STM32F407G-DISC1 | STM32F4 microprocessor via the Embedded.fm

I have the following: STM32F407G-DISC1. My goal is to communicate (sending strings back and forth) between my pc and the mcu over serial and I currently am able to do so using the micro-usb (otg) port, while powering separately using the mini-usb st-link port (so using two cables).

Is it possible to use the mini-usb port for serial communications? (eliminating one of the cables)

I have read the user manual and my interpretation is that this is not possible without physical modifications. But I am a beginner and would like to verify I am correct in this interpretation. I have researched thoroughly however most sources seem to not refer to this specific board and it is my understanding with the newer version of st-link it uses this should be achievable.

So I'm learning embedded development, and I recently learned the basics of SPI. As a project, I wanted to communicate with the LIS3DSH accelerometer on my STM32F407G-DISC1 board using only the CMSIS headers.

I pasted the entire code below, but I'll explain it first because no one wants to read all that code.

As a reference, these are the pins needed (according to the MCU's datasheet) to communicate via SPI:

• PA5 - SPI1_SCK
• PA7 - SPI1_MOSI
• PA6 - SPI1_MISO
• PE3 - CS_I2C/SPI

Here's the steps I took in my code:

1. Enabled the clock for GPIOA and GPIOE using the AHB1ENR register.
2. For GPIOA, I set the three pins as alternate function, output is push-pull, speed is low, no pull-up/pull-down, and configured the alternate function as SPI.
3. For GPIOE, set it as GPIO mode, push-pull, low speed, pull-up, and then set it high (as in wrote to the BSSR register).
4. Enabled the clock for SPI using the APB2ENR register.
5. Configured SPI1: first disabled it, enabled 2-line unidirectional mode, set baud rate to fPCL/16 since the APB2 peripheral clock is 84MHz and the max clock of the accelerometer is 10MHz. Then set clock phase and polarity to 1. 8-bit data frame, MSB first, enabled software slave management, and also enabled master configuration. Finally, enabled SPI1.
6. After all this, I transmit 0x63 to the 0x20 register of the accelerometer. This sets the output rate to 100Hz and enables both the x and y axis. I have no idea if this is actually working. I'm assuming it is because the TX buffer is empty when I check the SPI status register.
7. Then to test whether I can recieve, I attempt to get the data from the WHO_AM_I register of the accelerometer. But I only see garbage data when I debug it (0xFF).

I've googled around to see why this may be, and a lot of people suggested that the clock polarity and phase may be incorrect. However, I've checked it multiple times, and I'm fairly certain I configured it properly.

I've tried setting interrupts. During the interrupt, even though RXNE (RX buffer not empty) is true, it still reads only 0xFF. I'm stumped as to why this is happening.

The code is below. The starting point is accelerometer_init(). The reading of the data from the WHO_AM_I register is in turn_on_accelerometer().