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processing4/java/libraries/io/examples/I2CCompass/I2CCompass.pde
2016-02-14 11:37:30 +01:00

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import processing.io.*;
I2C i2c;
// HMC6352 is a digital compass module using I2C
// datasheet: https://www.sparkfun.com/datasheets/Components/HMC6352.pdf
// see setup.png in the sketch folder for wiring details
void setup() {
//printArray(I2C.list());
i2c = new I2C(I2C.list()[0]);
setHeadingMode();
}
void draw() {
background(255);
float deg = getHeading();
println(deg + " degrees");
line(width/2, height/2, width/2+sin(radians(deg))*width/2, height/2-cos(radians(deg))*height/2);
}
void setHeadingMode() {
i2c.beginTransmission(0x21);
// command byte for writing to EEPROM
i2c.write(0x77);
// address of the output data control byte
i2c.write(0x4e);
// give us the plain heading
i2c.write(0x00);
i2c.endTransmission();
}
float getHeading() {
i2c.beginTransmission(0x21);
// command byte for reading the data
i2c.write(0x41);
byte[] in = i2c.read(2);
i2c.endTransmission();
// put bytes together to tenth of degrees
// & 0xff makes sure the byte is not interpreted as a negative value
int deg = (in[0] & 0xff) << 8 | (in[1] & 0xff);
// return degrees
return deg / 10.0;
}