[Verified] Bluetooth serial port/wireless serial port based on CH582F

Update: The PCB thickness during prototyping was 0.8mm, and the components are based on the schematic. There are also many cheap Bluetooth serial port pass-through chips on Taobao, so this project is more for learning Bluetooth BLE and USB.
I. Chip Introduction
: The CH582 is a RISC-V microcontroller with integrated BLE wireless communication launched by Qinheng (yes, the same Qinheng that made the CH340). It has 448K ROM, 32K SRAM, and low power consumption as low as 0.3uA. It has two embedded USB master/slave controllers, supporting 12Mbps full-speed USB 2.0.
It has both USB and Bluetooth functions, and the number of external components is extremely small, even as low as ¥2.7! (doge)
II. Soldering:
The main chip is in a QFN package, which is very easy to solder as long as the pins are aligned. Although there are few resistors and capacitors on the board, they are all in 0402 packages to keep the size compact, which presents some technical challenges.
At least two chips need to be made: one as the Bluetooth master (solder the USB terminal to plug into the computer), and one as the Bluetooth slave (solder the pin header or socket header to plug into the board). The Bluetooth host requires a 32.768kHz crystal oscillator, while the Bluetooth slave does not (its internal oscillator is enabled in the software). I used a blue LED as the serial port TX indicator; the blue LED lights up whenever UART1 sends data.
When soldering, be extremely careful not to short-circuit the USB mounting pin (circled in red) with the 5V pin header. It's best to use a multimeter to confirm proper soldering before plugging it into the computer.
III. Usage
1. Bluetooth Host (USB):
When the Bluetooth host is plugged into the computer, it will automatically enumerate as CH340, which can be accessed through a serial port assistant. If not connected to a slave, it will continuously scan for nearby devices, and the blue LED will flash regularly. When connected to a slave, the serial port will print the following information indicating a successful connection. After a successful connection, the blue LED will not flash unless data is received.
2. Bluetooth Slave (Pin Header or Female Header):
If you prefer the 5V TX RX GND wiring sequence like I do, it can be directly plugged into the development board. Besides connecting to your own custom Bluetooth host (for ease of use), the Bluetooth slave can also connect to a mobile app or computer program.
The Qinheng Android system BLE debugging tool
and Qinheng's multi-platform Bluetooth development interface library are just demos with relatively simple functions. A more comprehensive host computer would be much more convenient.
3. Baud Rate Modification:
I added baud rate modification functionality to the slave device's data reception code. When the slave device receives an AT command from Bluetooth, it modifies and saves the baud rate. For example, if the host sends AT+BAUD=9600, the slave device will immediately modify the baud rate to 9600 and save it, then return the AT command to the host unchanged, indicating that it received and modified the baud rate.
4. Actual Performance Test
: I short-circuited the RX and TX pins of the Bluetooth slave device, powered it with a power bank, and placed it 3 meters away from the host to test the speed and stability of the wireless serial port. The host sent 560 bytes at a time, once every 100ms, and sent 103408 bytes in 20 seconds. 103408 bytes were sent and received, with no packet loss.
IV. Software
The software is modified from CH583EVT.ZIP version 1.9 by Qinheng.
BLE_UART1 is the modified Bluetooth slave code, and
Central_BLE_USB is the modified Bluetooth master code.
Place these two compressed packages in the EVTEXAMBLE directory after unzipping the Qinheng example files, and you can compile them using MountRiver.
If you don't want to compile, you can directly use WCHISPTool_Setup.exe to burn the hex file under the obj folder.