Erik - / AK8975

Basic library for interfacing the AK8975 using I2C. It does not include more advanced functions. The datasheet does not include what the self-test should return for example, so this library does not include the self-test function.

AK8975.h@0:bceb91239894, 2012-05-07 (annotated)

Committer:
Sissors
Date:
Mon May 07 11:36:18 2012 +0000
Revision:
0:bceb91239894
Child:
1:76f65416ae1b
v1.0

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Sissors 0:bceb91239894 1 /* Library for AK8975 digital compass IC, for use with I2C
Sissors 0:bceb91239894 2
Sissors 0:bceb91239894 3 This library contains basic functionality, if you want more, make it ;)
Sissors 0:bceb91239894 4
Sissors 0:bceb91239894 5
Sissors 0:bceb91239894 6 Example program:
Sissors 0:bceb91239894 7
Sissors 0:bceb91239894 8 #include "mbed.h"
Sissors 0:bceb91239894 9 #include "AK8975.h"
Sissors 0:bceb91239894 10
Sissors 0:bceb91239894 11 DigitalOut led1(LED1);
Sissors 0:bceb91239894 12 Serial pc(USBTX, USBRX); // tx, rx
Sissors 0:bceb91239894 13 AK8975 mag(p9,p10,0x0E);
Sissors 0:bceb91239894 14
Sissors 0:bceb91239894 15
Sissors 0:bceb91239894 16 int main() {
Sissors 0:bceb91239894 17 int data[3];
Sissors 0:bceb91239894 18 if (mag.testConnection())
Sissors 0:bceb91239894 19 pc.printf("Connection succeeded. \n");
Sissors 0:bceb91239894 20 else
Sissors 0:bceb91239894 21 pc.printf("Connection failed. \n");
Sissors 0:bceb91239894 22
Sissors 0:bceb91239894 23 while(1) {
Sissors 0:bceb91239894 24 led1=!led1;
Sissors 0:bceb91239894 25 mag.startMeasurement();
Sissors 0:bceb91239894 26 wait(0.5); //(or use the isReady() function)
Sissors 0:bceb91239894 27 mag.getAll(data);
Sissors 0:bceb91239894 28 pc.printf("X: %d", data[0]);
Sissors 0:bceb91239894 29 pc.putc('\n');
Sissors 0:bceb91239894 30 pc.printf("Y: %d", data[1]);
Sissors 0:bceb91239894 31 pc.putc('\n');
Sissors 0:bceb91239894 32 pc.printf("Z: %d", data[2]);
Sissors 0:bceb91239894 33 pc.putc('\n');
Sissors 0:bceb91239894 34 }
Sissors 0:bceb91239894 35 }
Sissors 0:bceb91239894 36
Sissors 0:bceb91239894 37 */
Sissors 0:bceb91239894 38
Sissors 0:bceb91239894 39 #ifndef AK8975_H
Sissors 0:bceb91239894 40 #define AK8975_H
Sissors 0:bceb91239894 41
Sissors 0:bceb91239894 42 /**
Sissors 0:bceb91239894 43 * Includes
Sissors 0:bceb91239894 44 */
Sissors 0:bceb91239894 45 #include "mbed.h"
Sissors 0:bceb91239894 46
Sissors 0:bceb91239894 47 /**
Sissors 0:bceb91239894 48 * Registers
Sissors 0:bceb91239894 49 */
Sissors 0:bceb91239894 50 #define AK8975_ID_REG 0x00
Sissors 0:bceb91239894 51 #define AK8975_ST1_REG 0x02
Sissors 0:bceb91239894 52 #define AK8975_X_REG 0x03
Sissors 0:bceb91239894 53 #define AK8975_Y_REG 0x05
Sissors 0:bceb91239894 54 #define AK8975_Z_REG 0x07
Sissors 0:bceb91239894 55 #define AK8975_ST2_REG 0x09
Sissors 0:bceb91239894 56 #define AK8975_CONTROL_REG 0x0A
Sissors 0:bceb91239894 57 #define AK8975_SELFTEST_REG 0x0C
Sissors 0:bceb91239894 58
Sissors 0:bceb91239894 59 /**
Sissors 0:bceb91239894 60 * Bits
Sissors 0:bceb91239894 61 */
Sissors 0:bceb91239894 62 #define AK8975_DRDY_BIT 0
Sissors 0:bceb91239894 63 #define AK8975_DERROR_BIT 2
Sissors 0:bceb91239894 64 #define AK8975_OFLOW_BIT 3
Sissors 0:bceb91239894 65
Sissors 0:bceb91239894 66 #define AK8975_SINGLE_MEASUREMENT 1
Sissors 0:bceb91239894 67
Sissors 0:bceb91239894 68 #define AK8975_SENSITIVITY 0.3
Sissors 0:bceb91239894 69
Sissors 0:bceb91239894 70 class AK8975 {
Sissors 0:bceb91239894 71 public:
Sissors 0:bceb91239894 72 /**
Sissors 0:bceb91239894 73 * Constructor.
Sissors 0:bceb91239894 74 *
Sissors 0:bceb91239894 75 * @param sda - mbed pin to use for the SDA I2C line.
Sissors 0:bceb91239894 76 * @param scl - mbed pin to use for the SCL I2C line.
Sissors 0:bceb91239894 77 * @param I2Caddress - the I2C address of the device (0x0C - 0x0F)
Sissors 0:bceb91239894 78 */
Sissors 0:bceb91239894 79 AK8975(PinName sda, PinName scl, char address);
Sissors 0:bceb91239894 80
Sissors 0:bceb91239894 81 /**
Sissors 0:bceb91239894 82 * Checks connection with the device.
Sissors 0:bceb91239894 83 *
Sissors 0:bceb91239894 84 * @return - true if working connection, otherwise false
