Update AK8975 datatypes and examples

Arduino/AK8975/AK8975.cpp

@@ -147,13 +147,13 @@ void AK8975::disableI2C() {
 }
 
 // ASA* registers
-void AK8975::getAdjustment(uint8_t *x, uint8_t *y, uint8_t *z) {
+void AK8975::getAdjustment(int8_t *x, int8_t *y, int8_t *z) {
     I2Cdev::readBytes(devAddr, AK8975_RA_ASAX, 3, buffer);
     *x = buffer[0];
     *y = buffer[1];
     *z = buffer[2];
 }
-void AK8975::setAdjustment(uint8_t x, uint8_t y, uint8_t z) {
+void AK8975::setAdjustment(int8_t x, int8_t y, int8_t z) {
     buffer[0] = x;
     buffer[1] = y;
     buffer[2] = z;

Arduino/AK8975/AK8975.h

@@ -117,8 +117,8 @@ class AK8975 {
         void disableI2C(); // um, why...?
 
         // ASA* registers
-        void getAdjustment(uint8_t *x, uint8_t *y, uint8_t *z);
-        void setAdjustment(uint8_t x, uint8_t y, uint8_t z);
+        void getAdjustment(int8_t *x, int8_t *y, int8_t *z);
+        void setAdjustment(int8_t x, int8_t y, int8_t z);
         uint8_t getAdjustmentX();
         void setAdjustmentX(uint8_t x);
         uint8_t getAdjustmentY();

Arduino/AK8975/Examples/AK8975_MPUEVB_heading/AK8975_MPUEVB_heading.ino

@@ -0,0 +1,118 @@
+// I2C device class (I2Cdev) demonstration Arduino sketch for AK8975 class
+// 6/11/2012 by Jeff Rowberg <jeff@rowberg.net>
+// Updates should (hopefully) always be available at https://github.com/jrowberg/i2cdevlib
+//
+// This example uses the AK8975 as mounted on the InvenSense MPU-6050 Evaluation
+// Board, and as such also depends (minimally) on the MPU6050 library from the
+// I2Cdevlib collection. It initializes the MPU6050 and immediately enables its
+// "I2C Bypass" mode, which allows the sketch to communicate with the AK8975
+// that is attached to the MPU's AUX SDA/SCL lines. The AK8975 is configured on
+// this board to use the 0x0E address.
+//
+// Note that this small demo does not make use of any of the MPU's amazing
+// motion processing capabilities (the DMP); it only provides raw sensor access
+// to the compass as mounted on that particular evaluation board.
+//
+// For more info on the MPU-6050 and some more impressive demos, check out the
+// device page on the I2Cdevlib website:
+//     http://www.i2cdevlib.com/devices/mpu6050
+//
+// Changelog:
+//     2012-06-11 - initial release
+
+/* ============================================
+I2Cdev device library code is placed under the MIT license
+Copyright (c) 2012 Jeff Rowberg
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+===============================================
+*/
+
+// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
+// is used in I2Cdev.h
+#include "Wire.h"
+
+// I2Cdev, AK8975, and MPU6050 must be installed as libraries, or else the
+// .cpp/.h files for all classes must be in the include path of your project
+#include "I2Cdev.h"
+#include "AK8975.h"
+#include "MPU6050.h"
+
+// class default I2C address is 0x0C
+// specific I2C addresses may be passed as a parameter here
+// Addr pins low/low = 0x0C
+// Addr pins low/high = 0x0D
+// Addr pins high/low = 0x0E (default for InvenSense MPU6050 evaluation board)
+// Addr pins high/high = 0x0F
+AK8975 mag(0x0E);
+MPU6050 accelgyro; // address = 0x68, the default, on MPU6050 EVB
+
+int16_t mx, my, mz;
+float heading;
+
+#define LED_PIN 13
+bool blinkState = false;
+
+void setup() {
+    // join I2C bus (I2Cdev library doesn't do this automatically)
+    Wire.begin();
+
+    // initialize serial communication
+    // (38400 chosen because it works as well at 8MHz as it does at 16MHz, but
+    // it's really up to you depending on your project)
+    Serial.begin(38400);
+
+    // initialize devices
+    Serial.println("Initializing I2C devices...");
+
+    // initialize MPU first so we can connect the AUX lines
+    accelgyro.initialize();
+    accelgyro.setI2CBypassEnabled(true);
+    mag.initialize();
+
+    // verify connection
+    Serial.println("Testing device connections...");
+    Serial.println(mag.testConnection() ? "AK8975 connection successful" : "AK8975 connection failed");
+
+    // configure Arduino LED for
+    pinMode(LED_PIN, OUTPUT);
+}
+
+void loop() {
+    // read raw heading measurements from device
+    mag.getHeading(&mx, &my, &mz);
+
+    // display tab-separated gyro x/y/z values
+    Serial.print("mag:\t");
+    Serial.print(mx); Serial.print("\t");
+    Serial.print(my); Serial.print("\t");
+    Serial.print(mz); Serial.print("\t\t");
+
+    heading = atan2((double)my, (double)mx) * 180.0/3.14159265 + 180;
+    while (heading < 0) heading += 360;
+    while (heading > 360) heading -= 360;
+    Serial.print(heading);
+    Serial.println(" degrees");
+
+    // blink LED to indicate activity
+    blinkState = !blinkState;
+    digitalWrite(LED_PIN, blinkState);
+
+    delay(100); // run at ~10 Hz
+}