STLink-v2.1 (Virtual Serial Port + USB Flash Drive Burning)

In embedded development, a debugger is an indispensable tool.
While Daplink is widely used, its support for new ST features (such as CubeIDE and STM Studio) is not very friendly. However, most of the inexpensive ST-Links available online are version 2, which does not support serial ports and uses cheap, ground-out chips or domestically produced chips, resulting in poor stability. With ST chip prices currently falling, building an inexpensive ST-Link v2.1 debugger is a good option!
Project Overview:
1. This ST-Link v2.1 debugger was designed using LCSC EDA Professional Edition, complying with free prototyping rules;
2. The debugger uses a Type-C interface and supports C-to-C cables (a 5.1k resistor on the back of the Type-C interface needs to be soldered according to the BOM);
3. The entire debugger board is only 40mm*20mm in size, and all resistors and capacitors use 0603 packages, ensuring a compact size and simple soldering;
4. The debugger has clearly marked component information, allowing for easy soldering without referring to the schematic!
 
BOM Cost Overview:
STM32F103CBT6: Average price on Taobao < ¥6
3.3V-LDO: ≈ ¥0.5
Resistors, Capacitors, LEDs, Pin Headers, Terminals, Transistors: ≈ ¥3
PCB: JLCPCB free prototyping ¥0
Overall BOM Cost: < ¥10
 
Firmware Burning Method (STM32CubeProgrammer):
1. Connect the probes of the downloader to the pads on the back of the PCB.
2. After burning the program using CubeProgrammer,
the serial port and debugger will be recognized.
The LED will light up after successful enumeration, and the computer will recognize the USB drive.
 
Precautions:
1. CBT6 must be used; C8T6's Flash size is insufficient for downloading.
2. After downloading the firmware, you can use STM32 ST-LINK Utility for online firmware updates.
3. Due to size limitations, this STLink does not have overcurrent protection circuitry. After manual soldering, please ensure there are no short circuits before powering on to avoid burning out the computer's USB port.