RE: How to vary gain in SAADC example nrf52832 SDK15.3 ?

Pooja Vernekar — Fri, 12 Jul 2019 08:46:22 GMT

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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 "app_timer.h"


#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
//-------------------------spi code---------------------------
#include "nrf_drv_spi.h"
#include "nrf_gpio.h"


#define SPI_INSTANCE  1 /**< SPI instance index. */
static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
static volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. */

//#define TEST_STRING "Nordic"
static uint8_t       m_tx_buf[00100000];           /**< TX buffer. */
static uint8_t       m_rx_buf[40];    /**< RX buffer. */
//static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */


/**
 * @brief SPI user event handler.
 * @param event
 */
void spi_event_handler(nrf_drv_spi_evt_t const * p_event)
{
   spi_xfer_done = true;
	
		NRF_LOG_INFO(" Sent %d bytes: ", p_event->data.done.tx_length);
		for(int i=0; i< p_event->data.done.tx_length;i++)
		{
				NRF_LOG_INFO(" ;(0x%x); ",p_event->data.done.p_tx_buffer[i], p_event->data.done.p_tx_buffer[i]);
		}
		//NRF_LOG_INFO("\r\n");
		NRF_LOG_INFO(" Received %d bytes: ", p_event->data.done.rx_length);
		 for(int i=0; i< p_event->data.done.rx_length;i++)
		{
				NRF_LOG_INFO(" ;(0x%x); ",p_event->data.done.p_rx_buffer[i], p_event->data.done.p_rx_buffer[i]);
				nrf_delay_ms(5);
		}
		//NRF_LOG_INFO("\r\n\n");
}


void spi_con(void)
{
	
 nrf_gpio_cfg_output(18); //Configure pin 18 as output

 NRF_CLOCK->TASKS_HFCLKSTART = 1; //Start high frequency clock
 while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
 {
      //Wait for HFCLK to start
 }
 NRF_CLOCK->EVENTS_HFCLKSTARTED = 0; //Clear event
 
 
 //Configure GPIOTE to toggle pin 18 
 NRF_GPIOTE->CONFIG[0] = GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos |
                         GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos |
                         18 << GPIOTE_CONFIG_PSEL_Pos | 
                         GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos;
 
 //Configure timer
 NRF_TIMER1->PRESCALER = 3;
 NRF_TIMER1->CC[0] = 1;  // Adjust the output frequency by adjusting the CC.
 NRF_TIMER1->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos;
 NRF_TIMER1->TASKS_START = 1;
 
 //Configure PPI
 NRF_PPI->CH[0].EEP = (uint32_t) &NRF_TIMER1->EVENTS_COMPARE[0];
 NRF_PPI->CH[0].TEP = (uint32_t) &NRF_GPIOTE->TASKS_OUT[0];
 
 NRF_PPI->CHENSET = PPI_CHENSET_CH0_Enabled << PPI_CHENSET_CH0_Pos;
	
    LEDS_CONFIGURE(BSP_LED_0_MASK);
    LEDS_OFF(BSP_LED_0_MASK);
	
	
	
		nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.ss_pin   = SPI_SS_PIN;
    spi_config.miso_pin = SPI_MISO_PIN;
    spi_config.mosi_pin = SPI_MOSI_PIN;
    spi_config.sck_pin  = SPI_SCK_PIN;
    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));

    NRF_LOG_INFO("SPI example started.");


        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, 40);
        spi_xfer_done = false;

			  m_tx_buf[0]=0x0d;
			
			
        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, 2, m_rx_buf, 40));
	
	
	
        while (!spi_xfer_done)
        {
            __WFE();
        }
	
			
}

#define SAMPLES_IN_BUFFER 20
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;
int GAIN=0;

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, 100);
    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_config =
     NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
    switch(GAIN)
		{
			case 1:
				nrf_drv_saadc_channel_uninit(NRF_SAADC_GAIN1);
			case 2:
			 nrf_drv_saadc_channel_uninit (NRF_SAADC_GAIN2);
			case 3:
				nrf_drv_saadc_channel_uninit(NRF_SAADC_GAIN4);
			default:
				NRF_LOG_INFO("no operation");	
		}
    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_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);

		spi_con();
    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();
    }
}


/** @} */

Hello Kenneth,

I have attached code please verify the code and give feedback what changes to be made if required.

As channel 0 consists of AIN0-AIN7 so i want each of AIN pins to get configured with each gain. I have added switch case but im not sure with code what i did. I want t use each gain defined in header file.

Please suggest

RE: How to vary gain in SAADC example nrf52832 SDK15.3 ?

Pooja Vernekar — Fri, 12 Jul 2019 05:22:54 GMT

but if i define gain in nrf.saadc.h then it gives error.

it works fine for default gain, but i want to set gain with different values. How can i do that ?

RE: How to vary gain in SAADC example nrf52832 SDK15.3 ?

Kenneth — Thu, 11 Jul 2019 16:59:02 GMT

If you base your code on \examples\peripheral\saadc\ I believe this should be straight forward. Simply call nrf_drv_saadc_channel_init(), nrf_drv_saadc_buffer_convert(), and nrf_drv_saadc_channel_uninit() for each gain setting you want to sample.

RE: How to vary gain in SAADC example nrf52832 SDK15.3 ?

Pooja Vernekar — Thu, 11 Jul 2019 11:05:03 GMT

Hello Kenneth,

Im trying to configure or set gain in SAADC example, for various gains it should operate but im not getting how to set gain register so that i get SAADC output depending on various gain and even i tried to change gain values in nrfx.saadc.h file but getting error. gains defined in nrfx.saadc.h files are default one but i want it to work as per my amplifier. So how can i define gains and make it work properly. Im using only 1channel AIN0

Presently its working properly with default gain values.

Please Suggest.

RE: How to vary gain in SAADC example nrf52832 SDK15.3 ?

Kenneth — Mon, 08 Jul 2019 12:14:28 GMT

You will need to execute a new ADC measurement for each configuration, only 1 gain setting can be active at the time.