[Verified] High-quality J-Link_V9_Base with protection

Project Summary:
       This is a verified J-LinkV9 based on the open-source project by @Travellium. The schematic has been modified, and the board has been redrawn as a double-sided board for easy customization of silkscreen colors.
Specific hardware changes include:
1. Modifying the 3.3V reference voltage output capability by adding a protected 3.3V LDO output. The isolated version is limited to 300mA, and the through version to 400mA, allowing direct power supply to low-power loads during J-Link debugging.
2. Adding ESD protection to the data interface, and TVS diodes and fuses to the power outputs to minimize the possibility of backflow voltage from the debugged device when used as a through version.
3. Isolating the 3.3V output from the microcontroller's 3.3V power supply to prevent damage to the controller from low-voltage backflow (in reality, genuine 32-bit microcontrollers are quite durable and generally won't be damaged by electrical shock).
4. Integrating the isolated and through versions onto a single board, allowing users to use resistors as jumpers to determine whether to use it as an isolated or through version, thus reducing costs. (However, please note: Since the through-type and isolation types are on the same board, the gap withstand voltage cannot meet the 2.5KV isolation requirement. It is also not recommended to debug microcontrollers related to mains power (such as digital power supplies); the intended application is debugging brushless motor drivers, etc.; otherwise, user safety cannot be guaranteed!!!)
 
Fabrication and Assembly:
1. Soldering:
1. It is recommended to solder the STM32F205RET6, seven SN74LVC2T45DCRUs, and three ESD diode arrays first. Otherwise, a larger soldering iron tip will be difficult to insert when soldering other components later. It is recommended to use drag soldering for the STM32 and SN74. Other components can be soldered using solder paste + hot plate soldering.
2. If you do not intend to use the ADUM3160, simply solder 0-ohm resistors to the four 1206 resistor pads under the ADUM3160 to short-circuit them. (As shown in the picture, the top is the through board, and the bottom is the isolation board)
3. For the tail pin header, it is recommended to insert the pin header into the socket after printing out the outer shell, and then put the board into the outer shell before soldering. Otherwise, it is easy to solder crookedly (both of mine were crooked).
2. Debugging (important):
1. After completion, the inside of the chip is empty. It will not be recognized after being plugged in. You need to use the debugging pad reserved in the upper left corner of the board to first burn the bootloader; then plug it into the computer, and use the host computer to flash the firmware. Finally, write the serial number and function. 
      First, burn the bootloader. Use a burning clip (as shown in the picture) or solder to connect 3.3V, GND, SWDIO, and SWCLK to ST-LINK respectively. Open ST-Link Unification or STM32CubeProgrammer, and burn the bootloader.bin file in the attachment into the STM32F205RET6.
There are many online resources detailing the flashing process, so I won't go into detail here (mainly because I forgot to take pictures at the time >﹏＜).
2. Go to SEGGER's official website (here ヾ(•ω•`)o), download the J-Link driver, and install it. Plug the prepared J-Link into your computer (remember to use a multimeter to check for short circuits first). Under normal circumstances, Device Manager should show that the J-Link is connected; then open J-Link Commander.exe in the attachment. It will prompt that the connected J-Link is in bootloader mode and requires firmware flashing to function properly; click Yes, and the firmware will be automatically flashed to the J-Link. After plugging and unplugging again, the J-Link should be recognized normally.
3. Open the J-Link Commander in the attachment and enter the following statements to add functions and write the SN code:
Run the following commands in sequence under the J   -Link command
. Please use the SN code from the following links to flash the SN:
Link A
Link B
Do not use the SN in the example, as it will report a clone and cause online debugging and other functions to be unusable.
Exec SetSN=59788888 ; Add SN 
Exec AddFeature GDB ; Add GDB 
Exec AddFeature RDI ; Add RDI 
Exec AddFeature FlashBP ; Add FlashBP  
Exec AddFeature FlashDL ; Add FlashDL 
Exec AddFeature JFlash ; Add JFlash 
//Do not add RDDI otherwise it will report cloning
//Exec AddFeature RDDI ; Add RDDI
//Check if the SN code is correctly flashed (you can also unplug and plug in the USB again, and the SN code will be displayed after connection)
Exec GetSNChecksum
Reference link: here (￣︶￣)↗　
Then, after downloading the driver, the new version of J-Link Commander that appears on the computer can be opened to update the firmware to version 9.7 normally. Executing power on perm can enable 5V output by default.
 
4. According to the SWD interface or other interfaces, use J-Link Commander or STM32CubeProgrammer (you need to select J-Link as the programmer) to find an STM32F103 to verify the function. (Don't forget to connect the reference voltage to VREF, otherwise the level conversion chip will not work properly without a reference voltage.)
 
3. Housing Assembly and Finishing (Optional):
1. Actually, it can be used normally after the previous step, but if you don't want the debugger to run naked, or can't remember the pin definitions, or think it's too ugly, you can make a housing.
       After 3D printing the housing file in the attachment, use an M2, 3mm diameter, 4mm high thermoforming nut; use a round-head soldering iron to press it into the top cover, put the made J-Link into the bottom cover (may require some force), and use M2*8mm countersunk screws to connect the top and bottom covers. Find a print shop and have them print the sticker document in the attachment according to the requirements, cut it yourself, and stick it on the front of the debugger to get a high-quality J-Link.