ST-LINK V2.1 with interface protection

The ST-Link V2.1 with interface protection uses the STM32F103CBT6 as the main controller. It uses a DC-DC converter to provide 3.3V power for enhanced load capacity, and features electrostatic discharge, overvoltage, and overcurrent protection. It includes a USB-to-serial interface and a JTAG interface for debugging STM microcontrollers via JTAG or SWD. A reset pin prevents jamming. It's a great tool for in-circuit and on-board debugging of STM32 series microcontrollers.

It's best to buy the STM32F103CBT6 from Youxin Electronics to ensure authenticity and avoid problems with substitutes. Since we're only making one, saving a few dollars isn't worthwhile. You can also use the C8T6, but newer firmware versions may be too large to burn.

The attachments include 3D printing files for the casing and PSD files for the stickers (52*32mm). These can be purchased at a printing shop for around 3 yuan. In the 3D printed shell, the top cover can be perfectly matched by embedding a 4mm high M2 thermoplastic nut into a thermoplastic nut and then screwing on a 6mm long countersunk M2 screw.
Images of the thermoplastic nut are attached:
![bandicam 2024-03-30 17-12-32-382.jpg] Sample images after completion:
![c72954fff2b3b92aa4626ce37a67f55.jpg] ![9247cd250a8204887c68b9db090c41e.jpg]
LED explanation (from left to right):
5V, 3.3V, TXD transmit indicator for the virtual serial port, RXD receive indicator, whether data was successfully exchanged with the target chip last time, and data exchange with the PC host in progress.

ST-Link firmware burning tutorial:
1. First, connect an ST-Link chip to the unprogrammed whiteboard according to the silkscreen markings on the SWD interface next to the chip on the board. You can either solder it or press it on with a 1.27mm pitch programming pin (yes, you need an ST-Link first (doge) I got mine for free; but don't worry, I'll introduce a method of programming via serial port later (but it requires more soldering skills)).

2. After connecting, insert the ST-Link into the computer, open ST-LinkUtility, click the third icon from the left at the top, connect to the CBT6 microcontroller, and it should look like this after connection:
![bandicam 2024-03-30 11-40-40-280.jpg]
3. Click Binary File to the right of the Device memory option, and find the J28.M18 firmware in the pop-up file selector.
[Image 1] [Image 2] [Image 3] [Image 4]
4. Click "Burning" (the sixth icon from the left at the top), then click "START
" in the pop-up window. [ Image 5 ] [Image 6] [Image 7] 5. After burning, if the result shown in the image is displayed, the burning was successful. Remove the programmer and insert the USB-C port into the burned ST-Link connector to prepare for firmware updates.
![bandicam 2024-03-30 16-30-31-601.jpg] 6. After connecting the self-made ST-Link, click ST-Link at the top --> Firmware update. In the pop-up window, click device connect. If the ST-Link information is successfully displayed, click YES to update the firmware.
![bandicam 2024-03-30 16-34-20-970.jpg]
Serial port programming tutorial:
1. Using a flying wire method, bring out the PA9, PA10, BOOT0, and BOOT1 pins of the chip, and connect PA9 to the RX terminal of the USB to serial port module, PA10 to the TX terminal of the USB to serial port module; connect BOOT0 to 3.3V, and BOOT1 to GND.
2. At this time, power on and press the reset button. CBT6 enters serial port download mode.
3. Open the FLYMCU software, select the port number and file.
![bandicam 2024-03-30 16-51-22-982.jpg] 4. After clicking "Start Programming," press and hold the RST button on the board for about 1 second, then release. Programming will begin. If an error occurs, try lowering the baud rate.
5. After programming is complete, press the reset button again. The computer should now recognize the ST-LINK, a serial device, and a virtual USB drive. (This assumes the ST-Link driver is correctly installed on the computer.)
![bandicam 2024-03-30 16-57-28-036.jpg]
Reference link:
https://blog.csdn.net/weixin_46251230/article/details/126301012