My musings with STM32

Technical Specifications

Specification	Value
Architecture	32-bit ARM Cortex M3
Operating Voltage	2.7V to 3.6V
CPU Frequency	72 MHz
Number of GPIO pins	37
Number of PWM pins	12
Analog input Pins	10 (12-bit)
USART Peripherals	3
I2C Peripherals	2
SPI Peripherals	2
Can 2.0 Peripheral	1
Timers	3(16-bit), 1 (PWM)
Flash Memory	64KB
RAM	20KB

Get Started

~~Linux driver installation:~~ ~~http://padcom13.blogspot.com/2015/12/getting-started-with-stm32-on-ubuntu.html~~

Windows

Set up STM32CubeMX: https://www.st.com/en/microcontrollers-microprocessors/stm32f103c8.html
Set up TrueSTUDIO: https://atollic.com/truestudio/
Download and install other drivers through intermediate prompts
End to end video tutorial to set up the development environment and getting started with a Blinky project:
Tutorial video to help connect the ST-Link programming unit to the STM32 MCU:
Pinout diagram of the ST-LINK programming unit
Debug to upload the code (.hex file) to STM32 and Resume to actually execute the code on the MCU.

💡

Note that in the programming unit, we connect to the pins 2, 4, 6, 8. The pins are respectively SWCLK, SWDIO, GND, 3.3V. Corresponding are connected in the STM32.

Debugging

Connecting STM32 to PC using Serial Adapter (or Arduino)

Use an Arduino and connect the RESET and GND pins together

Custom Bootloader (Windows App)

https://whuangpro.wordpress.com/2017/10/29/custom-bootloader/

Setup [using `Arduino`] (DID NOT WORK OUT!!)

Connecting through breadboard (some incorrect GND connections here)

Points to note while connecting

Connect the RESET and GND both on Arduino to make it act like a serial adapter.
Connect the GND of STM32 and GND of Arduino.
Connect the 3.3V pin of STM32 to 3.3V pin of Arduino.
Connect the PA9 (Tx) of STM32 to the Rx of Arduino.
Connect the PA10 (Rx) of STM32 to the Tx of Arduino.

❌

This method did NOT work out!! Neither did removing the Atmel IC of the Arduino help.

Setup [using `Serial Adapter / USB2TTL`]

Setup [using `ST-LINK Programming Unit`]

Things to Remember

While programming and testing the STM32 using the serial adapter, it is important to set the boot pins correctly, otherwise results are not correct. Pinout diagram here.
- Programming mode: Boot Pin 0 set to HIGH, Boot Pin 1 set to LOW
- Operation mode: Boot Pin 0 set to LOW, Boot Pin 1 set to LOW

We use FLASHER-STM32 for flashing .bin files to the STM32. Available for Windows.
We use stm32flash for flashing .bin files to the STM32. Cross-platform & well-tested on Arch Linux.
While flashing a .bin file using this software, we Download the File to to the device. This is important.

Talking to STM32 through commands

We can directly send commands through a Serial Terminal (Arduino default, CuteCom etc) and upon sending the correct commands, the STM32 will respond correctly.

Commands

Purpose	Command sent	ACK received	Explanation
Init (must send this first)	0x7F	0x79 (`y`)	`y` means success of the operation
Bootloader version	0x01 0xFE	0x79 (`y`) 0x22 (`"`)	`"` means 0x22 however this might change according to the bootloader version