Initial Commit

Java/Processing/processing-3.3.6/modes/java/libraries/io/examples/I2CCompass/I2CCompass.pde

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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;
+}