SPIM RX started by ppi delay about 6us

[xjhu]

HI all,I am looking for a help.how to start SPIM RX task immediately delay less than 2us？

I have a SPIM test on 52832 DK board(QFAAE0) with SDK16.0, the MISO pin has connected with a GPIOTE pin together,when GPIOTE HITOLO event happened,ppi will trigger SPIM START task,but the bytes received are not correct,because the rx started with 6us delay, in the scope picture the yellow wave is MISO and the blue wave is SCK.I have tested nrf_drv_clock_hfclk_request and sd_power_mode_set(NRF_POWER_MODE_CONSTLAT),but there was not a noticable effect.

my test code are here:

static uint32_t nnn = 0;
nnn = sd_power_mode_set(NRF_POWER_MODE_CONSTLAT);

nrf_drv_gpiote_init();
nrf_drv_gpiote_in_config_t cfg = NRFX_GPIOTE_CONFIG_IN_SENSE_HITOLO(true);
nrfx_err_t err_code = nrf_drv_gpiote_in_init(PIN_SPI_RXD, &cfg, spim_gpiote_event_handler);
APP_ERROR_CHECK(err_code);
nrf_drv_gpiote_in_event_enable(PIN_SPI_RXD, true);

nrfx_spim_config_t spi_config = NRFX_SPIM_DEFAULT_CONFIG;
spi_config.mode = NRF_SPIM_MODE_0;
spi_config.frequency = NRF_SPIM_FREQ_500K;
spi_config.ss_pin = NRFX_SPIM_PIN_NOT_USED;
spi_config.miso_pin = PIN_SPI_RX;
spi_config.mosi_pin = NRFX_SPIM_PIN_NOT_USED;//PIN_SPI_TX;
spi_config.sck_pin = PIN_SPI_SCK;
APP_ERROR_CHECK(nrfx_spim_init(&spim, &spi_config, spim_event_handler, NULL));
nrf_gpio_cfg(
PIN_SPI_RX,
NRF_GPIO_PIN_DIR_INPUT,
NRF_GPIO_PIN_INPUT_CONNECT,
NRF_GPIO_PIN_PULLUP,
NRF_GPIO_PIN_H0H1,
NRF_GPIO_PIN_NOSENSE);

spi_xfer_done = false;
nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TRX(NULL, 0, m_rx_buf, sizeof(m_rx_buf));
APP_ERROR_CHECK(nrfx_spim_xfer(&spim, &xfer_desc, 0));//NRFX_SPIM_FLAG_HOLD_XFER));//
nrf_spim_task_trigger(spim.p_reg, NRF_SPIM_TASK_SUSPEND);
spim_ppi_channel_init();

static bool spim_ppi_channel_init(void)

{

NRF_SPIM_Type * p_spim = (NRF_SPIM_Type *)spim.p_reg;
nrf_ppi_channel_include_in_group(SPIM_RX_START_PPI_CHANNEL, SPIM_RX_GROUP_PPI_CHANNEL);
nrf_ppi_channel_and_fork_endpoint_setup(SPIM_RX_START_PPI_CHANNEL,
nrf_drv_gpiote_in_event_addr_get(PIN_SPI_RXD),
nrf_spim_task_address_get(p_spim, NRF_SPIM_TASK_RESUME),//NRF_SPIM_TASK_START),
(uint32_t)nrf_ppi_task_group_disable_address_get(SPIM_RX_GROUP_PPI_CHANNEL));
nrf_ppi_group_enable(SPIM_RX_GROUP_PPI_CHANNEL);

}

void spim_event_handler(nrfx_spim_evt_t const * p_event,
void * p_context)
{
spi_xfer_done = true;
NRF_LOG_INFO("Transfer completed.");
if (m_rx_buf[0] != 0)
{
NRF_LOG_INFO(" Received:");
NRF_LOG_HEXDUMP_INFO(m_rx_buf, 16);
}
nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TRX(NULL, 0, m_rx_buf, sizeof(m_rx_buf));
APP_ERROR_CHECK(nrfx_spim_xfer(&spim, &xfer_desc, 0));//NRFX_SPIM_FLAG_HOLD_XFER));
nrf_spim_task_trigger(spim.p_reg, NRF_SPIM_TASK_SUSPEND);
// nrf_ppi_group_enable(SPIM_TX_STOP_GROUP_PPI_CHANNEL);
nrf_ppi_group_enable(SPIM_RX_GROUP_PPI_CHANNEL);
}

[Håkon Alseth]

Hi,

 

I setup a quick test related to your description, and I see a delay of approx. 1 us:

 

Here's my test source (based on peripherals/spi/ example in SDK 17):

/**
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 *
 * 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
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 *    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.
 *
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 * 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.
 *
 */
#include "nrf_drv_spi.h"
#include "app_util_platform.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "boards.h"
#include "app_error.h"
#include <string.h>
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_drv_gpiote.h"
#include "nrf_ppi.h"

#define SPI_INSTANCE  0 /**< 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 test long string for testing"
static uint8_t       m_tx_buf[] = TEST_STRING;           /**< TX buffer. */
static uint8_t       m_rx_buf[sizeof(TEST_STRING) + 1];    /**< 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,
                       void *                    p_context)
{
    spi_xfer_done = true;
    NRF_LOG_INFO("Transfer completed.");
    if (m_rx_buf[0] != 0)
    {
        NRF_LOG_INFO(" Received:");
        NRF_LOG_HEXDUMP_INFO(m_rx_buf, strlen((const char *)m_rx_buf));
    }
}

void ppi_setup(void)
{

    NRF_PPI->CH[0].EEP = (uint32_t) nrf_drv_gpiote_in_event_addr_get(SPI_MISO_PIN);
    NRF_PPI->CH[0].TEP = (uint32_t)(NRF_SPIM_Type *)&((spi.u.spim.p_reg)->TASKS_RESUME);
    NRF_PPI->CHENSET = PPI_CHENSET_CH0_Enabled << PPI_CHENSET_CH0_Pos;
}

int main(void)
{
    bsp_board_init(BSP_INIT_LEDS);

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    nrf_drv_gpiote_init();

    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_drv_gpiote_in_config_t cfg = NRFX_GPIOTE_CONFIG_IN_SENSE_HITOLO(true);
    cfg.pull = NRF_GPIO_PIN_PULLUP;
    nrfx_err_t err_code = nrf_drv_gpiote_in_init(SPI_MISO_PIN, &cfg, NULL);
    APP_ERROR_CHECK(err_code);
    nrf_drv_gpiote_in_event_enable(SPI_MISO_PIN, true);

    NRF_LOG_INFO("SPI example started.");
    ppi_setup();
    NRF_LOG_FLUSH();
    while (1)
    {
        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, m_length);
        spi_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));
        nrf_spim_task_trigger(spi.u.spim.p_reg, NRF_SPIM_TASK_SUSPEND);
        while (!spi_xfer_done)
        {
            __WFE();
        }        

        bsp_board_led_invert(BSP_BOARD_LED_0);
        nrf_delay_ms(200);
    }
}

 

Since I do not have your full example, I'm not able to test the exact same setup as you, but the above seems to work as intended.

 

Kind regards,

Håkon

[xjhu]

HI Håkon Alseth，thanks your reply.

my code is tested under enable softdevice(S132-7.0.1) and setup ble functions.

I called idle_state_handle() in main loop.

static void idle_state_handle(void)
{
ret_code_t err_code;

err_code = nrf_ble_lesc_request_handler();
APP_ERROR_CHECK(err_code);

if (NRF_LOG_PROCESS() == false)
{
nrf_pwr_mgmt_run();
}
}

I will test your code and report the result.