Neil Johnson / microbit-ARMBand

Official Sheffield ARMBand micro:bit program

microbit/microbit-dal/source/drivers/MicroBitAccelerometer.cpp@0:b9164b348919, 2016-10-17 (annotated)

Committer:
MrBedfordVan
Date:
Mon Oct 17 12:41:20 2016 +0000
Revision:
0:b9164b348919
Official Sheffield ARMBand Micro:bit program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MrBedfordVan 0:b9164b348919 1 /*
MrBedfordVan 0:b9164b348919 2 The MIT License (MIT)
MrBedfordVan 0:b9164b348919 3
MrBedfordVan 0:b9164b348919 4 Copyright (c) 2016 British Broadcasting Corporation.
MrBedfordVan 0:b9164b348919 5 This software is provided by Lancaster University by arrangement with the BBC.
MrBedfordVan 0:b9164b348919 6
MrBedfordVan 0:b9164b348919 7 Permission is hereby granted, free of charge, to any person obtaining a
MrBedfordVan 0:b9164b348919 8 copy of this software and associated documentation files (the "Software"),
MrBedfordVan 0:b9164b348919 9 to deal in the Software without restriction, including without limitation
MrBedfordVan 0:b9164b348919 10 the rights to use, copy, modify, merge, publish, distribute, sublicense,
MrBedfordVan 0:b9164b348919 11 and/or sell copies of the Software, and to permit persons to whom the
MrBedfordVan 0:b9164b348919 12 Software is furnished to do so, subject to the following conditions:
MrBedfordVan 0:b9164b348919 13
MrBedfordVan 0:b9164b348919 14 The above copyright notice and this permission notice shall be included in
MrBedfordVan 0:b9164b348919 15 all copies or substantial portions of the Software.
MrBedfordVan 0:b9164b348919 16
MrBedfordVan 0:b9164b348919 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
MrBedfordVan 0:b9164b348919 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
MrBedfordVan 0:b9164b348919 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
MrBedfordVan 0:b9164b348919 20 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
MrBedfordVan 0:b9164b348919 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
MrBedfordVan 0:b9164b348919 22 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
MrBedfordVan 0:b9164b348919 23 DEALINGS IN THE SOFTWARE.
MrBedfordVan 0:b9164b348919 24 */
MrBedfordVan 0:b9164b348919 25
MrBedfordVan 0:b9164b348919 26 /**
MrBedfordVan 0:b9164b348919 27 * Class definition for MicroBit Accelerometer.
MrBedfordVan 0:b9164b348919 28 *
MrBedfordVan 0:b9164b348919 29 * Represents an implementation of the Freescale MMA8653 3 axis accelerometer
MrBedfordVan 0:b9164b348919 30 * Also includes basic data caching and on demand activation.
MrBedfordVan 0:b9164b348919 31 */
MrBedfordVan 0:b9164b348919 32 #include "MicroBitConfig.h"
MrBedfordVan 0:b9164b348919 33 #include "MicroBitAccelerometer.h"
MrBedfordVan 0:b9164b348919 34 #include "ErrorNo.h"
MrBedfordVan 0:b9164b348919 35 #include "MicroBitConfig.h"
MrBedfordVan 0:b9164b348919 36 #include "MicroBitEvent.h"
MrBedfordVan 0:b9164b348919 37 #include "MicroBitCompat.h"
MrBedfordVan 0:b9164b348919 38 #include "MicroBitFiber.h"
MrBedfordVan 0:b9164b348919 39
MrBedfordVan 0:b9164b348919 40 /**
MrBedfordVan 0:b9164b348919 41 * Configures the accelerometer for G range and sample rate defined
MrBedfordVan 0:b9164b348919 42 * in this object. The nearest values are chosen to those defined
MrBedfordVan 0:b9164b348919 43 * that are supported by the hardware. The instance variables are then
MrBedfordVan 0:b9164b348919 44 * updated to reflect reality.
MrBedfordVan 0:b9164b348919 45 *
MrBedfordVan 0:b9164b348919 46 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if the accelerometer could not be configured.
MrBedfordVan 0:b9164b348919 47 */
MrBedfordVan 0:b9164b348919 48 int MicroBitAccelerometer::configure()
MrBedfordVan 0:b9164b348919 49 {
MrBedfordVan 0:b9164b348919 50 const MMA8653SampleRangeConfig *actualSampleRange;
MrBedfordVan 0:b9164b348919 51 const MMA8653SampleRateConfig *actualSampleRate;
MrBedfordVan 0:b9164b348919 52 int result;
MrBedfordVan 0:b9164b348919 53
MrBedfordVan 0:b9164b348919 54 // First find the nearest sample rate to that specified.
MrBedfordVan 0:b9164b348919 55 actualSampleRate = &MMA8653SampleRate[MMA8653_SAMPLE_RATES-1];
MrBedfordVan 0:b9164b348919 56 for (int i=MMA8653_SAMPLE_RATES-1; i>=0; i--)
MrBedfordVan 0:b9164b348919 57 {
MrBedfordVan 0:b9164b348919 58 if(MMA8653SampleRate[i].sample_period < this->samplePeriod * 1000)
MrBedfordVan 0:b9164b348919 59 break;
MrBedfordVan 0:b9164b348919 60
MrBedfordVan 0:b9164b348919 61 actualSampleRate = &MMA8653SampleRate[i];
MrBedfordVan 0:b9164b348919 62 }
MrBedfordVan 0:b9164b348919 63
MrBedfordVan 0:b9164b348919 64 // Now find the nearest sample range to that specified.
MrBedfordVan 0:b9164b348919 65 actualSampleRange = &MMA8653SampleRange[MMA8653_SAMPLE_RANGES-1];
MrBedfordVan 0:b9164b348919 66 for (int i=MMA8653_SAMPLE_RANGES-1; i>=0; i--)
MrBedfordVan 0:b9164b348919 67 {
MrBedfordVan 0:b9164b348919 68 if(MMA8653SampleRange[i].sample_range < this->sampleRange)
MrBedfordVan 0:b9164b348919 69 break;
MrBedfordVan 0:b9164b348919 70
MrBedfordVan 0:b9164b348919 71 actualSampleRange = &MMA8653SampleRange[i];
MrBedfordVan 0:b9164b348919 72 }
MrBedfordVan 0:b9164b348919 73
MrBedfordVan 0:b9164b348919 74 // OK, we have the correct data. Update our local state.
MrBedfordVan 0:b9164b348919 75 this->samplePeriod = actualSampleRate->sample_period / 1000;
MrBedfordVan 0:b9164b348919 76 this->sampleRange = actualSampleRange->sample_range;
MrBedfordVan 0:b9164b348919 77
MrBedfordVan 0:b9164b348919 78 // Now configure the accelerometer accordingly.
MrBedfordVan 0:b9164b348919 79 // First place the device into standby mode, so it can be configured.
MrBedfordVan 0:b9164b348919 80 result = writeCommand(MMA8653_CTRL_REG1, 0x00);
MrBedfordVan 0:b9164b348919 81 if (result != 0)
MrBedfordVan 0:b9164b348919 82 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 83
MrBedfordVan 0:b9164b348919 84 // Enable high precisiosn mode. This consumes a bit more power, but still only 184 uA!
