#386 BluePill
Programming an ARM Cortex-M3 STM32F103C8T6 Blue Pill board with the Arduino IDE.
Notes
Popularly known as the Blue Pill, the STM32F103C8T6 Minimum System Development Board seems like an excellent gateway drug for getting into ARM Cortex-M3 development.
This is particularly true as it is possible to program it with the familar Arduino IDE.
This is my first look at one of these boards, so I have simple expectations - follow along some of the tutorials on the web/youtube and at least get a simple program running on the board. In the process I’ll learn a bit more about the board’s capabilities and quirks.
Board Specs
- ARM Cortex M3
- 72 MHz
- 64 KB
- 20 KB RAM
- Reset button
- LED on PIN PC13
- 32 kHz Real time clock crystal
- Jump links on Boot0 and Boot1
- Micro USB connector for power and data
- ST-Link header on the top of the board.
Pinouts
Power
The STM32F103C8 operates from 2.0 to 3.6V. The development board includes a 3.3V LDO regulator, and since many pins are 5V-tolerant, this allows the board to be used with 5V USB power.
Programming with the Arduino IDE
I’m following the STM32 Arduino Tutorial - How to use the STM32F103C8T6 board with the Arduino IDE YouTube tutorial by educ8s.tv. This is one of many, but it is the most accurate and up-to-date that I found in a quick search.
Here’s how the process went for me….
Adding Board Support to the IDE
NB: I’m running Arduino IDE 1.8.2 on MacOSX at the time of this test.
A Boards Manager package is created by Dan Drown, the instructions are on the stm32duino site
Add custom boards package package_STM32duino_index.json in Preferences
Install the STM32F1xx/GD32F1xx boards package by stm32duino in the Board Manager:
Connecting a Serial Programmer
I’m using a CH340G USB-serial adapter from MacOSX (similar but different to FTDI-based adapters).
Connections are as follows:
| USB-Serial | BluePill |
|---|---|
| GND | GND |
| VCC | 5V |
| RXD | A9 |
| TXD | A10 |
Configuring the IDE
The default settings that work with this board are as follows:
- Board: Generic STM32F103C series
- Variant: STM32F103C8 (20k RAM. 64k Flash)
- CPU Speed: 72MHz
- Upload method: Serial
- Port: (as selected based on USB connection)
Uploading Sketch
The Blink.ino sketch is just about the simplest thing possible - blinks the LED connected on port PC13. This is not showing off the board capabilities at all - I’m just trying to verify the programming process.
| BOOT0 | BOOT1 | Mode |
|---|---|---|
| 0 | x | Boot from User Flash. This is normal operating mode. |
| 1 | 0 | Boot from System Memory. This contains the embedded bootloader, and is used for programming |
| 1 | 1 | Boot from embedded SRAM. Used for other STM32 variants, but not the STM32F10x |
For programming, the BluePill Boot0 jumper is set to 1 (pulled high).
From the Arduino IDE, the program compiled and uploaded over serial without any issue..
After disconnecting the serial programmer and switching the BluePill Boot0 jumper to 0 (pulled low), the board can be powered from USB with the program running:
Credits and References
- ARM Cortex-M3 STM32F103C8T6 Minimum System Development Board STM32 - example from a seller on aliexpress
- STM32F103C8 Product Info and Datasheet
- Blue Pill - stm32duino wiki
- Getting Started with STM32F103C8T6 Blue Pill
- Blue Pill Fritzing Part source
- ..as mentioned on my blog