BMI270 initialization issue with STM32

Hi,

I'm working with the BMI270 with STM32F072 over SPI. I'm using the Gihub driver and I have problems with the initialization of the devide.
Debugging the code I noticed that the initialization fails when reading for the config files back after writing.

The error I get is always `BMI2_E_CONFIG_LOAD`.

Following my initialization code:

// Enable spi interface
	bmi270_dev.read = bm_spi_read;
	bmi270_dev.write = bm_spi_write;
	bmi270_dev.delay_us = delayUs;
	bmi270_dev.read_write_len = SPI_BUFF_SZ;
	bmi270_dev.intf = BMI2_SPI_INTERFACE;
	bmi270_dev.dev_id = 0;
	bmi270_dev.dummy_byte = 1;

	bmi270_dev.config_file_ptr = NULL; // Load the default `bmi270_config_file` hard coded in the driver

	// Initialize bmi270
	rslt = bmi270_init(&bmi270_dev);
	if (rslt != BMI2_OK)
		return rslt;

where:

int8_t bm_spi_read(uint8_t dev_addr, uint8_t reg_addr, uint8_t* data, uint16_t len) {
	UNUSED(dev_addr);

	if( len > SPI_BUFF_SZ ) {
		Error_Handler();
	}

	uint8_t rxarr[SPI_BUFF_SZ] = { reg_addr };
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_RESET);
	HAL_StatusTypeDef status = HAL_SPI_TransmitReceive(hspi_bmi, rxarr, rxarr,
			len + 1,
			COMM_DELAY);
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_SET);
	memcpy(data, rxarr + 1, len);
	return (status == HAL_OK ? BMI2_OK : BMI2_E_COM_FAIL);
}

int8_t bm_spi_write(uint8_t dev_addr, uint8_t reg_addr, const uint8_t *data, uint16_t len) {
	UNUSED(dev_addr);

	if( len > SPI_BUFF_SZ ) {
		Error_Handler();
	}

	uint8_t txarr[SPI_BUFF_SZ] = { reg_addr };
	memcpy(txarr + 1, data, len);
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_RESET);
	HAL_StatusTypeDef status = HAL_SPI_Transmit(hspi_bmi, txarr, len + 1,
			COMM_DELAY);
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_SET);
	return (status == HAL_OK ? BMI2_OK : BMI2_E_COM_FAIL);
}

uint32_t getUs(void) {
	uint32_t usTicks = HAL_RCC_GetSysClockFreq() / 1000000;
	register uint32_t ms, cycle_cnt;
	do {
		ms = HAL_GetTick();
		cycle_cnt = SysTick->VAL;
	} while (ms != HAL_GetTick());

	return (ms * 1000) + (usTicks * 1000 - cycle_cnt) / usTicks;
}

void delayUs(uint32_t micros) {
	uint32_t start = getUs();

	while (getUs()-start < (uint32_t) micros) {
		asm("nop");
	}
}

Thank you
Walter

Thank you kgoveas,
you helped me to focus on the correct part of code where to search for the problem and I finally fixed it.
This is the correct write function:

int8_t bm_spi_write(uint8_t dev_addr, uint8_t reg_addr, const uint8_t *data, uint16_t len) {
	UNUSED(dev_addr);

	if( len > (SPI_BUFF_SZ-1) ) {
		Error_Handler();
	}

	uint8_t txarr[SPI_BUFF_SZ] = { reg_addr };
	memcpy(txarr + 1, data, len);
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_RESET);
	HAL_StatusTypeDef status = HAL_SPI_Transmit(hspi_bmi, txarr, len+1, COMM_DELAY);
	HAL_GPIO_WritePin(SPI_CS_N_GPIO_Port, SPI_CS_N_Pin, GPIO_PIN_SET);
	return (status == HAL_OK ? BMI2_OK : BMI2_E_COM_FAIL);
}

A silly "+1" for the writing buffer lenght was missing in the "HAL_SPI_Transmit" calling.

Best regards,
Walter