STM32MP1 Primer – Day 5

This week's lectures have thus far taught us how to configure and use the STM32MP157x GPIO that is common to both the Cortex-A7 and Cortex-M4 cores. We have also experienced the sensation of sitting on the I2C and USART limbs of the STM32MP157x device tree. Today we will climb the device tree one more time. There's a limb dedicated to providing leaves and branches that enable the STM32MP157x's OpenSTLinux-based SPI peripherals. The configuration of the SPI peripherals within the device tree is quite unique and must be understood thoroughly to enable any of the STM32MP157x SPI peripherals. Today's lecture will be built upon a couple of projects. First, we will code an embedded Linux driver for the popular SSD1306-based display. The SSD1306 is heavily data output-only oriented. The second project will assemble a number of embedded Linux routines designed to drive a MCP23S17 16-bit Expander with Serial Interface. The MCP23S17 driver will contain input capture algorithms as well as standard SPI output routines. Just as we have done all week, we will utilize STM32CubeMX and STM32CubeIDE to generate the device tree assign SPI peripheral GPIO pins and compile our SPI driver source code. The SPI driver code will be capable of interfacing to SPI hardware on the STM32MP157x discovery board's Raspberry Pi 4 and Arduino physical interfaces.