313 lines
9.5 KiB
C++
313 lines
9.5 KiB
C++
#ifndef MICROBIT_COMPASS_H
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#define MICROBIT_COMPASS_H
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#include "mbed.h"
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#include "MicroBitComponent.h"
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/**
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* Relevant pin assignments
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*/
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#define MICROBIT_PIN_COMPASS_DATA_READY P0_29
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/*
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* I2C constants
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*/
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#define MAG3110_DEFAULT_ADDR 0x1D
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/*
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* MAG3110 Register map
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*/
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#define MAG_DR_STATUS 0x00
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#define MAG_OUT_X_MSB 0x01
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#define MAG_OUT_X_LSB 0x02
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#define MAG_OUT_Y_MSB 0x03
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#define MAG_OUT_Y_LSB 0x04
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#define MAG_OUT_Z_MSB 0x05
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#define MAG_OUT_Z_LSB 0x06
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#define MAG_WHOAMI 0x07
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#define MAG_SYSMOD 0x08
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#define MAG_OFF_X_MSB 0x09
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#define MAG_OFF_X_LSB 0x0A
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#define MAG_OFF_Y_MSB 0x0B
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#define MAG_OFF_Y_LSB 0x0C
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#define MAG_OFF_Z_MSB 0x0D
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#define MAG_OFF_Z_LSB 0x0E
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#define MAG_DIE_TEMP 0x0F
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#define MAG_CTRL_REG1 0x10
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#define MAG_CTRL_REG2 0x11
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/**
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* Configuration options
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*/
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struct MAG3110SampleRateConfig
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{
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uint32_t sample_period;
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uint8_t ctrl_reg1;
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};
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extern const MAG3110SampleRateConfig MAG3110SampleRate[];
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#define MAG3110_SAMPLE_RATES 11
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/*
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* Compass events
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*/
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#define MICROBIT_COMPASS_EVT_CAL_REQUIRED 1
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#define MICROBIT_COMPASS_EVT_CAL_START 2
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#define MICROBIT_COMPASS_EVT_CAL_END 3
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#define MICROBIT_COMPASS_EVT_DATA_UPDATE 4
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#define MICROBIT_COMPASS_EVT_CONFIG_NEEDED 5
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/*
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* Status Bits
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*/
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#define MICROBIT_COMPASS_STATUS_CALIBRATED 1
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#define MICROBIT_COMPASS_STATUS_CALIBRATING 2
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#define MICROBIT_COMPASS_CALIBRATE_PERIOD 10000
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/*
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* MAG3110 MAGIC ID value
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* Returned from the MAG_WHO_AM_I register for ID purposes.
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*/
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#define MAG3110_WHOAMI_VAL 0xC4
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struct CompassSample
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{
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int16_t x;
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int16_t y;
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int16_t z;
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CompassSample()
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{
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this->x = 0;
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this->y = 0;
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this->z = 0;
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}
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};
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/**
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* Class definition for MicroBit Compass.
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*
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* Represents an implementation of the Freescale MAG3110 I2C Magnetmometer.
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* Also includes basic caching, calibration and on demand activation.
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*/
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class MicroBitCompass : public MicroBitComponent
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{
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/**
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* Unique, enumerated ID for this component.
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* Used to track asynchronous events in the event bus.
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*/
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uint16_t address; // I2C address of the magnetmometer.
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uint16_t samplePeriod; // The time between samples, in millseconds.
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unsigned long eventStartTime; // used to store the current system clock when async calibration has started
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CompassSample minSample; // Calibration sample.
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CompassSample maxSample; // Calibration sample.
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CompassSample average; // Centre point of sample data.
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CompassSample sample; // The latest sample data recorded.
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DigitalIn int1; // Data ready interrupt.
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public:
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/**
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* Constructor.
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* Create a compass representation with the given ID.
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* @param id the event ID of the compass object.
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* @param address the default address for the compass register
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*
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* Example:
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* @code
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* compass(MICROBIT_ID_COMPASS, MAG3110_DEFAULT_ADDR);
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* @endcode
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*
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* Possible Events for the compass are as follows:
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* @code
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* MICROBIT_COMPASS_EVT_CAL_REQUIRED // triggered when no magnetometer data is available in persistent storage
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* MICROBIT_COMPASS_EVT_CAL_START // triggered when calibration has begun
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* MICROBIT_COMPASS_EVT_CAL_END // triggered when calibration has finished.
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* @endcode
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*/
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MicroBitCompass(uint16_t id, uint16_t address);
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/**
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* Configures the compass for the sample rate defined
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* in this object. The nearest values are chosen to those defined
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* that are supported by the hardware. The instance variables are then
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* updated to reflect reality.
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* @return MICROBIT_OK or MICROBIT_I2C_ERROR if the magnetometer could not be configured.
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*/
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int configure();
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/**
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* Attempts to set the sample rate of the compass to the specified value (in ms).
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* n.b. the requested rate may not be possible on the hardware. In this case, the
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* nearest lower rate is chosen.
