Check out example codes for "arduino serial write". It will help you in understanding the concepts better.
Code Example 1
/* 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. */
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