Im using nrf52832 kit with sdk15.3 SAADC example for ADC output, which is working fine but im not getting how to vary gain.
i want to set gain these values 1,2,4,5,8,10,16,32 . Im using only 1 channel channel0 (AIN0).
Is it possible to set more than one gain value to only 1 channel ?
please suggest
You will need to execute a new ADC measurement for each configuration, only 1 gain setting can be active at the time.
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.
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.
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.
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 ?
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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