DFRobot FireBeetle ESP32-E Manual page 42

Parameter:
pin：the Arduino pin to write to. Allowed data types: int.
value：the duty cycle: between 0 (always off) and 255 (always on). Allowed data types: int.
8.2 Serial
Serial.begin(speed)
Description: Sets the data rate in bits per second (baud) for serial data transmission. For communicating with Serial Monitor, make sure to
use one of the baud rates listed in the menu at the bottom right corner of its screen.
Parameter:
speed：in bits per second (baud). Allowed data types: long.
Serial.available()
Description: Get the number of bytes (characters) available for reading from the serial port.
Input
Serial.read()
Description: Reads incoming serial data.
Serial.peek()
Description: Returns the next byte (character) of incoming serial data without removing it from the internal serial buffer.
Output
Serial.print(）
Description: Prints data to the serial port
Serial.println()
Description: Prints data to the serial port followed by a carriage return character and a newline character
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