1、Onboard 4M crystal oscillator, the socket crystal frequency can be replaced at any time. 2、The 4-bit independent keyboard is connected to RB0 RB1 RB2 RB3. 3、8 LEDs are connected to the RD port. When the J3 is plugged in, the LED is enabled. J3 is unplugged and the RD port is completely released. 4、Standard RS232 communication interface, microcontroller board and computer communication interface. 5、External 5V DC power interface (send USB power cable without additional purchase). Feature: Onboard 4M crystal oscillator, the socket crystal frequency can be replaced at any time. The 4-bit independent keyboard is connected to RB0 RB1 RB2 RB3. 8 LEDs are connected to the RD port. When the J3 is plugged in, the LED is enabled. J3 is unplugged and the RD port is completely released. Standard RS232 communication interface, microcontroller board and computer communication interface. External 5V DC power interface (send USB power cable without additional purchase). ICSP programming simulation interface (can be connected to K150 PICKIT2 PICKIT3 ICD2 and other tools). VCC GND pin header power extension interface for access or lead-out of 5 volt power supplies. All IO ports of the MCU are easily extended by using pin headers. Specification: Power supply: USB LCD Interface: LCD1602, LCD12864 Board dimension: 9.2*7.2*1.7cm Package list: 1 * Board 1 * Cable 1 * Board support Note: The actual product color may deviate from the photo due to light. There may be a slight deviation in the measurement of product. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.