Kaitlyn Barros / MMA8452Q

Updated OCE 360 Assignment 4

Dependents:   Barros_Assignment4

MMA8452Q.cpp@2:1d10bcf263d2, 2017-12-07 (annotated)

Committer:
Kaitlyn_Barros
Date:
Thu Dec 07 23:20:41 2017 +0000
Revision:
2:1d10bcf263d2
Parent:
0:098406435cd2 
Assignment 6. Attempt to employ free fall register.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Kaitlyn_Barros 0:098406435cd2 1 // Library for our MMA8452Q 3-axis accelerometer
Kaitlyn_Barros 0:098406435cd2 2 // Based on the MMA8452Q Arduino Library by Jim Lindblom (SparkFun Electronics)
Kaitlyn_Barros 0:098406435cd2 3
Kaitlyn_Barros 0:098406435cd2 4 #include "mbed.h"
Kaitlyn_Barros 0:098406435cd2 5 #include "MMA8452Q.h"
Kaitlyn_Barros 0:098406435cd2 6
Kaitlyn_Barros 0:098406435cd2 7 // Constructor
Kaitlyn_Barros 0:098406435cd2 8 MMA8452Q::MMA8452Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr)
Kaitlyn_Barros 0:098406435cd2 9 {
Kaitlyn_Barros 0:098406435cd2 10 // Initialize members
Kaitlyn_Barros 0:098406435cd2 11 scale = DEFAULT_FSR;
Kaitlyn_Barros 0:098406435cd2 12 }
Kaitlyn_Barros 0:098406435cd2 13
Kaitlyn_Barros 0:098406435cd2 14 // Destructor
Kaitlyn_Barros 0:098406435cd2 15 MMA8452Q::~MMA8452Q()
Kaitlyn_Barros 0:098406435cd2 16 {
Kaitlyn_Barros 0:098406435cd2 17
Kaitlyn_Barros 0:098406435cd2 18 }
Kaitlyn_Barros 0:098406435cd2 19
Kaitlyn_Barros 0:098406435cd2 20 // Initialization
Kaitlyn_Barros 0:098406435cd2 21 bool MMA8452Q::init()
Kaitlyn_Barros 0:098406435cd2 22 {
Kaitlyn_Barros 0:098406435cd2 23 // Check to make sure the chip's ID matches the factory ID
Kaitlyn_Barros 0:098406435cd2 24 uint8_t c = readRegister(REG_WHO_AM_I);
Kaitlyn_Barros 0:098406435cd2 25 if( c != FACTORY_ID ) {
Kaitlyn_Barros 0:098406435cd2 26 return false;
Kaitlyn_Barros 0:098406435cd2 27 }
Kaitlyn_Barros 0:098406435cd2 28
Kaitlyn_Barros 0:098406435cd2 29 // Set default scale and data rate
Kaitlyn_Barros 0:098406435cd2 30 standby();
Kaitlyn_Barros 0:098406435cd2 31 setScale(DEFAULT_FSR);
Kaitlyn_Barros 0:098406435cd2 32 setODR(DEFAULT_ODR);
Kaitlyn_Barros 0:098406435cd2 33 active();
Kaitlyn_Barros 0:098406435cd2 34
Kaitlyn_Barros 0:098406435cd2 35 return true;
Kaitlyn_Barros 0:098406435cd2 36 }
Kaitlyn_Barros 0:098406435cd2 37
Kaitlyn_Barros 0:098406435cd2 38 // Set the full-scale range for x, y, and z data
Kaitlyn_Barros 0:098406435cd2 39 void MMA8452Q::setScale(uint8_t fsr)
Kaitlyn_Barros 0:098406435cd2 40 {
Kaitlyn_Barros 0:098406435cd2 41 uint8_t config = readRegister(REG_XYZ_DATA_CFG);
Kaitlyn_Barros 0:098406435cd2 42 scale = fsr;
Kaitlyn_Barros 0:098406435cd2 43 config &= 0xFC; // Mask out FSR bits
Kaitlyn_Barros 0:098406435cd2 44 fsr = fsr >> 2; // Trick to translate scale to FSR bits
