Hello,
I am developing a system with the nRF52832 and SPI peripherals. I have been trying unsuccessfully for a while to resolve a communication issue with one of the devices (Bosch BME280). The strange thing is that (1) when examined with a logic probe, the MOSI and MISO signals are both correct. Also, (2) communication with another SPI peripheral works great. (Currently, I am working with the problematic peripheral in isolation, although eventually I need them to both function at the same time.)
This is all on a custom PCB, but based on the above, I am pretty sure it must be a software issue.
Reading CHIP_ID repeatedly (peripheral correctly supplies the value 0x60):
However, the nRF52 incorrectly gets the value 0x00.
<info> app: BME280 Chip ID: 0
My setup for the SPI interface is as follows:
void bme_init_interface(void)
{
// Init SPI interface
nrf_gpio_cfg_output(BME_SS_PIN); // Make chip select an output
nrf_gpio_cfg_output(MOSI_PIN); // Make MOSI an output
nrf_gpio_cfg_input(MISO_PIN, NRF_GPIO_PIN_NOPULL); // Make MISO an input
nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.ss_pin = NRFX_SPI_PIN_NOT_USED; // NOTE: can try this but chip select toggled manually in BME SPI functions
spi_config.miso_pin = MISO_PIN;
spi_config.mosi_pin = MOSI_PIN;
spi_config.sck_pin = SCK_PIN;
spi_config.frequency = NRF_SPI_FREQ_250K; // NOTE: Low freq for testing
spi_config.mode = NRF_DRV_SPI_MODE_0; // SCK active high (resting low), sample on leading edge of clock. (BME should be compatible with modes 00 and 11)
spi_config.bit_order = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST; // MSB first according to timing diagrams in datasheet
spi_config.irq_priority = APP_IRQ_PRIORITY_HIGHEST; // highest priority level available to application (level 2, higher than default for SPI of 6)
APP_ERROR_CHECK(nrf_drv_spi_init(&spi_bme, &spi_config, spi_bme_event_handler, NULL));
// Lock BME into SPI mode
BME_CsClr(); // Do this before initializing AFE in order to lock BME in SPI mode without incidentally sending commands interpreted as I2C
nrf_delay_ms(3);
BME_CsSet();
nrf_delay_ms(10);
NRF_LOG_INFO("BME280 SPI initialized.");
}
I have triple-checked my pin assignments - MOSI on P0.00, SCLK on P0.01, MISO on P0.06, and !CS on P0.07.
// SPI pins
#define SCK_PIN 1 // SPI clock GPIO pin number.
#define MOSI_PIN 0 // SPI Master Out Slave In GPIO pin number.
#define MISO_PIN 6 // SPI Master In Slave Out GPIO pin number.
// SPI master - BME280 sensor
#define BME_SS_PIN 7 // SPI Slave Select GPIO pin number.
#define BME_SPI_INSTANCE 1 /**< SPI instance index. */
Do the experts have any ideas on what may be going wrong? Thanks in advance.