MrBedfordVan 0:b9164b348919 85 result = writeCommand(MMA8653_CTRL_REG2, 0x10);
MrBedfordVan 0:b9164b348919 86 if (result != 0)
MrBedfordVan 0:b9164b348919 87 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 88
MrBedfordVan 0:b9164b348919 89 // Enable the INT1 interrupt pin.
MrBedfordVan 0:b9164b348919 90 result = writeCommand(MMA8653_CTRL_REG4, 0x01);
MrBedfordVan 0:b9164b348919 91 if (result != 0)
MrBedfordVan 0:b9164b348919 92 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 93
MrBedfordVan 0:b9164b348919 94 // Select the DATA_READY event source to be routed to INT1
MrBedfordVan 0:b9164b348919 95 result = writeCommand(MMA8653_CTRL_REG5, 0x01);
MrBedfordVan 0:b9164b348919 96 if (result != 0)
MrBedfordVan 0:b9164b348919 97 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 98
MrBedfordVan 0:b9164b348919 99 // Configure for the selected g range.
MrBedfordVan 0:b9164b348919 100 result = writeCommand(MMA8653_XYZ_DATA_CFG, actualSampleRange->xyz_data_cfg);
MrBedfordVan 0:b9164b348919 101 if (result != 0)
MrBedfordVan 0:b9164b348919 102 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 103
MrBedfordVan 0:b9164b348919 104 // Bring the device back online, with 10bit wide samples at the requested frequency.
MrBedfordVan 0:b9164b348919 105 result = writeCommand(MMA8653_CTRL_REG1, actualSampleRate->ctrl_reg1 | 0x01);
MrBedfordVan 0:b9164b348919 106 if (result != 0)
MrBedfordVan 0:b9164b348919 107 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 108
MrBedfordVan 0:b9164b348919 109 return MICROBIT_OK;
MrBedfordVan 0:b9164b348919 110 }
MrBedfordVan 0:b9164b348919 111
MrBedfordVan 0:b9164b348919 112 /**
MrBedfordVan 0:b9164b348919 113 * Issues a standard, 2 byte I2C command write to the accelerometer.
MrBedfordVan 0:b9164b348919 114 *
MrBedfordVan 0:b9164b348919 115 * Blocks the calling thread until complete.
MrBedfordVan 0:b9164b348919 116 *
MrBedfordVan 0:b9164b348919 117 * @param reg The address of the register to write to.
MrBedfordVan 0:b9164b348919 118 *
MrBedfordVan 0:b9164b348919 119 * @param value The value to write.
MrBedfordVan 0:b9164b348919 120 *
MrBedfordVan 0:b9164b348919 121 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if the the write request failed.
MrBedfordVan 0:b9164b348919 122 */
MrBedfordVan 0:b9164b348919 123 int MicroBitAccelerometer::writeCommand(uint8_t reg, uint8_t value)
MrBedfordVan 0:b9164b348919 124 {
MrBedfordVan 0:b9164b348919 125 uint8_t command[2];
MrBedfordVan 0:b9164b348919 126 command[0] = reg;
MrBedfordVan 0:b9164b348919 127 command[1] = value;
MrBedfordVan 0:b9164b348919 128
MrBedfordVan 0:b9164b348919 129 return i2c.write(address, (const char *)command, 2);
MrBedfordVan 0:b9164b348919 130 }
MrBedfordVan 0:b9164b348919 131
MrBedfordVan 0:b9164b348919 132 /**
MrBedfordVan 0:b9164b348919 133 * Issues a read command, copying data into the specified buffer.
MrBedfordVan 0:b9164b348919 134 *
MrBedfordVan 0:b9164b348919 135 * Blocks the calling thread until complete.
MrBedfordVan 0:b9164b348919 136 *
MrBedfordVan 0:b9164b348919 137 * @param reg The address of the register to access.
MrBedfordVan 0:b9164b348919 138 *
MrBedfordVan 0:b9164b348919 139 * @param buffer Memory area to read the data into.
MrBedfordVan 0:b9164b348919 140 *
MrBedfordVan 0:b9164b348919 141 * @param length The number of bytes to read.
MrBedfordVan 0:b9164b348919 142 *
MrBedfordVan 0:b9164b348919 143 * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER or MICROBIT_I2C_ERROR if the the read request failed.
MrBedfordVan 0:b9164b348919 144 */
MrBedfordVan 0:b9164b348919 145 int MicroBitAccelerometer::readCommand(uint8_t reg, uint8_t* buffer, int length)
MrBedfordVan 0:b9164b348919 146 {
MrBedfordVan 0:b9164b348919 147 int result;
MrBedfordVan 0:b9164b348919 148
MrBedfordVan 0:b9164b348919 149 if (buffer == NULL || length <= 0 )
MrBedfordVan 0:b9164b348919 150 return MICROBIT_INVALID_PARAMETER;
MrBedfordVan 0:b9164b348919 151
MrBedfordVan 0:b9164b348919 152 result = i2c.write(address, (const char *)&reg, 1, true);
MrBedfordVan 0:b9164b348919 153 if (result !=0)
MrBedfordVan 0:b9164b348919 154 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 155
MrBedfordVan 0:b9164b348919 156 result = i2c.read(address, (char *)buffer, length);
MrBedfordVan 0:b9164b348919 157 if (result !=0)
MrBedfordVan 0:b9164b348919 158 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 159
MrBedfordVan 0:b9164b348919 160 return MICROBIT_OK;
MrBedfordVan 0:b9164b348919 161 }
MrBedfordVan 0:b9164b348919 162
MrBedfordVan 0:b9164b348919 163 /**
MrBedfordVan 0:b9164b348919 164 * Constructor.
MrBedfordVan 0:b9164b348919 165 * Create a software abstraction of an accelerometer.
MrBedfordVan 0:b9164b348919 166 *
MrBedfordVan 0:b9164b348919 167 * @param _i2c an instance of MicroBitI2C used to communicate with the onboard accelerometer.
MrBedfordVan 0:b9164b348919 168 *
MrBedfordVan 0:b9164b348919 169 * @param address the default I2C address of the accelerometer. Defaults to: MMA8653_DEFAULT_ADDR.
MrBedfordVan 0:b9164b348919 170 *
MrBedfordVan 0:b9164b348919 171 * @param id the unique EventModel id of this component. Defaults to: MICROBIT_ID_ACCELEROMETER
MrBedfordVan 0:b9164b348919 172 *
MrBedfordVan 0:b9164b348919 173 * @code
MrBedfordVan 0:b9164b348919 174 * MicroBitI2C i2c = MicroBitI2C(I2C_SDA0, I2C_SCL0);
MrBedfordVan 0:b9164b348919 175 *
MrBedfordVan 0:b9164b348919 176 * MicroBitAccelerometer accelerometer = MicroBitAccelerometer(i2c);
MrBedfordVan 0:b9164b348919 177 * @endcode
MrBedfordVan 0:b9164b348919 178 */
MrBedfordVan 0:b9164b348919 179 MicroBitAccelerometer::MicroBitAccelerometer(MicroBitI2C& _i2c, uint16_t address, uint16_t id) : sample(), int1(MICROBIT_PIN_ACCEL_DATA_READY), i2c(_i2c)
MrBedfordVan 0:b9164b348919 180 {
MrBedfordVan 0:b9164b348919 181 // Store our identifiers.
