[Physical product verified] JLink OB With CDC_GD32_Series 4

This hardware design is completely open source and can be used for personal use and not for commercial use . Please respect the spirit of open source hardware!

The software part comes from the Internet . If there is any infringement, please contact me to delete the software attachments.

Friends who like my projects can follow the collection and like it:)

There are 4 issues in this series, and this issue is the 4th:

The address of the first issue: https://oshwhub.com/duyes/jlink-zui-xiao-ban

Address for the second phase: https://oshwhub.com/duyes/jlink-zui-xiao-wai-wei-ban

The third phase address: https://oshwhub.com/duyes/jlink-zui-xiao-wai-wei-ban_copy

In fact, after completing the first three issues, I feel that JLINK is basically ready for use. Anyway, there are also STM32 and GD32 ones. But group friends joked that there is no CDC for this thing~

What is CDC? To put it simply, it is a virtual serial port . You need to use the serial port when downloading the STM or downloading the 51 microcontroller and 8266. So can our GD32 device complete serial port downloading?

After searching for resources on the Internet, I didn't expect that this solution actually existed.

The principle diagram of the original plan is a bit confusing. Multiple MCUs coexist. The PCB diagram is drawn by AD. There is only one MCU. There is no other way but to make a V1.0 version for testing first!

V1.0 has been deleted by me, so I won’t put pictures here.

The point is that after testing the V1.0 version, I found that this solution is feasible, and it is indeed possible to make JLINK with CDC!

Subsequently, the solution was optimized and the V2.0 board was released.

After V2.0 was made, I found that it was completely useless to leave the serial port for downloading for the programming interface, because the firmware in the attachments provided by the website could not be downloaded using the serial port. It still had to be downloaded through SWD. In addition, this 6-pin I don’t like the wiring method anymore. I copied Ji Xiaoxin’s output pin and made a double row of pins attached to the PCB board. Redesign V3.0!

After several revisions, version V3.0 is finally perfect. It can do both SWD download and serial port download!

The point is that the price of this GD32F103RET6 is not very expensive.

The following is the actual welding drawing:

Things to note:

1. The virtual serial port will display ❗️ on a computer with a Microsoft certified signature. You need to turn off the Windows signature for the driver to work properly;

2. The serial port download baud rate can be adjusted according to the software and chip needs;

3.SWD download speed is 4M, which is almost the highest speed of the OB series;

4. The burning method is basically the same as the previous three periods, and there is not much difference;

5. Because the output terminal uses a double row of 2*5P pins, in actual use, you can consider welding a calf-horn socket to achieve fool-proof insertion;

6. This time the board crystal oscillator uses Murata Ceramics 3213 12M crystal oscillator;

7. Because R7 1.5K is relatively rare, you can also use 2K instead;

8. The current limiting resistor of each LED can be adjusted according to the brightness that netizens prefer;

9. I haven’t thought of it for the moment, I look forward to your friends adding:)

Finally, I will upload my own finished picture. If you don’t understand, please click and leave a message.

Engineering friends who like me can follow the collection and like it:)

Finally, let me give you a preview. I am currently drawing an STM32F103RET6 core board that integrates SWD and serial port downloading . Every time I use it, I only need to plug in a TYPEC cable to complete SWD downloading or serial port downloading . The downloading part is the circuit used in this article. Friends who like it please follow me!