14 digital input/output port: the working voltage is 5V, and the maximum current that each channel can output and access is 40mA. Each circuit is equipped with an internal pull-up resistor of 20-50K ohms (not connected by default). In addition, some pins have specific functions.

Serial signals rx (No.0) and tx (No. 1): serial reception signals providing TTL voltage level are connected to the corresponding pins of FT232Rl.

External Interrupts (No.2 and No.3): Trigger interrupt pin, which can be set as rising edge, falling edge or triggered at the same time.

Pulse width modulation PWM(3, 5, 6, 9, 10, 1 1): six 8-bit PWM outputs are provided.

SPI( 10(SS), 1 1(MOSI), 12(MISO), 13 (SCK)): SPI communication interface.

LED (No. 13): Arduino is specially used to test the reserved interface of LED, which lights up when the output is high and goes out when the output is low.

Six analog inputs A0 to A5: the resolution of each channel is 10 bits (that is, the input has 1024 different values). The default input signal range is 0 to 5V, and the upper input limit can be adjusted by AREF. In addition, some pins have specific functions.

TWI interface (SDA4 and SCL A5): Support communication interface (compatible with I2C bus).

AREF: Reference voltage of analog input signal.

Reset: When the signal is low, reset the MCU chip.

communication interface