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microbit-dal/inc/MicroBitCompass.h

263 lines
7.2 KiB

#ifndef MICROBIT_COMPASS_H
#define MICROBIT_COMPASS_H
#include "mbed.h"
/**
* Relevant pin assignments
*/
#define MICROBIT_PIN_COMPASS_DATA_READY P0_29
/*
* I2C constants
*/
#define MAG3110_DEFAULT_ADDR 0x1D
/*
* MAG3110 Register map
*/
#define MAG_DR_STATUS 0x00
#define MAG_OUT_X_MSB 0x01
#define MAG_OUT_X_LSB 0x02
#define MAG_OUT_Y_MSB 0x03
#define MAG_OUT_Y_LSB 0x04
#define MAG_OUT_Z_MSB 0x05
#define MAG_OUT_Z_LSB 0x06
#define MAG_WHOAMI 0x07
#define MAG_SYSMOD 0x08
#define MAG_OFF_X_MSB 0x09
#define MAG_OFF_X_LSB 0x0A
#define MAG_OFF_Y_MSB 0x0B
#define MAG_OFF_Y_LSB 0x0C
#define MAG_OFF_Z_MSB 0x0D
#define MAG_OFF_Z_LSB 0x0E
#define MAG_DIE_TEMP 0x0F
#define MAG_CTRL_REG1 0x10
#define MAG_CTRL_REG2 0x11
/*
* Compass events
*/
#define MICROBIT_COMPASS_EVT_CAL_REQUIRED 1
#define MICROBIT_COMPASS_EVT_CAL_START 2
#define MICROBIT_COMPASS_EVT_CAL_END 3
/*
* Status Bits
*/
#define MICROBIT_COMPASS_STATUS_CALIBRATED 1
#define MICROBIT_COMPASS_STATUS_CALIBRATING 2
#define MICROBIT_COMPASS_CALIBRATE_PERIOD 10000
/*
* MAG3110 MAGIC ID value
* Returned from the MAG_WHO_AM_I register for ID purposes.
*/
#define MAG3110_WHOAMI_VAL 0xC4
struct CompassSample
{
int16_t x;
int16_t y;
int16_t z;
CompassSample()
{
this->x = 0;
this->y = 0;
this->z = 0;
}
};
/**
* Class definition for MicroBit Compass.
*
* Represents an implementation of the Freescale MAG3110 I2C Magnetmometer.
* Also includes basic caching, calibration and on demand activation.
*/
class MicroBitCompass : public MicroBitComponent
{
/**
* Unique, enumerated ID for this component.
* Used to track asynchronous events in the event bus.
*/
uint16_t address; // I2C address of the magnetmometer.
unsigned long eventStartTime; // used to store the current system clock when async calibration has started
public:
CompassSample minSample; // Calibration sample.
CompassSample maxSample; // Calibration sample.
CompassSample average; // Centre point of sample data.
CompassSample sample; // The latest sample data recorded.
DigitalIn int1; // Data ready interrupt.
/**
* Constructor.
* Create a compass representation with the given ID.
* @param id the event ID of the compass object.
* @param address the default address for the compass register
*
* Example:
* @code
* compass(MICROBIT_ID_COMPASS, MAG3110_DEFAULT_ADDR);
* @endcode
*
* Possible Events for the compass are as follows:
* @code
* MICROBIT_COMPASS_EVT_CAL_REQUIRED // triggered when no magnetometer data is available in persistent storage
* MICROBIT_COMPASS_EVT_CAL_START // triggered when calibration has begun
* MICROBIT_COMPASS_EVT_CAL_END // triggered when calibration has finished.
* @endcode
*/
MicroBitCompass(uint16_t id, uint16_t address);
/**
* Gets the current heading of the device, relative to magnetic north.
* @return the current heading, in degrees.
*
* Example:
* @code
* uBit.compass.heading();
* @endcode
*/
int heading();
/**
* Attempts to determine the 8 bit ID from the magnetometer.
* @return the id of the compass (magnetometer)
*
* Example:
* @code
* uBit.compass.whoAmI();
* @endcode
*/
int whoAmI();
/**
* Reads the X axis value of the latest update from the compass.
* @return The magnetic force measured in the X axis, in no specific units.
*
* Example:
* @code
* uBit.compass.getX();
* @endcode
*/
int getX();
/**
* Reads the Y axis value of the latest update from the compass.
* @return The magnetic force measured in the Y axis, in no specific units.
*
* Example:
* @code
* uBit.compass.getY();
* @endcode
*/
int getY();
/**
* Reads the Z axis value of the latest update from the compass.
* @return The magnetic force measured in the Z axis, in no specific units.
*
* Example:
* @code
* uBit.compass.getZ();
* @endcode
*/
int getZ();
/**
* Perform the asynchronous calibration of the compass.
* This will fire MICROBIT_COMPASS_EVT_CAL_START and MICROBIT_COMPASS_EVT_CAL_END when finished.
* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
*/
void calibrateAsync();
/**
* Perform a calibration of the compass.
* This will fire MICROBIT_COMPASS_EVT_CAL_START.
* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
*/
void calibrateStart();
/**
* Complete the calibration of the compass.
* This will fire MICROBIT_COMPASS_EVT_CAL_END.
* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
*/
void calibrateEnd();
/**
* Periodic callback from MicroBit idle thread.
* Check if any data is ready for reading by checking the interrupt.
*/
virtual void idleTick();
/**
* Returns 0 or 1. 1 indicates that the compass is calibrated, zero means the compass requires calibration.
*/
int isCalibrated();
/**
* Returns 0 or 1. 1 indicates that the compass is calibrating, zero means the compass is not currently calibrating.
*/
int isCalibrating();
/**
* Clears the calibration held in persistent storage, and sets the calibrated flag to zero.
*/
void clearCalibration();
/**
* Returns 0 or 1. 1 indicates data is waiting to be read, zero means data is not ready to be read.
*/
virtual int isIdleCallbackNeeded();
private:
/**
* Issues a standard, 2 byte I2C command write to the magnetometer.
* Blocks the calling thread until complete.
*
* @param reg The address of the register to write to.
* @param value The value to write.
*/
void writeCommand(uint8_t reg, uint8_t value);
/**
* Issues a read command into the specified buffer.
* Blocks the calling thread until complete.
*
* @param reg The address of the register to access.
* @param buffer Memory area to read the data into.
* @param length The number of bytes to read.
*/
void readCommand(uint8_t reg, uint8_t* buffer, int length);
/**
* Issues a read of a given address, and returns the value.
* Blocks the calling thread until complete.
*
* @param reg The based address of the 16 bit register to access.
* @return The register value, interpreted as a 16 but signed value.
*/
int16_t read16(uint8_t reg);
/**
* Issues a read of a given address, and returns the value.
* Blocks the calling thread until complete.
*
* @param reg The based address of the 16 bit register to access.
* @return The register value, interpreted as a 8 bi signed value.
*/
int16_t read8(uint8_t reg);
};
#endif