Arduino Uno Quick Start Manual page 187

for the user interface, such as the screen width, the screen height, and the
font size.
After that, we define a few member variables.
to the Serial object we use to communicate with the Arduino.
tains the last temperature value we received from the Arduino, and
is true if the value we read was in degrees Celsius. We need the
to define the font we use to output the temperature on the screen.
In the setup method, we set the window size and create the font we re going to
use. Then we print out a list of all serial devices available. We initialize our
_arduinoPort variable with the first one we find, hoping that it s the Arduino.
You could also loop through the list automatically and search for something
that looks like an Arduino port name, but that d be fragile, too.
We call the clear method to empty the serial port s buffer. With
make sure that we get notified about serial events only when we ve received
a linefeed character. The call to
serial buffer that doesn t contain an incomplete line of data.
centered horizontally and vertically. Eventually, we print the temperature
using the method. To make the result look nicer, we use the official Uni-
text
code characters for degrees Celsius (
Now let s implement the business logic of our "Take me to the beach" alarm:
Ethernet/TweetTemperature/TweetTemperature.pde
void serialEvent(Serial port) {
final String arduinoData = port.readStringUntil(LINE_FEED);
if (arduinoData != null) {
final String[] data = split(trim(arduinoData),
if (data.length == 2 &&
(data[1].equals("C") || data[1].equals("F")))
{
_isCelsius = data[1].equals("C");
_temperature = float(data[0]);
if (Float.isNaN(_temperature))
return;
println(_temperature);
int sleepTime = 5 * 60 * 1000;
if (_temperature > MAX_WORKING_TEMP) {
tweetAlarm();
Chapter 10. Networking with Arduino
_arduinoPort
readStringUntil ensures that we start with a fresh
The draw method prints the last temperature
we received on the screen. It sets the back-
ground color to white using
text color to black using
font and ensures the text we are printing is
\u2103 ) and Fahrenheit (
'
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170
contains a reference
_temperature con-
_isCelsius
_font variable
bufferUntil , we
background and the
fill . Then it sets the
\u2109 ).
');
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