MrBedfordVan 0:b9164b348919 182 this->id = id;
MrBedfordVan 0:b9164b348919 183 this->status = 0;
MrBedfordVan 0:b9164b348919 184 this->address = address;
MrBedfordVan 0:b9164b348919 185
MrBedfordVan 0:b9164b348919 186 // Update our internal state for 50Hz at +/- 2g (50Hz has a period af 20ms).
MrBedfordVan 0:b9164b348919 187 this->samplePeriod = 20;
MrBedfordVan 0:b9164b348919 188 this->sampleRange = 2;
MrBedfordVan 0:b9164b348919 189
MrBedfordVan 0:b9164b348919 190 // Initialise gesture history
MrBedfordVan 0:b9164b348919 191 this->sigma = 0;
MrBedfordVan 0:b9164b348919 192 this->impulseSigma = 0;
MrBedfordVan 0:b9164b348919 193 this->lastGesture = MICROBIT_ACCELEROMETER_EVT_NONE;
MrBedfordVan 0:b9164b348919 194 this->currentGesture = MICROBIT_ACCELEROMETER_EVT_NONE;
MrBedfordVan 0:b9164b348919 195 this->shake.x = 0;
MrBedfordVan 0:b9164b348919 196 this->shake.y = 0;
MrBedfordVan 0:b9164b348919 197 this->shake.z = 0;
MrBedfordVan 0:b9164b348919 198 this->shake.count = 0;
MrBedfordVan 0:b9164b348919 199 this->shake.timer = 0;
MrBedfordVan 0:b9164b348919 200 this->shake.impulse_3 = 1;
MrBedfordVan 0:b9164b348919 201 this->shake.impulse_6 = 1;
MrBedfordVan 0:b9164b348919 202 this->shake.impulse_8 = 1;
MrBedfordVan 0:b9164b348919 203
MrBedfordVan 0:b9164b348919 204 // Configure and enable the accelerometer.
MrBedfordVan 0:b9164b348919 205 if (this->configure() == MICROBIT_OK)
MrBedfordVan 0:b9164b348919 206 status |= MICROBIT_COMPONENT_RUNNING;
MrBedfordVan 0:b9164b348919 207 }
MrBedfordVan 0:b9164b348919 208
MrBedfordVan 0:b9164b348919 209 /**
MrBedfordVan 0:b9164b348919 210 * Attempts to read the 8 bit ID from the accelerometer, this can be used for
MrBedfordVan 0:b9164b348919 211 * validation purposes.
MrBedfordVan 0:b9164b348919 212 *
MrBedfordVan 0:b9164b348919 213 * @return the 8 bit ID returned by the accelerometer, or MICROBIT_I2C_ERROR if the request fails.
MrBedfordVan 0:b9164b348919 214 *
MrBedfordVan 0:b9164b348919 215 * @code
MrBedfordVan 0:b9164b348919 216 * accelerometer.whoAmI();
MrBedfordVan 0:b9164b348919 217 * @endcode
MrBedfordVan 0:b9164b348919 218 */
MrBedfordVan 0:b9164b348919 219 int MicroBitAccelerometer::whoAmI()
MrBedfordVan 0:b9164b348919 220 {
MrBedfordVan 0:b9164b348919 221 uint8_t data;
MrBedfordVan 0:b9164b348919 222 int result;
MrBedfordVan 0:b9164b348919 223
MrBedfordVan 0:b9164b348919 224 result = readCommand(MMA8653_WHOAMI, &data, 1);
MrBedfordVan 0:b9164b348919 225 if (result !=0)
MrBedfordVan 0:b9164b348919 226 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 227
MrBedfordVan 0:b9164b348919 228 return (int)data;
MrBedfordVan 0:b9164b348919 229 }
MrBedfordVan 0:b9164b348919 230
MrBedfordVan 0:b9164b348919 231 /**
MrBedfordVan 0:b9164b348919 232 * Reads the acceleration data from the accelerometer, and stores it in our buffer.
MrBedfordVan 0:b9164b348919 233 * This only happens if the accelerometer indicates that it has new data via int1.
MrBedfordVan 0:b9164b348919 234 *
MrBedfordVan 0:b9164b348919 235 * On first use, this member function will attempt to add this component to the
MrBedfordVan 0:b9164b348919 236 * list of fiber components in order to constantly update the values stored
MrBedfordVan 0:b9164b348919 237 * by this object.
MrBedfordVan 0:b9164b348919 238 *
MrBedfordVan 0:b9164b348919 239 * This technique is called lazy instantiation, and it means that we do not
MrBedfordVan 0:b9164b348919 240 * obtain the overhead from non-chalantly adding this component to fiber components.
MrBedfordVan 0:b9164b348919 241 *
MrBedfordVan 0:b9164b348919 242 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if the read request fails.
MrBedfordVan 0:b9164b348919 243 */
MrBedfordVan 0:b9164b348919 244 int MicroBitAccelerometer::updateSample()
MrBedfordVan 0:b9164b348919 245 {
MrBedfordVan 0:b9164b348919 246 if(!(status & MICROBIT_ACCEL_ADDED_TO_IDLE))
MrBedfordVan 0:b9164b348919 247 {
MrBedfordVan 0:b9164b348919 248 fiber_add_idle_component(this);
MrBedfordVan 0:b9164b348919 249 status |= MICROBIT_ACCEL_ADDED_TO_IDLE;
MrBedfordVan 0:b9164b348919 250 }
MrBedfordVan 0:b9164b348919 251
MrBedfordVan 0:b9164b348919 252 // Poll interrupt line from accelerometer.
MrBedfordVan 0:b9164b348919 253 // n.b. Default is Active LO. Interrupt is cleared in data read.
MrBedfordVan 0:b9164b348919 254 if(!int1)
MrBedfordVan 0:b9164b348919 255 {
MrBedfordVan 0:b9164b348919 256 int8_t data[6];
MrBedfordVan 0:b9164b348919 257 int result;
MrBedfordVan 0:b9164b348919 258
MrBedfordVan 0:b9164b348919 259 result = readCommand(MMA8653_OUT_X_MSB, (uint8_t *)data, 6);
MrBedfordVan 0:b9164b348919 260 if (result !=0)
MrBedfordVan 0:b9164b348919 261 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 262
MrBedfordVan 0:b9164b348919 263 // read MSB values...
MrBedfordVan 0:b9164b348919 264 sample.x = data[0];
MrBedfordVan 0:b9164b348919 265 sample.y = data[2];
MrBedfordVan 0:b9164b348919 266 sample.z = data[4];
MrBedfordVan 0:b9164b348919 267
MrBedfordVan 0:b9164b348919 268 // Normalize the data in the 0..1024 range.
MrBedfordVan 0:b9164b348919 269 sample.x *= 8;
MrBedfordVan 0:b9164b348919 270 sample.y *= 8;
MrBedfordVan 0:b9164b348919 271 sample.z *= 8;
MrBedfordVan 0:b9164b348919 272
MrBedfordVan 0:b9164b348919 273 #if CONFIG_ENABLED(USE_ACCEL_LSB)
MrBedfordVan 0:b9164b348919 274 // Add in LSB values.
