Arduino uno User Manual

for the user interface, such as the screen width, the screen height, and the
font size.
After that, we define a few member variables. _arduinoPort contains a reference
to the Serial object we use to communicate with the Arduino. _temperature con-
tains the last temperature value we received from the Arduino, and _isCelsius
is true if the value we read was in degrees Celsius. We need the _font variable
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 bufferUntil , we
make sure that we get notified about serial events only when we’ve received
a linefeed character. The call to readStringUntil ensures that we start with a fresh
serial buffer that doesn’t contain an incomplete line of data.
The draw method prints the last temperature
we received on the screen. It sets the back-
ground color to white using background and the
text color to black using fill . Then it sets the
font and ensures the text we are printing is
centered horizontally and vertically. Eventually, we print the temperature
using the text method. To make the result look nicer, we use the official Uni-
code characters for degrees Celsius ( \u2103 ) and Fahrenheit ( \u2109 ).
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();
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Arduino uno Specifications

General

Form factor	Arduino
Certification	RoHS, FC, CE
Processor model	-
Processor frequency	- MHz
Microcontroller model	ATmega328
Microcontroller frequency	16 MHz
DC input voltage	7-12 V
Operating voltage	5 V
DC current per I/O pin	40 mA
Flash memory	0.032 MB
Maximum internal memory	- GB
SRAM (Static Random Access Memory)	2 KB
EEPROM (Electrically Erasable Programmable Read-Only Memory)	1 KB
Wi-Fi	No
Number of analog I/O pins	6
Number of digital I/O pins	14

Weight and Dimensions

Board dimensions	53.4 x 68.6 mm