Dear support team, we are trying to make the device ST IIS2DLPC (accelormeter) talk via SPI to the dev board PCA10040
We are using the evaluation board STEVAL-MKI191V1 wich hosts the device and expose the pins easily as shown below:
As first attempt we would like to retrieve the "Who I Am" code of the device(read register 0x8F). So we changed the code of the example "SPI" as shown below.
As you can see we changed the PINS to reflect the real connections. We received somethin on terminal containing somehow the 0x44 number.
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#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"
#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. */
static uint8_t m_tx_buf[] = {0x8F,0x8F}; /**< TX buffer. */
volatile uint8_t m_rx_buf[] = {0x00,0x00}; /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf); /**< Transfer length. */
/**2
* @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));
}
}
int main(void)
{
bsp_board_init(BSP_INIT_LEDS);
APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();
nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.ss_pin = 29;
spi_config.miso_pin = 28;
spi_config.mosi_pin = 4;
spi_config.sck_pin = 3;
spi_config.mode = NRF_DRV_SPI_MODE_3;
spi_config.frequency=SPI_FREQUENCY_FREQUENCY_M1;
spi_config.bit_order = NRF_SPI_BIT_ORDER_MSB_FIRST;
APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
NRF_LOG_INFO("SPI example started.");
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));
//APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, 2, m_rx_buf, 2));
while (!spi_xfer_done)
{
__WFE();
}
NRF_LOG_FLUSH();
bsp_board_led_invert(BSP_BOARD_LED_0);
nrf_delay_ms(1000);
}
}
How come it is not repeted in the loop?
Why it show more than two bytes?
Below find how signals look on the scope. Everything seems ok:
(from top: MISO, MOSI, CLK, SS)
Device specs: https://www.st.com/en/mems-and-sensors/iis2dlpc.html
SPI bus interface at page 41
thank you in advance,
A.