Sissors 0:bceb91239894 85 */
Sissors 0:bceb91239894 86 bool testConnection( void );
Sissors 0:bceb91239894 87
Sissors 0:bceb91239894 88 /**
Sissors 0:bceb91239894 89 * Checks if measurement is ready
Sissors 0:bceb91239894 90 *
Sissors 0:bceb91239894 91 * @return - true if available measurement, otherwise false
Sissors 0:bceb91239894 92 */
Sissors 0:bceb91239894 93 bool isReady( void );
Sissors 0:bceb91239894 94
Sissors 0:bceb91239894 95 /**
Sissors 0:bceb91239894 96 * Gets the X data
Sissors 0:bceb91239894 97 *
Sissors 0:bceb91239894 98 * @return - signed integer containing the raw data
Sissors 0:bceb91239894 99 */
Sissors 0:bceb91239894 100 int getX( void );
Sissors 0:bceb91239894 101
Sissors 0:bceb91239894 102 /**
Sissors 0:bceb91239894 103 * Gets the Y data
Sissors 0:bceb91239894 104 *
Sissors 0:bceb91239894 105 * @return - signed integer containing the raw data
Sissors 0:bceb91239894 106 */
Sissors 0:bceb91239894 107 int getY( void );
Sissors 0:bceb91239894 108
Sissors 0:bceb91239894 109 /**
Sissors 0:bceb91239894 110 * Gets the Z data
Sissors 0:bceb91239894 111 *
Sissors 0:bceb91239894 112 * @return - signed integer containing the raw data
Sissors 0:bceb91239894 113 */
Sissors 0:bceb91239894 114 int getZ( void );
Sissors 0:bceb91239894 115
Sissors 0:bceb91239894 116 /**
Sissors 0:bceb91239894 117 * Gets all the data, this is more efficient than calling the functions individually
Sissors 0:bceb91239894 118 *
Sissors 0:bceb91239894 119 * @param data - pointer to integer array with length 3 where data is stored (data[0]=X - data[1]=Y - data[2]=Z)
Sissors 0:bceb91239894 120 */
Sissors 0:bceb91239894 121 void getAll( int *data );
Sissors 0:bceb91239894 122
Sissors 0:bceb91239894 123
Sissors 0:bceb91239894 124
Sissors 0:bceb91239894 125 /**
Sissors 0:bceb91239894 126 * Checks if there is a data error due to reading at wrong moment
Sissors 0:bceb91239894 127 *
Sissors 0:bceb91239894 128 * @return - true for error, false for no error
Sissors 0:bceb91239894 129 */
Sissors 0:bceb91239894 130 bool getDataError( void );
Sissors 0:bceb91239894 131
Sissors 0:bceb91239894 132 /**
Sissors 0:bceb91239894 133 * Checks if a magnetic overflow happened (sensor saturation)
Sissors 0:bceb91239894 134 *
Sissors 0:bceb91239894 135 * @return - true for error, false for no error
Sissors 0:bceb91239894 136 */
Sissors 0:bceb91239894 137 bool getOverflow( void );
Sissors 0:bceb91239894 138
Sissors 0:bceb91239894 139 /**
Sissors 0:bceb91239894 140 * Starts a measurement cycle
Sissors 0:bceb91239894 141 */
Sissors 0:bceb91239894 142 void startMeasurement( void );
Sissors 0:bceb91239894 143
Sissors 0:bceb91239894 144
Sissors 0:bceb91239894 145
Sissors 0:bceb91239894 146 private:
Sissors 0:bceb91239894 147 I2C connection;
Sissors 0:bceb91239894 148 char deviceAddress;
Sissors 0:bceb91239894 149
Sissors 0:bceb91239894 150 /**
Sissors 0:bceb91239894 151 * Writes data to the device
Sissors 0:bceb91239894 152 *
Sissors 0:bceb91239894 153 * @param adress - register address to write to
Sissors 0:bceb91239894 154 * @param data - data to write
Sissors 0:bceb91239894 155 */
Sissors 0:bceb91239894 156 void write( char address, char data);
Sissors 0:bceb91239894 157
Sissors 0:bceb91239894 158 /**
Sissors 0:bceb91239894 159 * Read data from the device
Sissors 0:bceb91239894 160 *
Sissors 0:bceb91239894 161 * @param adress - register address to write to
Sissors 0:bceb91239894 162 * @return - data from the register specified by RA
Sissors 0:bceb91239894 163 */
Sissors 0:bceb91239894 164 char read( char adress);
Sissors 0:bceb91239894 165
Sissors 0:bceb91239894 166 /**
Sissors 0:bceb91239894 167 * Read multtiple regigsters from the device, more efficient than using multiple normal reads.
Sissors 0:bceb91239894 168 *
Sissors 0:bceb91239894 169 * @param adress - register address to write to
Sissors 0:bceb91239894 170 * @param length - number of bytes to read
Sissors 0:bceb91239894 171 * @param data - pointer where the data needs to be written to
Sissors 0:bceb91239894 172 */
Sissors 0:bceb91239894 173 void read( char adress, char *data, int length);
Sissors 0:bceb91239894 174 };
Sissors 0:bceb91239894 175 #endif