERROR_CHECK(err_code);
    nrf_saadc_channel_config_t cfg =  NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);
    cfg.acq_time = NRF_SAADC_ACQTIME_40US;

    nrf_drv_saadc_channel_init(NRF_SAADC_INPUT_AIN1,&cfg);

    while (1)
    {
        nrf_pwr_mgmt_run();
        static nrf_saadc_value_t myval;
        err_code = nrf_drv_saadc_sample_convert(NRF_SAADC_INPUT_AIN1,&myval);
        if (err_code == NRF_SUCCESS)
        {   
            NRF_LOG_INFO("TESTING ch1=%d ",myval);
        }
        nrf_delay_ms(100);
        NRF_LOG_FLUSH();
        
    }
}


/** @} */

[ericalbers]

Thank you, oddly, I paste your code in and it works....and bringing my code back also now works....yet I have changed no code....I think the problem must be between keyboard and screen :-)

Thanks!