MrBedfordVan 0:b9164b348919 275 sample.x += (data[1] / 64);
MrBedfordVan 0:b9164b348919 276 sample.y += (data[3] / 64);
MrBedfordVan 0:b9164b348919 277 sample.z += (data[5] / 64);
MrBedfordVan 0:b9164b348919 278 #endif
MrBedfordVan 0:b9164b348919 279
MrBedfordVan 0:b9164b348919 280 // Scale into millig (approx!)
MrBedfordVan 0:b9164b348919 281 sample.x *= this->sampleRange;
MrBedfordVan 0:b9164b348919 282 sample.y *= this->sampleRange;
MrBedfordVan 0:b9164b348919 283 sample.z *= this->sampleRange;
MrBedfordVan 0:b9164b348919 284
MrBedfordVan 0:b9164b348919 285 // Indicate that pitch and roll data is now stale, and needs to be recalculated if needed.
MrBedfordVan 0:b9164b348919 286 status &= ~MICROBIT_ACCEL_PITCH_ROLL_VALID;
MrBedfordVan 0:b9164b348919 287
MrBedfordVan 0:b9164b348919 288 // Update gesture tracking
MrBedfordVan 0:b9164b348919 289 updateGesture();
MrBedfordVan 0:b9164b348919 290
MrBedfordVan 0:b9164b348919 291 // Indicate that a new sample is available
MrBedfordVan 0:b9164b348919 292 MicroBitEvent e(id, MICROBIT_ACCELEROMETER_EVT_DATA_UPDATE);
MrBedfordVan 0:b9164b348919 293 }
MrBedfordVan 0:b9164b348919 294
MrBedfordVan 0:b9164b348919 295 return MICROBIT_OK;
MrBedfordVan 0:b9164b348919 296 };
MrBedfordVan 0:b9164b348919 297
MrBedfordVan 0:b9164b348919 298 /**
MrBedfordVan 0:b9164b348919 299 * A service function.
MrBedfordVan 0:b9164b348919 300 * It calculates the current scalar acceleration of the device (x^2 + y^2 + z^2).
MrBedfordVan 0:b9164b348919 301 * It does not, however, square root the result, as this is a relatively high cost operation.
MrBedfordVan 0:b9164b348919 302 *
MrBedfordVan 0:b9164b348919 303 * This is left to application code should it be needed.
MrBedfordVan 0:b9164b348919 304 *
MrBedfordVan 0:b9164b348919 305 * @return the sum of the square of the acceleration of the device across all axes.
MrBedfordVan 0:b9164b348919 306 */
MrBedfordVan 0:b9164b348919 307 int MicroBitAccelerometer::instantaneousAccelerationSquared()
MrBedfordVan 0:b9164b348919 308 {
MrBedfordVan 0:b9164b348919 309 updateSample();
MrBedfordVan 0:b9164b348919 310
MrBedfordVan 0:b9164b348919 311 // Use pythagoras theorem to determine the combined force acting on the device.
MrBedfordVan 0:b9164b348919 312 return (int)sample.x*(int)sample.x + (int)sample.y*(int)sample.y + (int)sample.z*(int)sample.z;
MrBedfordVan 0:b9164b348919 313 }
MrBedfordVan 0:b9164b348919 314
MrBedfordVan 0:b9164b348919 315 /**
MrBedfordVan 0:b9164b348919 316 * Service function.
MrBedfordVan 0:b9164b348919 317 * Determines a 'best guess' posture of the device based on instantaneous data.
MrBedfordVan 0:b9164b348919 318 *
MrBedfordVan 0:b9164b348919 319 * This makes no use of historic data, and forms the input to the filter implemented in updateGesture().
MrBedfordVan 0:b9164b348919 320 *
MrBedfordVan 0:b9164b348919 321 * @return A 'best guess' of the current posture of the device, based on instanataneous data.
MrBedfordVan 0:b9164b348919 322 */
MrBedfordVan 0:b9164b348919 323 uint16_t MicroBitAccelerometer::instantaneousPosture()
MrBedfordVan 0:b9164b348919 324 {
MrBedfordVan 0:b9164b348919 325 bool shakeDetected = false;
MrBedfordVan 0:b9164b348919 326
MrBedfordVan 0:b9164b348919 327 // Test for shake events.
MrBedfordVan 0:b9164b348919 328 // We detect a shake by measuring zero crossings in each axis. In other words, if we see a strong acceleration to the left followed by
MrBedfordVan 0:b9164b348919 329 // a strong acceleration to the right, then we can infer a shake. Similarly, we can do this for each axis (left/right, up/down, in/out).
MrBedfordVan 0:b9164b348919 330 //
MrBedfordVan 0:b9164b348919 331 // If we see enough zero crossings in succession (MICROBIT_ACCELEROMETER_SHAKE_COUNT_THRESHOLD), then we decide that the device
MrBedfordVan 0:b9164b348919 332 // has been shaken.
MrBedfordVan 0:b9164b348919 333 if ((getX() < -MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && shake.x) || (getX() > MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && !shake.x))
MrBedfordVan 0:b9164b348919 334 {
MrBedfordVan 0:b9164b348919 335 shakeDetected = true;
MrBedfordVan 0:b9164b348919 336 shake.x = !shake.x;
MrBedfordVan 0:b9164b348919 337 }
MrBedfordVan 0:b9164b348919 338
MrBedfordVan 0:b9164b348919 339 if ((getY() < -MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && shake.y) || (getY() > MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && !shake.y))
MrBedfordVan 0:b9164b348919 340 {
MrBedfordVan 0:b9164b348919 341 shakeDetected = true;
MrBedfordVan 0:b9164b348919 342 shake.y = !shake.y;
MrBedfordVan 0:b9164b348919 343 }
MrBedfordVan 0:b9164b348919 344
MrBedfordVan 0:b9164b348919 345 if ((getZ() < -MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && shake.z) || (getZ() > MICROBIT_ACCELEROMETER_SHAKE_TOLERANCE && !shake.z))
MrBedfordVan 0:b9164b348919 346 {
MrBedfordVan 0:b9164b348919 347 shakeDetected = true;
MrBedfordVan 0:b9164b348919 348 shake.z = !shake.z;
MrBedfordVan 0:b9164b348919 349 }
MrBedfordVan 0:b9164b348919 350
MrBedfordVan 0:b9164b348919 351 // If we detected a zero crossing in this sample period, count this.
MrBedfordVan 0:b9164b348919 352 if (shakeDetected && shake.count < MICROBIT_ACCELEROMETER_SHAKE_COUNT_THRESHOLD)
MrBedfordVan 0:b9164b348919 353 {
MrBedfordVan 0:b9164b348919 354 shake.count++;
MrBedfordVan 0:b9164b348919 355
MrBedfordVan 0:b9164b348919 356 if (shake.count == 1)
MrBedfordVan 0:b9164b348919 357 shake.timer = 0;
MrBedfordVan 0:b9164b348919 358
MrBedfordVan 0:b9164b348919 359 if (shake.count == MICROBIT_ACCELEROMETER_SHAKE_COUNT_THRESHOLD)
MrBedfordVan 0:b9164b348919 360 {
MrBedfordVan 0:b9164b348919 361 shake.shaken = 1;
MrBedfordVan 0:b9164b348919 362 shake.timer = 0;
MrBedfordVan 0:b9164b348919 363 return MICROBIT_ACCELEROMETER_EVT_SHAKE;
MrBedfordVan 0:b9164b348919 364 }
MrBedfordVan 0:b9164b348919 365 }
MrBedfordVan 0:b9164b348919 366
MrBedfordVan 0:b9164b348919 367 // measure how long we have been detecting a SHAKE event.
