USB interface data switch

Features: The USB data pin can be disconnected independently without disconnecting the power supply; it uses relay control.
The principle is very simple, involving only a few switches, relays, a USB port, and indicator lights.
Design rationale: The Arduino main control chip has only one hardware serial port, used for both programming and serial communication. If the program needs to connect to other devices (such as WiFi modules, sensors, etc.) via serial port, the USB cable needs to be unplugged after program upload to prevent the serial port from connecting to the computer, which could prevent normal communication with peripheral devices. However, unplugging the USB cable means disconnecting the 5V power supply, requiring an additional power supply. This project solves this problem by using a switch to disconnect the USB data pin without disconnecting the power supply, or to disconnect the power supply along with the USB cable without unplugging it.
Interfaces: USB Type-B for connecting to the computer, USB Type-A for connecting devices; both support only USB 2.0. A separate 2.54mm header provides a 5V power supply for easy debugging.
Components: 2 toggle switches, 3 relays, 2 LEDs (3mm), 2 color-coded resistors (1/4W, 1kΩ), 1 USB-A female connector bent at 90°, 1 USB-B female connector, 2 2.54mm pin headers. All components can be purchased on Taobao.
With JLCPCB providing free prototyping, the total cost is less than 10 RMB.