Arduino uno User Manual

the initialize method once. Then you call update whenever you want the Nunchuk
to send new data. You’ll see the implementation of these two methods shortly.
We have public methods for getting all of the attributes the Nunchuk returns:
the x and y positions of the analog stick, the button states, and the accelera-
tion values of the x-, y-, and z-axes. All of these methods operate on the raw
data you can find in the buffer in line 31. Their implementation is mostly
trivial, and it requires only a single line of code. Only the assembly of the 10-
bit acceleration values needs some tricky bit operations (see Bit Operations,
on page 251).
At the end of the class declaration, you’ll find two private helper methods
named request_data and decode_byte . We need them to implement the initialize and
update methods:
Tinkering/NunchukDemo/nunchuk.cpp
#include <Arduino.h>
Line 1
#include <Wire.h>
-
#include "nunchuk.h"
-
#define NUNCHUK_DEVICE_ID 0x52
-
5
void Nunchuk::initialize() {
-
Wire.begin();
-
Wire.beginTransmission(NUNCHUK_DEVICE_ID);
-
Wire.write((byte)0x40);
-
Wire.write((byte)0x00);
10
Wire.endTransmission();
-
update();
-
}
-
-
bool Nunchuk::update() {
15
delay(1);
-
Wire.requestFrom(NUNCHUK_DEVICE_ID, NUNCHUK_BUFFER_SIZE);
-
int byte_counter = 0;
-
while (Wire.available() && byte_counter < NUNCHUK_BUFFER_SIZE)
-
_buffer[byte_counter++] = decode_byte(Wire.read());
20
request_data();
-
return byte_counter == NUNCHUK_BUFFER_SIZE;
-
}
-
-
void Nunchuk::request_data() {
25
Wire.beginTransmission(NUNCHUK_DEVICE_ID);
-
Wire.write((byte)0x00);
-
Wire.endTransmission();
-
}
-
30
char Nunchuk::decode_byte(const char b) {
-
return (b ^ 0x17) + 0x17;
-
}
-
Chapter 9. Tinkering with the Wii Nunchuk • 150
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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