MrBedfordVan 0:b9164b348919 368 if (shake.count > 0)
MrBedfordVan 0:b9164b348919 369 {
MrBedfordVan 0:b9164b348919 370 shake.timer++;
MrBedfordVan 0:b9164b348919 371
MrBedfordVan 0:b9164b348919 372 // If we've issued a SHAKE event already, and sufficient time has assed, allow another SHAKE event to be issued.
MrBedfordVan 0:b9164b348919 373 if (shake.shaken && shake.timer >= MICROBIT_ACCELEROMETER_SHAKE_RTX)
MrBedfordVan 0:b9164b348919 374 {
MrBedfordVan 0:b9164b348919 375 shake.shaken = 0;
MrBedfordVan 0:b9164b348919 376 shake.timer = 0;
MrBedfordVan 0:b9164b348919 377 shake.count = 0;
MrBedfordVan 0:b9164b348919 378 }
MrBedfordVan 0:b9164b348919 379
MrBedfordVan 0:b9164b348919 380 // Decay our count of zero crossings over time. We don't want them to accumulate if the user performs slow moving motions.
MrBedfordVan 0:b9164b348919 381 else if (!shake.shaken && shake.timer >= MICROBIT_ACCELEROMETER_SHAKE_DAMPING)
MrBedfordVan 0:b9164b348919 382 {
MrBedfordVan 0:b9164b348919 383 shake.timer = 0;
MrBedfordVan 0:b9164b348919 384 if (shake.count > 0)
MrBedfordVan 0:b9164b348919 385 shake.count--;
MrBedfordVan 0:b9164b348919 386 }
MrBedfordVan 0:b9164b348919 387 }
MrBedfordVan 0:b9164b348919 388
MrBedfordVan 0:b9164b348919 389 if (instantaneousAccelerationSquared() < MICROBIT_ACCELEROMETER_FREEFALL_THRESHOLD)
MrBedfordVan 0:b9164b348919 390 return MICROBIT_ACCELEROMETER_EVT_FREEFALL;
MrBedfordVan 0:b9164b348919 391
MrBedfordVan 0:b9164b348919 392 // Determine our posture.
MrBedfordVan 0:b9164b348919 393 if (getX() < (-1000 + MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 394 return MICROBIT_ACCELEROMETER_EVT_TILT_LEFT;
MrBedfordVan 0:b9164b348919 395
MrBedfordVan 0:b9164b348919 396 if (getX() > (1000 - MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 397 return MICROBIT_ACCELEROMETER_EVT_TILT_RIGHT;
MrBedfordVan 0:b9164b348919 398
MrBedfordVan 0:b9164b348919 399 if (getY() < (-1000 + MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 400 return MICROBIT_ACCELEROMETER_EVT_TILT_DOWN;
MrBedfordVan 0:b9164b348919 401
MrBedfordVan 0:b9164b348919 402 if (getY() > (1000 - MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 403 return MICROBIT_ACCELEROMETER_EVT_TILT_UP;
MrBedfordVan 0:b9164b348919 404
MrBedfordVan 0:b9164b348919 405 if (getZ() < (-1000 + MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 406 return MICROBIT_ACCELEROMETER_EVT_FACE_UP;
MrBedfordVan 0:b9164b348919 407
MrBedfordVan 0:b9164b348919 408 if (getZ() > (1000 - MICROBIT_ACCELEROMETER_TILT_TOLERANCE))
MrBedfordVan 0:b9164b348919 409 return MICROBIT_ACCELEROMETER_EVT_FACE_DOWN;
MrBedfordVan 0:b9164b348919 410
MrBedfordVan 0:b9164b348919 411 return MICROBIT_ACCELEROMETER_EVT_NONE;
MrBedfordVan 0:b9164b348919 412 }
MrBedfordVan 0:b9164b348919 413
MrBedfordVan 0:b9164b348919 414 /**
MrBedfordVan 0:b9164b348919 415 * Updates the basic gesture recognizer. This performs instantaneous pose recognition, and also some low pass filtering to promote
MrBedfordVan 0:b9164b348919 416 * stability.
MrBedfordVan 0:b9164b348919 417 */
MrBedfordVan 0:b9164b348919 418 void MicroBitAccelerometer::updateGesture()
MrBedfordVan 0:b9164b348919 419 {
MrBedfordVan 0:b9164b348919 420 // Check for High/Low G force events - typically impulses, impacts etc.
MrBedfordVan 0:b9164b348919 421 // Again, during such spikes, these event take priority of the posture of the device.
MrBedfordVan 0:b9164b348919 422 // For these events, we don't perform any low pass filtering.
MrBedfordVan 0:b9164b348919 423 int force = instantaneousAccelerationSquared();
MrBedfordVan 0:b9164b348919 424
MrBedfordVan 0:b9164b348919 425 if (force > MICROBIT_ACCELEROMETER_3G_THRESHOLD)
MrBedfordVan 0:b9164b348919 426 {
MrBedfordVan 0:b9164b348919 427 if (force > MICROBIT_ACCELEROMETER_3G_THRESHOLD && !shake.impulse_3)
MrBedfordVan 0:b9164b348919 428 {
MrBedfordVan 0:b9164b348919 429 MicroBitEvent e(MICROBIT_ID_GESTURE, MICROBIT_ACCELEROMETER_EVT_3G);
MrBedfordVan 0:b9164b348919 430 shake.impulse_3 = 1;
MrBedfordVan 0:b9164b348919 431 }
MrBedfordVan 0:b9164b348919 432 if (force > MICROBIT_ACCELEROMETER_6G_THRESHOLD && !shake.impulse_6)
MrBedfordVan 0:b9164b348919 433 {
MrBedfordVan 0:b9164b348919 434 MicroBitEvent e(MICROBIT_ID_GESTURE, MICROBIT_ACCELEROMETER_EVT_6G);
MrBedfordVan 0:b9164b348919 435 shake.impulse_6 = 1;
MrBedfordVan 0:b9164b348919 436 }
MrBedfordVan 0:b9164b348919 437 if (force > MICROBIT_ACCELEROMETER_8G_THRESHOLD && !shake.impulse_8)
MrBedfordVan 0:b9164b348919 438 {
MrBedfordVan 0:b9164b348919 439 MicroBitEvent e(MICROBIT_ID_GESTURE, MICROBIT_ACCELEROMETER_EVT_8G);
MrBedfordVan 0:b9164b348919 440 shake.impulse_8 = 1;
MrBedfordVan 0:b9164b348919 441 }
MrBedfordVan 0:b9164b348919 442
MrBedfordVan 0:b9164b348919 443 impulseSigma = 0;
MrBedfordVan 0:b9164b348919 444 }
MrBedfordVan 0:b9164b348919 445
MrBedfordVan 0:b9164b348919 446 // Reset the impulse event onve the acceleration has subsided.
MrBedfordVan 0:b9164b348919 447 if (impulseSigma < MICROBIT_ACCELEROMETER_GESTURE_DAMPING)
MrBedfordVan 0:b9164b348919 448 impulseSigma++;
MrBedfordVan 0:b9164b348919 449 else
MrBedfordVan 0:b9164b348919 450 shake.impulse_3 = shake.impulse_6 = shake.impulse_8 = 0;
MrBedfordVan 0:b9164b348919 451
MrBedfordVan 0:b9164b348919 452
MrBedfordVan 0:b9164b348919 453 // Determine what it looks like we're doing based on the latest sample...
