nrf52- SPI read/MISO with bit offset

RE: nrf52- SPI read/MISO with bit offset

hmolesworth — Thu, 29 Aug 2024 22:18:05 GMT

If not doing so, set /CS, SCK and MOSI to high-drive H0H1 after any default port pin settings. Easier to see issues if 'scope with SPI frequency set to 8MHz.

Think the ICM-42670-P uses Mode 2 and soggy clock and wrong mode setting may also be an issue; worth trying both H0H1 and Mode 2.

RE: nrf52- SPI read/MISO with bit offset

Ron — Thu, 29 Aug 2024 21:40:05 GMT

Thanks for the quick reply,

I omitted those definitions, I used mode 0, this is what I have done

    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.sck_pin  = PIN_SPI_SCK;
    spi_config.miso_pin = PIN_SPI_MISO;
    spi_config.mosi_pin = PIN_SPI_MOSI;
    spi_config.ss_pin   = PIN_SPI_IMU_CS;
	spi_config.mode   	= NRF_DRV_SPI_MODE_0;
    err_code = nrf_drv_spi_init(&spi, &spi_config, NULL, NULL);

Trying mode 3 I get no response at all from the device,

it is ICM-42670-P

https://invensense.tdk.com/products/motion-tracking/6-axis/icm-42670-p/

Any ideas?

RE: nrf52- SPI read/MISO with bit offset

hmolesworth — Thu, 29 Aug 2024 19:37:46 GMT

Slightly confusing, settings vs 'scope image. Suggest changing the SPI Mode to 0 or 3 and see if that works as it doesn't look like Mode 0 is actually being used especially as pins are all set to NRF_DRV_SPI_PIN_NOT_USED; MISO data is maybe being sampled on the rising edge of the clock with the settings you have, and from the display it shows data should be sampled on the falling edge of the clock.

Try
    .mode         = NRF_DRV_SPI_MODE_0,                      \
or
    .mode         = NRF_DRV_SPI_MODE_3,                      \