Matrix keyboard and 4-key independent keyboard module switchable via jumper

This 4x4 matrix keyboard module can also be switched to a 4-key independent keyboard via a jumper cap.
It also features 8 onboard LEDs driven by a low level.
In the matrix keyboard interface, X represents the row and Y represents the column, with corresponding keys represented by (X,Y) coordinates.
***
The image below shows the jumper position. Shorting pin 2.3 switches to an independent keyboard; keys A-D are in the fourth column and are marked on the key silkscreen.
![image.png] When using the independent keyboard, GND needs to be connected to the microcontroller. When a key is pressed, the corresponding A-D lines (as shown in the image, shared with X1-4 of the matrix keyboard) are low.
![image.png] ***
**Note:**
- Considering that many microcontroller I/O ports already have built-in pull-up resistors, this keyboard module does not include pull-up resistors to simplify the circuit. When configuring I/O ports, the internal pull-up resistors of the chip must be enabled.
- Please adjust the LED current-limiting resistors as needed.