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SAADC with

I need to measure with SAADC two channels in the same time (NRF_SAADC_INPUT_AIN6 and NRF_SAADC_INPUT_AIN4).

Is possible ?

Have you an code example?

Thanks

Marco

  • Then ? how to set it ?. I don't understand.

    static nrf_saadc_value_t m_buffer_pool_scann[2][2]; This is NOT correct ?

    I use 2 channels. Could you tell me how ?

  • Sorry. I meant the SAMPLES_IN_BUFFER define should be N * the numbers of channels you use.

    I don't know what chip or SDK version you use, but this is written in SDK15.3.0, and tested with nRF52832:

    /**
     * Copyright (c) 2014 - 2019, Nordic Semiconductor ASA
     *
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without modification,
     * are permitted provided that the following conditions are met:
     *
     * 1. Redistributions of source code must retain the above copyright notice, this
     *    list of conditions and the following disclaimer.
     *
     * 2. Redistributions in binary form, except as embedded into a Nordic
     *    Semiconductor ASA integrated circuit in a product or a software update for
     *    such product, must reproduce the above copyright notice, this list of
     *    conditions and the following disclaimer in the documentation and/or other
     *    materials provided with the distribution.
     *
     * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
     *    contributors may be used to endorse or promote products derived from this
     *    software without specific prior written permission.
     *
     * 4. This software, with or without modification, must only be used with a
     *    Nordic Semiconductor ASA integrated circuit.
     *
     * 5. Any software provided in binary form under this license must not be reverse
     *    engineered, decompiled, modified and/or disassembled.
     *
     * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
     * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
     * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     */
    /** @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_log.h"
    #include "nrf_log_ctrl.h"
    #include "nrf_log_default_backends.h"
    
    #define SAMPLES_IN_BUFFER 2
    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 timer_handler(nrf_timer_event_t event_type, void * p_context)
    {
    
    }
    
    
    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);
    }
    
    
    void saadc_sampling_event_enable(void)
    {
        ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);
    
        APP_ERROR_CHECK(err_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);
    
            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++;
        }
    }
    
    
    void saadc_init(void)
    {
        ret_code_t err_code;
        nrf_saadc_channel_config_t channel_config0 =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
        nrf_saadc_channel_config_t channel_config1 =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);
    
        err_code = nrf_drv_saadc_init(NULL, saadc_callback);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_channel_init(0, &channel_config0);
        APP_ERROR_CHECK(err_code);
        err_code = nrf_drv_saadc_channel_init(1, &channel_config1);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
    
    }
    
    
    /**
     * @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();
    
        ret_code_t ret_code = nrf_pwr_mgmt_init();
        APP_ERROR_CHECK(ret_code);
    
        saadc_init();
        saadc_sampling_event_init();
        saadc_sampling_event_enable();
        NRF_LOG_INFO("SAADC HAL simple example started.");
    
        while (1)
        {
            nrf_pwr_mgmt_run();
            NRF_LOG_FLUSH();
        }
    }
    
    
    /** @} */
    

  • Thank, but your file is exatly same at my code.

    I ask a conversion each 1 mS but sometime the vale are swapped.

    Marco

  • Can you test this one?

    /**
     * Copyright (c) 2014 - 2019, Nordic Semiconductor ASA
     *
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without modification,
     * are permitted provided that the following conditions are met:
     *
     * 1. Redistributions of source code must retain the above copyright notice, this
     *    list of conditions and the following disclaimer.
     *
     * 2. Redistributions in binary form, except as embedded into a Nordic
     *    Semiconductor ASA integrated circuit in a product or a software update for
     *    such product, must reproduce the above copyright notice, this list of
     *    conditions and the following disclaimer in the documentation and/or other
     *    materials provided with the distribution.
     *
     * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
     *    contributors may be used to endorse or promote products derived from this
     *    software without specific prior written permission.
     *
     * 4. This software, with or without modification, must only be used with a
     *    Nordic Semiconductor ASA integrated circuit.
     *
     * 5. Any software provided in binary form under this license must not be reverse
     *    engineered, decompiled, modified and/or disassembled.
     *
     * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
     * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
     * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     */
    /** @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_log.h"
    #include "nrf_log_ctrl.h"
    #include "nrf_log_default_backends.h"
    
    #define SAMPLES_IN_BUFFER 2
    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 timer_handler(nrf_timer_event_t event_type, void * p_context)
    {
    
    }
    
    
    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, 1);
        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);
    }
    
    
    void saadc_sampling_event_enable(void)
    {
        ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);
    
        APP_ERROR_CHECK(err_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);
            
            if(m_adc_evt_counter%100 == 0)
            {
                int i;
                NRF_LOG_RAW_INFO("%d, ", (int)m_adc_evt_counter);
        
                for (i = 0; i < SAMPLES_IN_BUFFER; i++)
                {
                    NRF_LOG_RAW_INFO("%d,", p_event->data.done.p_buffer[i]);
                }
                
                NRF_LOG_RAW_INFO("\r\n");
            }
            m_adc_evt_counter++;
        }
    }
    
    
    void saadc_init(void)
    {
        ret_code_t err_code;
        nrf_saadc_channel_config_t channel_config0 =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
        nrf_saadc_channel_config_t channel_config1 =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);
    
        err_code = nrf_drv_saadc_init(NULL, saadc_callback);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_channel_init(0, &channel_config0);
        APP_ERROR_CHECK(err_code);
        err_code = nrf_drv_saadc_channel_init(1, &channel_config1);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
    
    }
    
    
    /**
     * @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();
    
        ret_code_t ret_code = nrf_pwr_mgmt_init();
        APP_ERROR_CHECK(ret_code);
    
        saadc_init();
        saadc_sampling_event_init();
        saadc_sampling_event_enable();
        NRF_LOG_INFO("SAADC HAL simple example started.");
    
        while (1)
        {
            nrf_pwr_mgmt_run();
            NRF_LOG_FLUSH();
        }
    }
    
    
    /** @} */
    

    I can't see that the values are swapped. Are they if you run the project with this main.c file?

    In your case, how do you determine that the values/channels are swapped?

  • No, is impossible for me now.

    static void lpcomp_event_handler(nrf_lpcomp_event_t event)
    {
      if (event == NRF_LPCOMP_EVENT_DOWN)
      {
          nrf_gpio_pin_set(PIN_P0_20_TP6);
              
          u_STATO10.STATO10_bit.mm_EOC = 0;
          nrf_drv_saadc_sample();
          while(!u_STATO10.STATO10_bit.mm_EOC);
    
          buff_I[puntIP]=adc_value_inex;
          buff_P[puntIP]=adc_value_pulse;
          puntIP++;
          if (puntIP>99)puntIP=0;
    
          nrf_gpio_pin_clear(PIN_P0_20_TP6);
    
        }
    }
    

    I working on my target and I don' start a conversion with a timer but when a pulse arrive on AIN5.

    I trigger this event with a LPCOMP event DOWN on AIN5.

    I have tested it with the PO_20 test point and this event is perfectly synchronized with the AIN5.

    I have discovered that if the time between 2 conversion is more then 10 mS the error do not appear

    Report--00038.pdf

    I have send you my situation.

    In the report the signal RED is connected to AIN5 in order to generate an event on LPCOMP

    In BLU one of the 2 signal that I need to measure with the SAADC

    In yellow the signal PO_20 (test point) this signal go up when the evend LPCOMP down arrive and go down after the conversion (see my code above).

    In the buffer buff_I and buff_P I store my conversion and sometime I read a zero value instead the correct value. see file in attach.

    Note that on the oscilloscope the signal BLU is always UP when the YELLOW signal arrive.

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