Better Control: An MCU on the board controls the LED, and the IO port can be connected to P3.2 for output, such as PWM wave modulation experiments. One-Way Switch: A single-channel switch chip on the board, connected to IO port P3.3, can be used for input, interrupts, and other experiments. Stable Work: The switches and LEDs on the external circuits of the IO port do not affect the normal use of the IO port. 4 Sets Total: There are 4 sets of MCU development boards, and the large quantity will meet your replacement needs. All IO Ports Brought Out: All IO ports are brought out, making the lightweight and compact microcontroller board easy to install. Item Type: Microcontroller Board Material: PCB Board Size: Approx. 12 x 18 mm / 0.47 x 0.71 inches 4 x Microcontroller Board 4 x Pin Header