MrBedfordVan 0:b9164b348919 454 uint16_t g = instantaneousPosture();
MrBedfordVan 0:b9164b348919 455
MrBedfordVan 0:b9164b348919 456 if (g == MICROBIT_ACCELEROMETER_EVT_SHAKE)
MrBedfordVan 0:b9164b348919 457 {
MrBedfordVan 0:b9164b348919 458 MicroBitEvent e(MICROBIT_ID_GESTURE, MICROBIT_ACCELEROMETER_EVT_SHAKE);
MrBedfordVan 0:b9164b348919 459 return;
MrBedfordVan 0:b9164b348919 460 }
MrBedfordVan 0:b9164b348919 461
MrBedfordVan 0:b9164b348919 462 // Perform some low pass filtering to reduce jitter from any detected effects
MrBedfordVan 0:b9164b348919 463 if (g == currentGesture)
MrBedfordVan 0:b9164b348919 464 {
MrBedfordVan 0:b9164b348919 465 if (sigma < MICROBIT_ACCELEROMETER_GESTURE_DAMPING)
MrBedfordVan 0:b9164b348919 466 sigma++;
MrBedfordVan 0:b9164b348919 467 }
MrBedfordVan 0:b9164b348919 468 else
MrBedfordVan 0:b9164b348919 469 {
MrBedfordVan 0:b9164b348919 470 currentGesture = g;
MrBedfordVan 0:b9164b348919 471 sigma = 0;
MrBedfordVan 0:b9164b348919 472 }
MrBedfordVan 0:b9164b348919 473
MrBedfordVan 0:b9164b348919 474 // If we've reached threshold, update our record and raise the relevant event...
MrBedfordVan 0:b9164b348919 475 if (currentGesture != lastGesture && sigma >= MICROBIT_ACCELEROMETER_GESTURE_DAMPING)
MrBedfordVan 0:b9164b348919 476 {
MrBedfordVan 0:b9164b348919 477 lastGesture = currentGesture;
MrBedfordVan 0:b9164b348919 478 MicroBitEvent e(MICROBIT_ID_GESTURE, lastGesture);
MrBedfordVan 0:b9164b348919 479 }
MrBedfordVan 0:b9164b348919 480 }
MrBedfordVan 0:b9164b348919 481
MrBedfordVan 0:b9164b348919 482 /**
MrBedfordVan 0:b9164b348919 483 * Attempts to set the sample rate of the accelerometer to the specified value (in ms).
MrBedfordVan 0:b9164b348919 484 *
MrBedfordVan 0:b9164b348919 485 * @param period the requested time between samples, in milliseconds.
MrBedfordVan 0:b9164b348919 486 *
MrBedfordVan 0:b9164b348919 487 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR is the request fails.
MrBedfordVan 0:b9164b348919 488 *
MrBedfordVan 0:b9164b348919 489 * @code
MrBedfordVan 0:b9164b348919 490 * // sample rate is now 20 ms.
MrBedfordVan 0:b9164b348919 491 * accelerometer.setPeriod(20);
MrBedfordVan 0:b9164b348919 492 * @endcode
MrBedfordVan 0:b9164b348919 493 *
MrBedfordVan 0:b9164b348919 494 * @note The requested rate may not be possible on the hardware. In this case, the
MrBedfordVan 0:b9164b348919 495 * nearest lower rate is chosen.
MrBedfordVan 0:b9164b348919 496 */
MrBedfordVan 0:b9164b348919 497 int MicroBitAccelerometer::setPeriod(int period)
MrBedfordVan 0:b9164b348919 498 {
MrBedfordVan 0:b9164b348919 499 this->samplePeriod = period;
MrBedfordVan 0:b9164b348919 500 return this->configure();
MrBedfordVan 0:b9164b348919 501 }
MrBedfordVan 0:b9164b348919 502
MrBedfordVan 0:b9164b348919 503 /**
MrBedfordVan 0:b9164b348919 504 * Reads the currently configured sample rate of the accelerometer.
MrBedfordVan 0:b9164b348919 505 *
MrBedfordVan 0:b9164b348919 506 * @return The time between samples, in milliseconds.
MrBedfordVan 0:b9164b348919 507 */
MrBedfordVan 0:b9164b348919 508 int MicroBitAccelerometer::getPeriod()
MrBedfordVan 0:b9164b348919 509 {
MrBedfordVan 0:b9164b348919 510 return (int)samplePeriod;
MrBedfordVan 0:b9164b348919 511 }
MrBedfordVan 0:b9164b348919 512
MrBedfordVan 0:b9164b348919 513 /**
MrBedfordVan 0:b9164b348919 514 * Attempts to set the sample range of the accelerometer to the specified value (in g).
MrBedfordVan 0:b9164b348919 515 *
MrBedfordVan 0:b9164b348919 516 * @param range The requested sample range of samples, in g.
MrBedfordVan 0:b9164b348919 517 *
MrBedfordVan 0:b9164b348919 518 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR is the request fails.
MrBedfordVan 0:b9164b348919 519 *
MrBedfordVan 0:b9164b348919 520 * @code
MrBedfordVan 0:b9164b348919 521 * // the sample range of the accelerometer is now 8G.
MrBedfordVan 0:b9164b348919 522 * accelerometer.setRange(8);
MrBedfordVan 0:b9164b348919 523 * @endcode
MrBedfordVan 0:b9164b348919 524 *
MrBedfordVan 0:b9164b348919 525 * @note The requested range may not be possible on the hardware. In this case, the
MrBedfordVan 0:b9164b348919 526 * nearest lower range is chosen.
MrBedfordVan 0:b9164b348919 527 */
MrBedfordVan 0:b9164b348919 528 int MicroBitAccelerometer::setRange(int range)
MrBedfordVan 0:b9164b348919 529 {
MrBedfordVan 0:b9164b348919 530 this->sampleRange = range;
MrBedfordVan 0:b9164b348919 531 return this->configure();
MrBedfordVan 0:b9164b348919 532 }
MrBedfordVan 0:b9164b348919 533
MrBedfordVan 0:b9164b348919 534 /**
MrBedfordVan 0:b9164b348919 535 * Reads the currently configured sample range of the accelerometer.
MrBedfordVan 0:b9164b348919 536 *
MrBedfordVan 0:b9164b348919 537 * @return The sample range, in g.
MrBedfordVan 0:b9164b348919 538 */
MrBedfordVan 0:b9164b348919 539 int MicroBitAccelerometer::getRange()
MrBedfordVan 0:b9164b348919 540 {
MrBedfordVan 0:b9164b348919 541 return (int)sampleRange;
MrBedfordVan 0:b9164b348919 542 }
MrBedfordVan 0:b9164b348919 543
MrBedfordVan 0:b9164b348919 544 /**
MrBedfordVan 0:b9164b348919 545 * Reads the value of the X axis from the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 546 *
MrBedfordVan 0:b9164b348919 547 * @param system The coordinate system to use. By default, a simple cartesian system is provided.
MrBedfordVan 0:b9164b348919 548 *
MrBedfordVan 0:b9164b348919 549 * @return The force measured in the X axis, in milli-g.
