arduino serial write
/*
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.
Syntax
Serial.write(val)
Serial.write(str)
Serial.write(buf, len)
Parameters
Serial: serial port object.
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.
*/