Method 

Description 

available 

get the number of bytes(characters)avaiable for reading from the serial port. 

begin 

sets the data rate in bits per sencond for serial data transmission 

end 

disables serial communication, allowing the RX and TX pins to be used for general input and output 

flush 

waits for the transmission of outgoing serial data to complete 

peek 

returns the next byte of incoming serial data without removing it from the internal serial buffer 

read 

reads incoming serial data 

write 

write a char 

Operator 

Description 

bool 

Check if the serail port is ready.
For Serial (USB port), it will check DTR signal to know that if the USB CDC serial connection is established or not (i.e. return true if PC side application opens the corresponding COM port, and return false if the application closes the port).
For Serial1, it will always return true.