Arduino Uno Quick Start Manual page 50

Chapter 2. Creating Bigger Projects with the Arduino 30
which adds a carriage return character (ASCII code 13) followed by a newline
(ASCII code 10) to the text.
If we receive the character 2, we switch off the LED. If we receive an unsup-
ported command, we send back a corresponding message and the command
we didn t understand. Serial.print works exactly like Serial.println , but it doesn t
add carriage return and newline characters to the message.
Let s see how the program works in practice. Compile it, upload it to your
Arduino, and then switch to the serial monitor. At first glance, nothing hap-
pens. That s because we haven t sent a command to the Arduino yet. Make
sure the drop-down menu at the bottom of the serial monitor is set to No line
ending. Enter a 1 in the text box, and then click the Send button. Two things
should happen now: the LED is switched on, and the message "LED on"
appears in the serial monitor window (as shown in the following image). We
are controlling an LED using our computer s keyboard!
Play around with the commands 1 and 2, and also observe what happens
when you send an unknown command. If you type in an uppercase A, the
Arduino will send back the message "Unknown command: 65." The number
65 is the ASCII code of the letter A, and the Arduino outputs the data it got
in its most basic form. That s the default behavior of Serial s print method, and
you can change it by passing a format specifier to your function calls. To see
the effect, replace line 20 with the following statements:
Serial.println(command, DEC);
Serial.println(command, HEX);
Serial.println(command, OCT);
Serial.println(command, BIN);
Serial.write(command);
Serial.println();
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