Kaitlyn_Barros 0:098406435cd2 45 fsr &= 0x03; // Mask out acceptable FSRs
Kaitlyn_Barros 0:098406435cd2 46 config |= fsr; // Write FSR bits to config byte
Kaitlyn_Barros 0:098406435cd2 47 writeRegister(REG_XYZ_DATA_CFG, config); // Write config back to register
Kaitlyn_Barros 0:098406435cd2 48 }
Kaitlyn_Barros 0:098406435cd2 49
Kaitlyn_Barros 0:098406435cd2 50 // Set the Output Data Rate
Kaitlyn_Barros 0:098406435cd2 51 void MMA8452Q::setODR(uint8_t odr)
Kaitlyn_Barros 0:098406435cd2 52 {
Kaitlyn_Barros 0:098406435cd2 53 uint8_t ctrl = readRegister(REG_CTRL_REG1);
Kaitlyn_Barros 0:098406435cd2 54 ctrl &= 0xCF; // Mask out data rate bits
Kaitlyn_Barros 0:098406435cd2 55 odr &= 0x07; // Mask out acceptable ODRs
Kaitlyn_Barros 0:098406435cd2 56 ctrl |= (odr << 3); // Write ODR bits to control byte
Kaitlyn_Barros 0:098406435cd2 57 writeRegister(REG_CTRL_REG1, ctrl); // Write control back to register
Kaitlyn_Barros 0:098406435cd2 58 }
Kaitlyn_Barros 0:098406435cd2 59
Kaitlyn_Barros 0:098406435cd2 60 // Set accelerometer into standby mode
Kaitlyn_Barros 0:098406435cd2 61 void MMA8452Q::standby()
Kaitlyn_Barros 0:098406435cd2 62 {
Kaitlyn_Barros 0:098406435cd2 63 uint8_t c = readRegister(REG_CTRL_REG1);
Kaitlyn_Barros 0:098406435cd2 64 c &= ~(0x01); // Clear bit 0 to go into standby
Kaitlyn_Barros 0:098406435cd2 65 writeRegister(REG_CTRL_REG1, c); // Write back to CONTROL register
Kaitlyn_Barros 0:098406435cd2 66 }
Kaitlyn_Barros 0:098406435cd2 67
Kaitlyn_Barros 0:098406435cd2 68 // Set accelerometer into active mode
Kaitlyn_Barros 0:098406435cd2 69 void MMA8452Q::active()
Kaitlyn_Barros 0:098406435cd2 70 {
Kaitlyn_Barros 0:098406435cd2 71 uint8_t c = readRegister(REG_CTRL_REG1);
Kaitlyn_Barros 0:098406435cd2 72 c |= 0x01; // Set bit 0 to go into active mode
Kaitlyn_Barros 0:098406435cd2 73 writeRegister(REG_CTRL_REG1, c); // Write back to CONTROL register
Kaitlyn_Barros 0:098406435cd2 74 }
Kaitlyn_Barros 0:098406435cd2 75
Kaitlyn_Barros 2:1d10bcf263d2 76 // Set accelerometer into standby mode
Kaitlyn_Barros 2:1d10bcf263d2 77 void MMA8452Q::standby1()
Kaitlyn_Barros 2:1d10bcf263d2 78 {
Kaitlyn_Barros 2:1d10bcf263d2 79 uint8_t k = readRegister(REG_FF_MT_CFG);
Kaitlyn_Barros 2:1d10bcf263d2 80 k &= ~(0x07);
Kaitlyn_Barros 2:1d10bcf263d2 81 writeRegister(REG_FF_MT_CFG, k);
Kaitlyn_Barros 2:1d10bcf263d2 82 }
Kaitlyn_Barros 2:1d10bcf263d2 83 void MMA8452Q::active1()
Kaitlyn_Barros 2:1d10bcf263d2 84 {
Kaitlyn_Barros 2:1d10bcf263d2 85 uint8_t k = readRegister(REG_FF_MT_CFG);
Kaitlyn_Barros 2:1d10bcf263d2 86 k |= ~0x07;
Kaitlyn_Barros 2:1d10bcf263d2 87 writeRegister(REG_FF_MT_CFG, k);
Kaitlyn_Barros 2:1d10bcf263d2 88 }
Kaitlyn_Barros 2:1d10bcf263d2 89
