Writes binary data to the serial port. This data is sent as a byte or series of bytes; to send the characters representing the digits of a number use the print() function instead.
Use the following function variants to write unmodified data to the serial port:
Serial.write(val)Serial.write(str)Serial.write(buf, len)The function admits the following objects and parameters:
Serial: serial port object. See the list of available serial ports for each board on the Serial main page.
val: a value to send as a single byte.
str: a string to send as a series of bytes.
buf: an array to send as a series of bytes.
len: the number of bytes to be sent from the array.
The function returns the number of bytes written, though reading that number is optional. Data type: size_t.
The following code shows how to use Serial.write():
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.write(45); // send a byte with the value 45
int bytesSent = Serial.write("hello"); //send the string "hello" and return the length of the string.
}
Serial transmission is asynchronous. If there is enough empty space in the transmit buffer, Serial.write() will return before any characters are transmitted over serial. If the transmit buffer is full then Serial.write() will block until there is enough space in the buffer. To avoid blocking calls to Serial.write(), you can first check the amount of free space in the transmit buffer using availableForWrite().