Arduino uno User Manual

First of all, you should note that we define all methods on the prototype prop-
erty of the SerialDevice object. I won’t go into the details here, but you should
know that this is one way to add new methods to objects in JavaScript.
The connect method delegates its work to the chrome.serial.connect function that
you saw in the previous section already. The only thing worth noting is the
callback function we pass in the function call. Again we use bind to set the
callback function’s context explicitly. This way, we make sure that onConnect-
Complete has access to the properties of the SerialDevice object.
We benefit from that in the onConnectComplete method. Here we can set the con-
nectionId property of our SerialDevice object as soon as we’ve successfully connect-
ed to a serial device. If we hadn’t bound onConnectComplete before, this would
have a completely different meaning in this function, and we couldn’t access
the properties of the SerialDevice object.
In lines 14 and 15, we use the same technique to add receive and error listen-
ers to the chrome.serial object. Here we use the listeners we’ve prepared in the
constructor function before. After we’ve established the connection success-
fully, we call the onConnect object’s dispatch method to spread the good news to
all listeners outside.
Eventually, we have to implement the actual listener functions that deal with
incoming and outgoing data and with errors:
ChromeApps/SerialDevice/js/serial_device.js
SerialDevice.prototype.onReceive = function(receiveInfo) {
if (receiveInfo.connectionId !== this.connectionId) {
return;
}
this.readBuffer += this.arrayBufferToString(receiveInfo.data);
var n;
while ((n = this.readBuffer.indexOf('\n')) >= 0) {
var line = this.readBuffer.substr(0, n + 1);
this.onReadLine.dispatch(line);
this.readBuffer = this.readBuffer.substr(n + 1);
}
};
SerialDevice.prototype.onReceiveError = function(errorInfo) {
if (errorInfo.connectionId === this.connectionId) {
this.onError.dispatch(errorInfo.error);
}
};
SerialDevice.prototype.send = function(data) {
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Writing a SerialDevice Class • 277
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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