Kaitlyn_Barros 0:098406435cd2 90 // Read X registers
Kaitlyn_Barros 0:098406435cd2 91 float MMA8452Q::readX()
Kaitlyn_Barros 0:098406435cd2 92 {
Kaitlyn_Barros 0:098406435cd2 93 int16_t x = 0;
Kaitlyn_Barros 0:098406435cd2 94 float cx = 0;
Kaitlyn_Barros 0:098406435cd2 95
Kaitlyn_Barros 0:098406435cd2 96 // Read MSB and LSB from X registers
Kaitlyn_Barros 0:098406435cd2 97 x = readRegister(OUT_X_MSB);
Kaitlyn_Barros 0:098406435cd2 98 x = x << 8;
Kaitlyn_Barros 0:098406435cd2 99 x |= readRegister(OUT_X_LSB);
Kaitlyn_Barros 0:098406435cd2 100 x = x >> 4;
Kaitlyn_Barros 0:098406435cd2 101
Kaitlyn_Barros 0:098406435cd2 102 // Calculate human readable X
Kaitlyn_Barros 0:098406435cd2 103 cx = (float)x / (float)2048 * (float)(scale);
Kaitlyn_Barros 0:098406435cd2 104
Kaitlyn_Barros 0:098406435cd2 105 return cx;
Kaitlyn_Barros 0:098406435cd2 106 }
Kaitlyn_Barros 0:098406435cd2 107
Kaitlyn_Barros 0:098406435cd2 108 // Read Y registers
Kaitlyn_Barros 0:098406435cd2 109 float MMA8452Q::readY()
Kaitlyn_Barros 0:098406435cd2 110 {
Kaitlyn_Barros 0:098406435cd2 111 int16_t y = 0;
Kaitlyn_Barros 0:098406435cd2 112 float cy = 0;
Kaitlyn_Barros 0:098406435cd2 113
Kaitlyn_Barros 0:098406435cd2 114 // Read MSB and LSB from Y registers
Kaitlyn_Barros 0:098406435cd2 115 y = readRegister(OUT_Y_MSB);
Kaitlyn_Barros 0:098406435cd2 116 y = y << 8;
Kaitlyn_Barros 0:098406435cd2 117 y |= readRegister(OUT_Y_LSB);
Kaitlyn_Barros 0:098406435cd2 118 y = y >> 4;
Kaitlyn_Barros 0:098406435cd2 119
Kaitlyn_Barros 0:098406435cd2 120 // Calculate human readable Y
Kaitlyn_Barros 0:098406435cd2 121 cy = (float)y / (float)2048 * (float)(scale);
Kaitlyn_Barros 0:098406435cd2 122
Kaitlyn_Barros 0:098406435cd2 123 return cy;
Kaitlyn_Barros 0:098406435cd2 124 }
Kaitlyn_Barros 0:098406435cd2 125
Kaitlyn_Barros 0:098406435cd2 126 // Read Z registers
Kaitlyn_Barros 0:098406435cd2 127 float MMA8452Q::readZ()
Kaitlyn_Barros 0:098406435cd2 128 {
Kaitlyn_Barros 0:098406435cd2 129 int16_t z = 0;
Kaitlyn_Barros 0:098406435cd2 130 float cz = 0;
Kaitlyn_Barros 0:098406435cd2 131
Kaitlyn_Barros 0:098406435cd2 132 // Read MSB and LSB from Z registers
Kaitlyn_Barros 0:098406435cd2 133 z = readRegister(OUT_Z_MSB);
Kaitlyn_Barros 0:098406435cd2 134 z = z << 8;
Kaitlyn_Barros 0:098406435cd2 135 z |= readRegister(OUT_Z_LSB);
Kaitlyn_Barros 0:098406435cd2 136 z = z >> 4;
Kaitlyn_Barros 0:098406435cd2 137
Kaitlyn_Barros 0:098406435cd2 138 // Calculate human readable Z
Kaitlyn_Barros 0:098406435cd2 139 cz = (float)z / (float)2048 * (float)(scale);
Kaitlyn_Barros 0:098406435cd2 140
Kaitlyn_Barros 0:098406435cd2 141 return cz;
Kaitlyn_Barros 0:098406435cd2 142 }
Kaitlyn_Barros 0:098406435cd2 143
