I am trying to configure or set gain in SAADC example, for various gains it should operate but i am 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. Gain defined in nrfx.saadc.h file are default one but i want it to work as per user defined gain.
But i want to set to below mentioned Gain values
1, 2, 4, 5, 8, 10, 16, 32.
When i am changing gain values in below mentioned lines i am getting error.
Default Gain in nrf.saadc.h file are
NRF_SAADC_GAIN1_6 = SAADC_CH_CONFIG_GAIN_Gain1_6, ///< Gain factor 1/6.
NRF_SAADC_GAIN1_5 = SAADC_CH_CONFIG_GAIN_Gain1_5, ///< Gain factor 1/5.
NRF_SAADC_GAIN1_4 = SAADC_CH_CONFIG_GAIN_Gain1_4, ///< Gain factor 1/4.
NRF_SAADC_GAIN1_3 = SAADC_CH_CONFIG_GAIN_Gain1_3, ///< Gain factor 1/3.
NRF_SAADC_GAIN1_2 = SAADC_CH_CONFIG_GAIN_Gain1_2, ///< Gain factor 1/2.
NRF_SAADC_GAIN1 = SAADC_CH_CONFIG_GAIN_Gain1, ///< Gain factor 1.
NRF_SAADC_GAIN2 = SAADC_CH_CONFIG_GAIN_Gain2, ///< Gain factor 2.
NRF_SAADC_GAIN4 = SAADC_CH_CONFIG_GAIN_Gain4, ///< Gain factor 4.
Gain defined in nrfx.saadc.h file is
.gain = NRF_SAADC_GAIN1_4,
So how can i define gains and make it work properly. Im using only 1channel AIN0 with SDK15.3 nrf52832.
Presently its working properly with default gain values.
.
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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[2]; /**< 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;
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);
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();
}
}
/** @} */
This is the output what i am getting for default gain.
Please suggest.
