Hi,
I'm trying to get SPI working with an accelerometer (LIS3DH). I'm currently trying to use the nrf_drv_spi_transfer() function. See code snippets below.
// Initialize SPI
nrf_drv_spi_config_t spiConfig = NRF_DRV_SPI_DEFAULT_CONFIG;
spiConfig.ss_pin = ACCEL_CS_PIN;
spiConfig.miso_pin = SPI_MISO_PIN;
spiConfig.mosi_pin = SPI_MOSI_PIN;
spiConfig.sck_pin = SPI_CLK_PIN;
spiConfig.mode = NRF_DRV_SPI_MODE_3;
spiConfig.bit_order = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST;
nrf_drv_spi_init(&spi, &spiConfig, spiEventHandler, NULL);
void spiEventHandler(nrf_drv_spi_evt_t const *p_event, void *p_context)
{
SEGGER_RTT_printf(0, "spiEventHandler: %d\n", spiReadData[0]);
spiReadData[0] = 0x00;
}
void getAccelData()
{
spiCommandData[0] = 0x8F;
nrf_drv_spi_transfer(&spi, spiCommandData, 1, spiReadData, 1);
}
When viewing the clock on an oscilloscope I see that there are only 8 clock pulses and it's sending the correct packet of TX info (0x8F). However, I don't see any further clock pulses for reading. Also, the data that I get in the spiReadData buffer becomes 0xFF when the event handler triggers.
If I set the length of the spiReadData to 2, then I see the correct 16 clock pulses and the second item in the buffer is the expected value.
Any advice? Am I using the function incorrectly? I'm assuming that a transfer of 1 length for TX means send the 8 bits in the TX buffer, and a read of 1 length means pulse an additional 8 clock pulses to read the data into the RX buffer.
Thanks.