Kaitlyn_Barros 0:098406435cd2 144 // Raw read register over I2C
Kaitlyn_Barros 0:098406435cd2 145 uint8_t MMA8452Q::readRegister(uint8_t reg)
Kaitlyn_Barros 0:098406435cd2 146 {
Kaitlyn_Barros 0:098406435cd2 147 uint8_t dev_addr;
Kaitlyn_Barros 0:098406435cd2 148 uint8_t data;
Kaitlyn_Barros 0:098406435cd2 149
Kaitlyn_Barros 0:098406435cd2 150 // I2C address are bits [6..1] in the transmitted byte, so we shift by 1
Kaitlyn_Barros 0:098406435cd2 151 dev_addr = m_addr << 1;
Kaitlyn_Barros 0:098406435cd2 152
Kaitlyn_Barros 0:098406435cd2 153 // Write device address with a trailing 'write' bit
Kaitlyn_Barros 0:098406435cd2 154 m_i2c.start();
Kaitlyn_Barros 0:098406435cd2 155 m_i2c.write(dev_addr & 0xFE);
Kaitlyn_Barros 0:098406435cd2 156
Kaitlyn_Barros 0:098406435cd2 157 // Write register address
Kaitlyn_Barros 0:098406435cd2 158 m_i2c.write(reg);
Kaitlyn_Barros 0:098406435cd2 159
Kaitlyn_Barros 0:098406435cd2 160 // Write a start bit and device address with a trailing 'read' bit
Kaitlyn_Barros 0:098406435cd2 161 m_i2c.start();
Kaitlyn_Barros 0:098406435cd2 162 m_i2c.write(dev_addr | 0x01);
Kaitlyn_Barros 0:098406435cd2 163
Kaitlyn_Barros 0:098406435cd2 164 // Read single byte from I2C device
Kaitlyn_Barros 0:098406435cd2 165 data = m_i2c.read(0);
Kaitlyn_Barros 0:098406435cd2 166 m_i2c.stop();
Kaitlyn_Barros 0:098406435cd2 167
Kaitlyn_Barros 0:098406435cd2 168 return data;
Kaitlyn_Barros 0:098406435cd2 169 }
Kaitlyn_Barros 0:098406435cd2 170
Kaitlyn_Barros 0:098406435cd2 171 // Raw write data to a register over I2C
Kaitlyn_Barros 0:098406435cd2 172 void MMA8452Q::writeRegister(uint8_t reg, uint8_t data)
Kaitlyn_Barros 0:098406435cd2 173 {
Kaitlyn_Barros 0:098406435cd2 174 uint8_t dev_addr;
Kaitlyn_Barros 0:098406435cd2 175
Kaitlyn_Barros 0:098406435cd2 176 // I2C address are bits [6..1] in the transmitted byte, so we shift by 1
Kaitlyn_Barros 0:098406435cd2 177 dev_addr = m_addr << 1;
Kaitlyn_Barros 0:098406435cd2 178
Kaitlyn_Barros 0:098406435cd2 179 // Write device address with a trailing 'write' bit
Kaitlyn_Barros 0:098406435cd2 180 m_i2c.start();
Kaitlyn_Barros 0:098406435cd2 181 m_i2c.write(dev_addr & 0xFE);
Kaitlyn_Barros 0:098406435cd2 182
Kaitlyn_Barros 0:098406435cd2 183 // Write register address
Kaitlyn_Barros 0:098406435cd2 184 m_i2c.write(reg);
Kaitlyn_Barros 0:098406435cd2 185
Kaitlyn_Barros 0:098406435cd2 186 // Write the data to the register
Kaitlyn_Barros 0:098406435cd2 187 m_i2c.write(data);
Kaitlyn_Barros 0:098406435cd2 188 m_i2c.stop();
Kaitlyn_Barros 2:1d10bcf263d2 189 }
Kaitlyn_Barros 2:1d10bcf263d2 190
Kaitlyn_Barros 2:1d10bcf263d2 191 //IIC_RegWrite(0x15, 0xB8); //Enable Latch, Freefall, X-axis, Y-axis and Z-axis