MrBedfordVan 0:b9164b348919 550 *
MrBedfordVan 0:b9164b348919 551 * @code
MrBedfordVan 0:b9164b348919 552 * accelerometer.getX();
MrBedfordVan 0:b9164b348919 553 * @endcode
MrBedfordVan 0:b9164b348919 554 */
MrBedfordVan 0:b9164b348919 555 int MicroBitAccelerometer::getX(MicroBitCoordinateSystem system)
MrBedfordVan 0:b9164b348919 556 {
MrBedfordVan 0:b9164b348919 557 updateSample();
MrBedfordVan 0:b9164b348919 558
MrBedfordVan 0:b9164b348919 559 switch (system)
MrBedfordVan 0:b9164b348919 560 {
MrBedfordVan 0:b9164b348919 561 case SIMPLE_CARTESIAN:
MrBedfordVan 0:b9164b348919 562 return -sample.x;
MrBedfordVan 0:b9164b348919 563
MrBedfordVan 0:b9164b348919 564 case NORTH_EAST_DOWN:
MrBedfordVan 0:b9164b348919 565 return sample.y;
MrBedfordVan 0:b9164b348919 566
MrBedfordVan 0:b9164b348919 567 case RAW:
MrBedfordVan 0:b9164b348919 568 default:
MrBedfordVan 0:b9164b348919 569 return sample.x;
MrBedfordVan 0:b9164b348919 570 }
MrBedfordVan 0:b9164b348919 571 }
MrBedfordVan 0:b9164b348919 572
MrBedfordVan 0:b9164b348919 573 /**
MrBedfordVan 0:b9164b348919 574 * Reads the value of the Y axis from the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 575 *
MrBedfordVan 0:b9164b348919 576 * @return The force measured in the Y axis, in milli-g.
MrBedfordVan 0:b9164b348919 577 *
MrBedfordVan 0:b9164b348919 578 * @code
MrBedfordVan 0:b9164b348919 579 * accelerometer.getY();
MrBedfordVan 0:b9164b348919 580 * @endcode
MrBedfordVan 0:b9164b348919 581 */
MrBedfordVan 0:b9164b348919 582 int MicroBitAccelerometer::getY(MicroBitCoordinateSystem system)
MrBedfordVan 0:b9164b348919 583 {
MrBedfordVan 0:b9164b348919 584 updateSample();
MrBedfordVan 0:b9164b348919 585
MrBedfordVan 0:b9164b348919 586 switch (system)
MrBedfordVan 0:b9164b348919 587 {
MrBedfordVan 0:b9164b348919 588 case SIMPLE_CARTESIAN:
MrBedfordVan 0:b9164b348919 589 return -sample.y;
MrBedfordVan 0:b9164b348919 590
MrBedfordVan 0:b9164b348919 591 case NORTH_EAST_DOWN:
MrBedfordVan 0:b9164b348919 592 return -sample.x;
MrBedfordVan 0:b9164b348919 593
MrBedfordVan 0:b9164b348919 594 case RAW:
MrBedfordVan 0:b9164b348919 595 default:
MrBedfordVan 0:b9164b348919 596 return sample.y;
MrBedfordVan 0:b9164b348919 597 }
MrBedfordVan 0:b9164b348919 598 }
MrBedfordVan 0:b9164b348919 599
MrBedfordVan 0:b9164b348919 600 /**
MrBedfordVan 0:b9164b348919 601 * Reads the value of the Z axis from the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 602 *
MrBedfordVan 0:b9164b348919 603 * @return The force measured in the Z axis, in milli-g.
MrBedfordVan 0:b9164b348919 604 *
MrBedfordVan 0:b9164b348919 605 * @code
MrBedfordVan 0:b9164b348919 606 * accelerometer.getZ();
MrBedfordVan 0:b9164b348919 607 * @endcode
MrBedfordVan 0:b9164b348919 608 */
MrBedfordVan 0:b9164b348919 609 int MicroBitAccelerometer::getZ(MicroBitCoordinateSystem system)
MrBedfordVan 0:b9164b348919 610 {
MrBedfordVan 0:b9164b348919 611 updateSample();
MrBedfordVan 0:b9164b348919 612
MrBedfordVan 0:b9164b348919 613 switch (system)
MrBedfordVan 0:b9164b348919 614 {
MrBedfordVan 0:b9164b348919 615 case NORTH_EAST_DOWN:
MrBedfordVan 0:b9164b348919 616 return -sample.z;
MrBedfordVan 0:b9164b348919 617
MrBedfordVan 0:b9164b348919 618 case SIMPLE_CARTESIAN:
MrBedfordVan 0:b9164b348919 619 case RAW:
MrBedfordVan 0:b9164b348919 620 default:
MrBedfordVan 0:b9164b348919 621 return sample.z;
MrBedfordVan 0:b9164b348919 622 }
MrBedfordVan 0:b9164b348919 623 }
MrBedfordVan 0:b9164b348919 624
MrBedfordVan 0:b9164b348919 625 /**
MrBedfordVan 0:b9164b348919 626 * Provides a rotation compensated pitch of the device, based on the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 627 *
MrBedfordVan 0:b9164b348919 628 * @return The pitch of the device, in degrees.
MrBedfordVan 0:b9164b348919 629 *
MrBedfordVan 0:b9164b348919 630 * @code
MrBedfordVan 0:b9164b348919 631 * accelerometer.getPitch();
MrBedfordVan 0:b9164b348919 632 * @endcode
MrBedfordVan 0:b9164b348919 633 */
MrBedfordVan 0:b9164b348919 634 int MicroBitAccelerometer::getPitch()
MrBedfordVan 0:b9164b348919 635 {
MrBedfordVan 0:b9164b348919 636 return (int) ((360*getPitchRadians()) / (2*PI));
MrBedfordVan 0:b9164b348919 637 }
MrBedfordVan 0:b9164b348919 638
MrBedfordVan 0:b9164b348919 639 /**
MrBedfordVan 0:b9164b348919 640 * Provides a rotation compensated pitch of the device, based on the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 641 *
MrBedfordVan 0:b9164b348919 642 * @return The pitch of the device, in radians.
MrBedfordVan 0:b9164b348919 643 *
MrBedfordVan 0:b9164b348919 644 * @code
MrBedfordVan 0:b9164b348919 645 * accelerometer.getPitchRadians();
MrBedfordVan 0:b9164b348919 646 * @endcode
MrBedfordVan 0:b9164b348919 647 */
MrBedfordVan 0:b9164b348919 648 float MicroBitAccelerometer::getPitchRadians()
MrBedfordVan 0:b9164b348919 649 {
MrBedfordVan 0:b9164b348919 650 if (!(status & MICROBIT_ACCEL_PITCH_ROLL_VALID))
MrBedfordVan 0:b9164b348919 651 recalculatePitchRoll();
MrBedfordVan 0:b9164b348919 652
MrBedfordVan 0:b9164b348919 653 return pitch;
MrBedfordVan 0:b9164b348919 654 }
MrBedfordVan 0:b9164b348919 655
MrBedfordVan 0:b9164b348919 656 /**
MrBedfordVan 0:b9164b348919 657 * Provides a rotation compensated roll of the device, based on the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 658 *
MrBedfordVan 0:b9164b348919 659 * @return The roll of the device, in degrees.