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* @param period the requested time between samples, in milliseconds.
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* @return MICROBIT_OK or MICROBIT_I2C_ERROR if the magnetometer could not be updated.
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*/
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int setPeriod(int period);
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/**
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* Reads the currently configured sample rate of the compass.
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* @return The time between samples, in milliseconds.
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*/
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int getPeriod();
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/**
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* Gets the current heading of the device, relative to magnetic north.
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* @return the current heading, in degrees. Or MICROBIT_COMPASS_IS_CALIBRATING if the compass is calibrating.
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* Or MICROBIT_COMPASS_CALIBRATE_REQUIRED if the compass requires calibration.
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*
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* Example:
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* @code
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* uBit.compass.heading();
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* @endcode
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*/
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int heading();
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/**
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* Attempts to determine the 8 bit ID from the magnetometer.
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* @return the id of the compass (magnetometer), or MICROBIT_I2C_ERROR if the magnetometer could not be updated.
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*
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* Example:
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* @code
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* uBit.compass.whoAmI();
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* @endcode
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*/
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int whoAmI();
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/**
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* Reads the X axis value of the latest update from the compass.
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* @return The magnetic force measured in the X axis, in no specific units.
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*
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* Example:
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* @code
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* uBit.compass.getX();
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* @endcode
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*/
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int getX();
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/**
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* Reads the Y axis value of the latest update from the compass.
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* @return The magnetic force measured in the Y axis, in no specific units.
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*
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* Example:
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* @code
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* uBit.compass.getY();
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* @endcode
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*/
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int getY();
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/**
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* Reads the Z axis value of the latest update from the compass.
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* @return The magnetic force measured in the Z axis, in no specific units.
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*
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* Example:
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* @code
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* uBit.compass.getZ();
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* @endcode
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*/
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int getZ();
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/**
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* Reads the currently die temperature of the compass.
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* @return the temperature in degrees celsius, or MICROBIT_I2C_ERROR if the magnetometer could not be updated.
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*/
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int readTemperature();
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/**
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* Perform the asynchronous calibration of the compass.
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* This will fire MICROBIT_COMPASS_EVT_CAL_START and MICROBIT_COMPASS_EVT_CAL_END when finished.
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* @return MICROBIT_OK, or MICROBIT_I2C_ERROR if the magnetometer could not be accessed.
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* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
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*/
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void calibrateAsync();
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/**
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* Perform a calibration of the compass.
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* This will fire MICROBIT_COMPASS_EVT_CAL_START.
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* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
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*/
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int calibrateStart();
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/**
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* Complete the calibration of the compass.
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* This will fire MICROBIT_COMPASS_EVT_CAL_END.
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* @note THIS MUST BE CALLED TO GAIN RELIABLE VALUES FROM THE COMPASS
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*/
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void calibrateEnd();
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/**
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* Periodic callback from MicroBit idle thread.
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* Check if any data is ready for reading by checking the interrupt.
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*/
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virtual void idleTick();
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/**
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* Returns 0 or 1. 1 indicates that the compass is calibrated, zero means the compass requires calibration.
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*/
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int isCalibrated();
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/**
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* Returns 0 or 1. 1 indicates that the compass is calibrating, zero means the compass is not currently calibrating.
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*/
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int isCalibrating();
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/**
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* Clears the calibration held in persistent storage, and sets the calibrated flag to zero.
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*/
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void clearCalibration();
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/**
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* Returns 0 or 1. 1 indicates data is waiting to be read, zero means data is not ready to be read.
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*/
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virtual int isIdleCallbackNeeded();
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private:
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/**
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* Issues a standard, 2 byte I2C command write to the magnetometer.
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* Blocks the calling thread until complete.
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*
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* @param reg The address of the register to write to.
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* @param value The value to write.
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* @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if the magnetometer could not be accessed.
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*/
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int writeCommand(uint8_t reg, uint8_t value);
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/**
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* Issues a read command into the specified buffer.
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* Blocks the calling thread until complete.
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*
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* @param reg The address of the register to access.
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* @param buffer Memory area to read the data into.
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* @param length The number of bytes to read.
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* @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER or MICROBIT_I2C_ERROR if the magnetometer could not be accessed.
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*/
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int readCommand(uint8_t reg, uint8_t* buffer, int length);
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/**
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* Issues a read of a given address, and returns the value.
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* Blocks the calling thread until complete.
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*
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* @param reg The based address of the 16 bit register to access.
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* @return The register value, interpreted as a 16 but signed value, or MICROBIT_I2C_ERROR if the magnetometer could not be accessed.
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*/
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int read16(uint8_t reg);
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/**
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* Issues a read of a given address, and returns the value.
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* Blocks the calling thread until complete.
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*
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* @param reg The based address of the 16 bit register to access.
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* @return The register value, interpreted as a 8 bit unsigned value, or MICROBIT_I2C_ERROR if the magnetometer could not be accessed.
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*/
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int read8(uint8_t reg);
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};
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#endif
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