bluetoothhid

Originally I wanted to just make the Bluetooth part directly, but after watching LCEDA's live broadcast explaining the mechanical keyboard, I thought about whether I could make a Bluetooth HDI device? I know that stm32 has USB. After selecting the protocol, you can apply for an HDI device from the computer. And you can apply for several, so that you can connect a homemade keyboard and other BLE devices for serial port debugging. Just go with this idea. I would like to thank Mises for his "ultra-small usb to uart (ttl)" PCB board shape design. I made this open source project based on his shape. It was only after seeing his project that I decided to make such a small Bluetooth device. See the preview below (already printed, but not received yet):

I have already received the board. The 0.8mm thick board made by Jiali Chuang is really small when I get it. Almost all the resistor components used on it are 0201, which is really difficult to solder. You only need tweezers for each one. The tip is big and small. I had to re-solder it several times before finally welding it all. The biggest problem was the step-down lod. It took me 3 pieces of step-down lod to burn before I found the correct pin No. 1 and the direction in the tape. It was wrong, and the silk screen couldn't be seen clearly (it was too small). After a lot of effort, I finally soldered it. The next step was to write a program to drive it. Because the 0201 device is too difficult to solder, the welding video was shot very long, so I will not show the welding video this time. I will solder another one after I finish writing the program, and I bought a new very thin needle tip for use. Let’s apply solder paste. I tried it and was very satisfied. It will definitely be much easier to apply solder paste on the 0201 pad.