MrBedfordVan 0:b9164b348919 660 *
MrBedfordVan 0:b9164b348919 661 * @code
MrBedfordVan 0:b9164b348919 662 * accelerometer.getRoll();
MrBedfordVan 0:b9164b348919 663 * @endcode
MrBedfordVan 0:b9164b348919 664 */
MrBedfordVan 0:b9164b348919 665 int MicroBitAccelerometer::getRoll()
MrBedfordVan 0:b9164b348919 666 {
MrBedfordVan 0:b9164b348919 667 return (int) ((360*getRollRadians()) / (2*PI));
MrBedfordVan 0:b9164b348919 668 }
MrBedfordVan 0:b9164b348919 669
MrBedfordVan 0:b9164b348919 670 /**
MrBedfordVan 0:b9164b348919 671 * Provides a rotation compensated roll of the device, based on the latest update retrieved from the accelerometer.
MrBedfordVan 0:b9164b348919 672 *
MrBedfordVan 0:b9164b348919 673 * @return The roll of the device, in radians.
MrBedfordVan 0:b9164b348919 674 *
MrBedfordVan 0:b9164b348919 675 * @code
MrBedfordVan 0:b9164b348919 676 * accelerometer.getRollRadians();
MrBedfordVan 0:b9164b348919 677 * @endcode
MrBedfordVan 0:b9164b348919 678 */
MrBedfordVan 0:b9164b348919 679 float MicroBitAccelerometer::getRollRadians()
MrBedfordVan 0:b9164b348919 680 {
MrBedfordVan 0:b9164b348919 681 if (!(status & MICROBIT_ACCEL_PITCH_ROLL_VALID))
MrBedfordVan 0:b9164b348919 682 recalculatePitchRoll();
MrBedfordVan 0:b9164b348919 683
MrBedfordVan 0:b9164b348919 684 return roll;
MrBedfordVan 0:b9164b348919 685 }
MrBedfordVan 0:b9164b348919 686
MrBedfordVan 0:b9164b348919 687 /**
MrBedfordVan 0:b9164b348919 688 * Recalculate roll and pitch values for the current sample.
MrBedfordVan 0:b9164b348919 689 *
MrBedfordVan 0:b9164b348919 690 * @note We only do this at most once per sample, as the necessary trigonemteric functions are rather
MrBedfordVan 0:b9164b348919 691 * heavyweight for a CPU without a floating point unit.
MrBedfordVan 0:b9164b348919 692 */
MrBedfordVan 0:b9164b348919 693 void MicroBitAccelerometer::recalculatePitchRoll()
MrBedfordVan 0:b9164b348919 694 {
MrBedfordVan 0:b9164b348919 695 double x = (double) getX(NORTH_EAST_DOWN);
MrBedfordVan 0:b9164b348919 696 double y = (double) getY(NORTH_EAST_DOWN);
MrBedfordVan 0:b9164b348919 697 double z = (double) getZ(NORTH_EAST_DOWN);
MrBedfordVan 0:b9164b348919 698
MrBedfordVan 0:b9164b348919 699 roll = atan2(y, z);
MrBedfordVan 0:b9164b348919 700 pitch = atan(-x / (y*sin(roll) + z*cos(roll)));
MrBedfordVan 0:b9164b348919 701
MrBedfordVan 0:b9164b348919 702 status |= MICROBIT_ACCEL_PITCH_ROLL_VALID;
MrBedfordVan 0:b9164b348919 703 }
MrBedfordVan 0:b9164b348919 704
MrBedfordVan 0:b9164b348919 705 /**
MrBedfordVan 0:b9164b348919 706 * Retrieves the last recorded gesture.
MrBedfordVan 0:b9164b348919 707 *
MrBedfordVan 0:b9164b348919 708 * @return The last gesture that was detected.
MrBedfordVan 0:b9164b348919 709 *
MrBedfordVan 0:b9164b348919 710 * Example:
MrBedfordVan 0:b9164b348919 711 * @code
MrBedfordVan 0:b9164b348919 712 * MicroBitDisplay display;
MrBedfordVan 0:b9164b348919 713 *
MrBedfordVan 0:b9164b348919 714 * if (accelerometer.getGesture() == SHAKE)
MrBedfordVan 0:b9164b348919 715 * display.scroll("SHAKE!");
MrBedfordVan 0:b9164b348919 716 * @endcode
MrBedfordVan 0:b9164b348919 717 */
MrBedfordVan 0:b9164b348919 718 uint16_t MicroBitAccelerometer::getGesture()
MrBedfordVan 0:b9164b348919 719 {
MrBedfordVan 0:b9164b348919 720 return lastGesture;
MrBedfordVan 0:b9164b348919 721 }
MrBedfordVan 0:b9164b348919 722
MrBedfordVan 0:b9164b348919 723 /**
MrBedfordVan 0:b9164b348919 724 * A periodic callback invoked by the fiber scheduler idle thread.
MrBedfordVan 0:b9164b348919 725 *
MrBedfordVan 0:b9164b348919 726 * Internally calls updateSample().
MrBedfordVan 0:b9164b348919 727 */
MrBedfordVan 0:b9164b348919 728 void MicroBitAccelerometer::idleTick()
MrBedfordVan 0:b9164b348919 729 {
MrBedfordVan 0:b9164b348919 730 updateSample();
MrBedfordVan 0:b9164b348919 731 }
MrBedfordVan 0:b9164b348919 732
MrBedfordVan 0:b9164b348919 733 /**
MrBedfordVan 0:b9164b348919 734 * Destructor for MicroBitAccelerometer, where we deregister from the array of fiber components.
MrBedfordVan 0:b9164b348919 735 */
MrBedfordVan 0:b9164b348919 736 MicroBitAccelerometer::~MicroBitAccelerometer()
MrBedfordVan 0:b9164b348919 737 {
MrBedfordVan 0:b9164b348919 738 fiber_remove_idle_component(this);
MrBedfordVan 0:b9164b348919 739 }
MrBedfordVan 0:b9164b348919 740
MrBedfordVan 0:b9164b348919 741 const MMA8653SampleRangeConfig MMA8653SampleRange[MMA8653_SAMPLE_RANGES] = {
MrBedfordVan 0:b9164b348919 742 {2, 0},
MrBedfordVan 0:b9164b348919 743 {4, 1},
MrBedfordVan 0:b9164b348919 744 {8, 2}
MrBedfordVan 0:b9164b348919 745 };
MrBedfordVan 0:b9164b348919 746
MrBedfordVan 0:b9164b348919 747 const MMA8653SampleRateConfig MMA8653SampleRate[MMA8653_SAMPLE_RATES] = {
MrBedfordVan 0:b9164b348919 748 {1250, 0x00},
MrBedfordVan 0:b9164b348919 749 {2500, 0x08},
MrBedfordVan 0:b9164b348919 750 {5000, 0x10},
MrBedfordVan 0:b9164b348919 751 {10000, 0x18},
MrBedfordVan 0:b9164b348919 752 {20000, 0x20},
MrBedfordVan 0:b9164b348919 753 {80000, 0x28},
MrBedfordVan 0:b9164b348919 754 {160000, 0x30},
MrBedfordVan 0:b9164b348919 755 {640000, 0x38}
MrBedfordVan 0:b9164b348919 756 };