#386 BluePill

Programming an ARM Cortex-M3 STM32F103C8T6 Blue Pill board with the Arduino IDE.

Build

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

setup_board_manager

Install the STM32F1xx/GD32F1xx boards package by stm32duino in the Board Manager:

setup_install_boards

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

Breadboard

Schematic

Build

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)

setup_serial

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..

serial_programming

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:

BluePill_usb_powered

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

Project Notes