By changing ss_duration the duration CSN is high doesn't seem to be effected?
ss_duration = 2
CSN
SCK
ss_duration = 64
CSN
SCK
Setup
SPI Config
#define SS_DURATION_SHORT 2
#define SS_DURATION_LONG 64
nrfx_spim_config_t spi_config = NRFX_SPIM_DEFAULT_CONFIG;
spi_config.ss_pin = DEVICE_CS;
spi_config.miso_pin = SPI_MISO;
spi_config.mosi_pin = NRFX_SPIM_PIN_NOT_USED;
spi_config.sck_pin = SPI_SCK;
spi_config.ss_active_high = false;
spi_config.frequency = NRF_SPIM_FREQ_1M;
spi_config.mode = NRF_SPIM_MODE_0;
spi_config.bit_order = NRF_SPIM_BIT_ORDER_MSB_FIRST;
spi_config.dcx_pin = NRFX_SPIM_PIN_NOT_USED;
spi_config.use_hw_ss = true;
spi_config.ss_duration = SS_DURATION_SHORT;
nrfx_spim_init(&spi, &spi_config, NULL, NULL);
spi.p_reg->RXD.PTR = (uint32_t)sample_buffer;
spi.p_reg->RXD.MAXCNT = sizeof(sample_buffer[0]); //Size of transaction
spi.p_reg->RXD.LIST = 1; //Use ARRAY List
PPI
SPIM3 END EVENT -> SPIM3 START TASK
SPIM3 END EVENT -> TIMER2 COUNT TASK
Example Code Below
/**
* Copyright (c) 2014 - 2020, 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 blinky_example_main main.c
* @{
* @ingroup blinky_example
* @brief Blinky Example Application main file.
*
* This file contains the source code for a sample application to blink LEDs.
*
*/
#include <stdbool.h>
#include <stdint.h>
#include "nrf_delay.h"
//Nordic
#include "nrf_gpio.h"
#include "nrfx_spim.h"
#include "nrfx_timer.h"
#include "nrfx_ppi.h"
#include "nrf_drv_ppi.h"
#define SAMPLES 1001
#define SAMPLE_BUFFER_SIZE SAMPLES + 100
static uint8_t sample_buffer[SAMPLE_BUFFER_SIZE][3];
static volatile uint32_t sample_buffer_count = 0;
static const nrfx_spim_t spi = NRFX_SPIM_INSTANCE(3);
static const nrfx_timer_t count_timer = NRFX_TIMER_INSTANCE(2);
static nrf_ppi_channel_t spi_start_ppi_channel;
static nrf_ppi_channel_t spi_sample_ppi_channel;
static nrf_ppi_channel_t spi_count_ppi_channel;
#define DEVICE_CS NRF_GPIO_PIN_MAP(1,10)
#define SPI_MISO NRF_GPIO_PIN_MAP(1,11)
#define SPI_SCK NRF_GPIO_PIN_MAP(0,28)
#define SS_DURATION_SHORT 2
#define SS_DURATION_LONG 64
static void start() {
//Enable sample looping channel
nrf_drv_ppi_channel_enable(spi_sample_ppi_channel);
//Reset pointer
spi.p_reg->RXD.PTR = (uint32_t)sample_buffer;
nrf_spim_task_trigger(spi.p_reg, NRF_SPIM_TASK_START);
}
static void timer_handler(nrf_timer_event_t event_type, void * p_context) {
}
static volatile uint32_t sample_buffer_count;
/**
* @brief Function for application main entry.
*/
int main(void)
{
nrf_gpio_cfg_output(DEVICE_CS);
nrf_gpio_cfg_output(SPI_SCK);
nrf_gpio_cfg_input(SPI_MISO, NRF_GPIO_PIN_NOPULL);
nrfx_spim_config_t spi_config = NRFX_SPIM_DEFAULT_CONFIG;
spi_config.ss_pin = DEVICE_CS;
spi_config.miso_pin = SPI_MISO;
spi_config.mosi_pin = NRFX_SPIM_PIN_NOT_USED;
spi_config.sck_pin = SPI_SCK;
spi_config.ss_active_high = false;
spi_config.frequency = NRF_SPIM_FREQ_1M;
spi_config.mode = NRF_SPIM_MODE_0;
spi_config.bit_order = NRF_SPIM_BIT_ORDER_MSB_FIRST;
spi_config.dcx_pin = NRFX_SPIM_PIN_NOT_USED;
spi_config.use_hw_ss = true;
spi_config.ss_duration = SS_DURATION_LONG;
nrfx_spim_init(&spi, &spi_config, NULL, NULL);
spi.p_reg->RXD.PTR = (uint32_t)sample_buffer;
spi.p_reg->RXD.MAXCNT = sizeof(sample_buffer[0]); //Size of transaction
spi.p_reg->RXD.LIST = 1; //Use ARRAY List
uint32_t err_code = nrf_drv_ppi_init();
//Sample
err_code = nrf_drv_ppi_channel_alloc(&spi_sample_ppi_channel);
APP_ERROR_CHECK(err_code);
uint32_t spi_end_evt_addr = nrfx_spim_end_event_get(&spi);
uint32_t spi_start_task_addr = nrfx_spim_start_task_get(&spi);
//Trigger SPI start on a SPI end
err_code = nrf_drv_ppi_channel_assign(spi_sample_ppi_channel, spi_end_evt_addr, spi_start_task_addr);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_ppi_channel_enable(spi_sample_ppi_channel);
APP_ERROR_CHECK(err_code);
//Count
//Setup timer in counter mode
nrfx_timer_config_t timer_cfg = NRFX_TIMER_DEFAULT_CONFIG;
timer_cfg.frequency = NRF_TIMER_FREQ_16MHz;
timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;
timer_cfg.mode = NRF_TIMER_MODE_LOW_POWER_COUNTER;
err_code = nrfx_timer_init(&count_timer, &timer_cfg, timer_handler);
//Count PPI
err_code = nrf_drv_ppi_channel_alloc(&spi_count_ppi_channel);
APP_ERROR_CHECK(err_code);
uint32_t timer_count_evt_addr = nrfx_timer_task_address_get(&count_timer, NRF_TIMER_TASK_COUNT);
err_code = nrf_drv_ppi_channel_assign(spi_count_ppi_channel, spi_end_evt_addr, timer_count_evt_addr);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_ppi_channel_enable(spi_count_ppi_channel);
APP_ERROR_CHECK(err_code);
//Start Sampling
start();
while(true) {
nrfx_timer_capture(&count_timer, NRF_TIMER_CC_CHANNEL1);
sample_buffer_count = nrfx_timer_capture_get(&count_timer, NRF_TIMER_CC_CHANNEL1);
if(sample_buffer_count >= SAMPLES) {
//Stop SPI
nrf_drv_ppi_channel_disable(spi_sample_ppi_channel);
//Reset counter timer
nrfx_timer_clear(&count_timer);
nrf_delay_ms(100);
//Start Again
start();
}
}
}
/**
*@}
**/
Regards,
Jonathan
