zarthcode / stm32-bme280

Bosch BME280 driver for STM32 using HAL - both SPI and I2C work

stm32-bme280

Bosch BME280 driver for STM32 using HAL
SPI or I2C methods available

This was originally written on an STM32F446RE-Nucleo so its header file is stm32f4xx_hal.h
If you use something like an STM32F103RB, you would need to change that to stm32f1xx_hal.h, or stm32l4xx_hal.h for an STM32L476, et cetera.

This code also assumes that you route printf() to usart2.

My changes were made to bme280_support.c, and the other two files should be identical to the factory Bosch files.

To get SPI working:
comment out the I2C line and uncomment the SPI line in bme280_support.c lines 157/158
set prescaler to 8 or higher, clock polarity to high, and phase to two-edge:

hspi2.Instance = SPI2;
hspi2.Init.Mode = SPI_MODE_MASTER;
hspi2.Init.Direction = SPI_DIRECTION_2LINES;
hspi2.Init.DataSize = SPI_DATASIZE_8BIT;
hspi2.Init.CLKPolarity = SPI_POLARITY_HIGH;
hspi2.Init.CLKPhase = SPI_PHASE_2EDGE;
hspi2.Init.NSS = SPI_NSS_SOFT;
hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_8;
hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi2.Init.CRCPolynomial = 10;

Basically we need to get the SPI clock speed under 10MHz (according to the data sheet, pg.36)
For for a 64mhz stm32f103 running APB1 peripheral bus clock at 32Mhz, use a prescaler of 4 to yield 8 Mb/s SPI clock speed.
It is very helpful to know what clock speed your peripherals run at.

I2C is not nearly as finicky and just works.

Tested and working on an STM32F446RE-Nucleo, and with the minor changes mentioned above (header file and SPI baud rate prescaler), an STM32F103RB-Nucleo.