This is a low-cost expansion board for micro:bit, which is specifically used for the IO ports of micro:bit. It has expanded all the IO pins on the micro:bit, and also comes with a built-in buzzer. The small size is very suitable for small projects using micro:bit.
The buzzer is connected to the P0 pin. If you remove this jumper cap, it disconnects the connection between the buzzer and P0 pin. The buzzer will not make any sound while you can use P0 pin like other normal IO pin.
At the back of this microbit GPIO Expansion Board, all the pins are labeled with the name and feature it holds like MOSI, MISO, Button A, and Button B so there is no need for you to check on the pinout via Google Image :)
Note:DO NOT place it on a metal surface to avoid a short circuit.
On-board buzzer-you can directly use the music module in MakeCode to play music.
Two LEGO-compatible pin holes for easy assembly and integration
The 3PIN interface is distinguished by yellow (IO pins), red (3.3V), and black (GND). It is created so that plugging it in the wrong way is difficult, and it is convenient to plug in the sensors.