read temperature register, register constants, modified makefile and readme

README.md

@@ -1 +1,10 @@
-# Library for the GY-521 Breakboard
+# Library for the GY-521 Breakboard
+
+## Compiling
+This library depends on the wiringPi library. Make sure to install it first (`sudo apt-get install wiringpi` but often it's preinstalled on raspbian).
+To compile just type `make` in the projects root.
+
+
+
+## Documentation
+[MPU-6050 Datasheet](https://www.olimex.com/Products/Modules/Sensors/MOD-MPU6050/resources/RM-MPU-60xxA_rev_4.pdf)

gy521example.c

@@ -8,7 +8,7 @@ int main(void) {
     setupgy521();
     
     while (1) {
-        printf("AngleX = %f, AngleY = %f, AngleZ = %f\n", getAngleX(), getAngleY(), getAngleZ());
+        printf("AngleX = %f, AngleY = %f, AngleZ = %f, Temperature = %f\n", getAngleX(), getAngleY(), getAngleZ(), getTemp());
         delay(100);
     }
 }

libgy521.c

@@ -7,6 +7,8 @@
 
 //Constants
 
+//######## Obsolete ########//
+
 #define MPU6050_GYRO_XOUT_H 0x43 //R
 #define MPU6050_GYRO_YOUT_H 0x45 //R
 #define MPU6050_GYRO_ZOUT_H 0x47 //R
@@ -18,18 +20,124 @@
 #define MPU6050_PWR_MGMT_1 0x6B //R/W
 #define MPU6050_I2C_ADDRESS 0x68 //I2C
 
+//######## End Obsolete ########//
+
+#define GRAVITIY_MS2                9.80665
+
+// Scale Modifiers
+#define ACCEL_SCALE_MODIFIER_2G     16384.0
+#define ACCEL_SCALE_MODIFIER_4G     8192.0
+#define ACCEL_SCALE_MODIFIER_8G     4096.0
+#define ACCEL_SCALE_MODIFIER_16G    2048.0
+
+#define GYRO_SCALE_MODIFIER_250DEG  131.0
+#define GYRO_SCALE_MODIFIER_500DEG  65.5
+#define GYRO_SCALE_MODIFIER_1000DEG 32.8
+#define GYRO_SCALE_MODIFIER_2000DEG 16.4
+
+// Pre-defined ranges
+#define ACCEL_RANGE_2G              0x00
+#define ACCEL_RANGE_4G              0x08
+#define ACCEL_RANGE_8G              0x10
+#define ACCEL_RANGE_16G             0x18
+
+#define GYRO_RANGE_250DEG           0x00
+#define GYRO_RANGE_500DEG           0x08
+#define GYRO_RANGE_1000DEG          0x10
+#define GYRO_RANGE_2000DEG          0x18
+
+// MPU-6050 Registers
+#define PWR_MGMT_1                  0x6B //R/W
+#define PWR_MGMT_2                  0x6C
+
+#define SELF_TEST_X                 0x0D
+#define SELF_TEST_Y                 0x0E
+#define SELF_TEST_Z                 0x0F
+#define SELF_TEST_A                 0x10
+
+#define ACCEL_XOUT0                 0x3B
+#define ACCEL_XOUT1                 0x3C
+#define ACCEL_YOUT0                 0x3D
+#define ACCEL_YOUT1                 0x3E
+#define ACCEL_ZOUT0                 0x3F
+#define ACCEL_ZOUT1                 0x40
+
+#define TEMP_OUT0                   0x41
+#define TEMP_OUT1                   0x42
+
+#define GYRO_XOUT0                  0x43 //R
+#define GYRO_XOUT1                  0x44
+#define GYRO_YOUT0                  0x45 //R
+#define GYRO_YOUT1                  0x46
+#define GYRO_ZOUT0                  0x47 //R
+#define GYRO_ZOUT1                  0x48
+
+#define ACCEL_CONFIG                0x1C
+#define GYRO_CONFIG                 0x1B
+
 int id;
 
 int setupgy521(void) {
     if ((id = wiringPiI2CSetup(MPU6050_I2C_ADDRESS)) != -1) {
-        wiringPiI2CReadReg8(id, MPU6050_PWR_MGMT_1);
+        wiringPiI2CReadReg8(id, PWR_MGMT_1);
-        wiringPiI2CWriteReg16(id, MPU6050_PWR_MGMT_1, 0);
+        wiringPiI2CWriteReg16(id, PWR_MGMT_1, 0);
         return EXIT_SUCCESS;
     } else {
         return EXIT_FAILURE;
     }
 }
 
+int read_i2c_word(int reg) {
+    return wiringPiI2CReadReg8(id, reg);
+}
+
+int read_i2c_word16(int reg) {
+    return wiringPiI2CReadReg16(id, reg);
+}
+
+float getTemp(void) {
+    /**
+     * Formula given in
+     * MPU-6050 Register Map and Descriptions revision 4.2, page 30
+     */
+    return (read_i2c_word16(TEMP_OUT0) / 340.0) + 36.53; //16 might be bullshit
+}
+
+void setAccelerometerRange(int range) {
+    //First set data to 0x00
+    wiringPiI2CWriteReg8(id, ACCEL_CONFIG, 0x00);
+    //Then write the correct value to the register
+    wiringPiI2CWriteReg8(id, ACCEL_CONFIG, range);
+}
+
+int readAccelerometerRange(int raw) {
+    int rawData = wiringPiI2CReadReg8(id, ACCEL_CONFIG);
+    int range;
+    if (raw != 0) {
+        range = rawData;
+    } else {
+        switch (rawData) {
+            case ACCEL_RANGE_2G:
+                range = 2;
+                break;
+            case ACCEL_RANGE_4G:
+                range = 4;
+                break;
+            case ACCEL_RANGE_8G:
+                range = 8;
+                break;
+            case ACCEL_RANGE_16G:
+                range = 16;
+                break;
+            default:
+                range = -1; //Error
+                break; //Good manner ;)
+        }
+    }
+    
+    return range;
+}
+
 int getGyroX(void) {
     return wiringPiI2CReadReg8(id, MPU6050_GYRO_XOUT_H);
 }

libgy521.h

@@ -8,3 +8,8 @@ int getAccelZ(void);
 float getAngleX(void);
 float getAngleY(void);
 float getAngleZ(void);
+int read_i2c_word(int reg);
+float getTemp(void);
+void setAccelerometerRange(int range);
+int readAccelerometerRange(int raw);
+int read_i2c_word16(int reg);

makefile

@@ -9,7 +9,7 @@ LDFLAGS = -lwiringPi -lm
 
 OBJ = gy521example.o libgy521.o
 
-waterpicore: $(OBJ)
+libgy521: $(OBJ)
 	$(CC) $(CFLAGS) -o gy521example $(OBJ) $(LDFLAGS)
         
 %.o: %.c