Abdul Alf / Mbed 2 deprecated SDP_Version3_Abdul

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Dependencies:   BLE_API mbed nRF51822

Fork of SDP_Version3_Abdul by Michael Galis

MMA8452Q.cpp@7:79e6de3b27d4, 2017-02-26 (annotated)

Committer:
alfayeza
Date:
Sun Feb 26 06:37:07 2017 +0000
Revision:
7:79e6de3b27d4
Parent:
5:fd83a2ac378e 
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UserRevisionLine numberNew contents of line
galism 5:fd83a2ac378e 1 // Library for our MMA8452Q 3-axis accelerometer
galism 5:fd83a2ac378e 2 // Based on the MMA8452Q Arduino Library by Jim Lindblom (SparkFun Electronics)
galism 5:fd83a2ac378e 3
galism 5:fd83a2ac378e 4 #include "mbed.h"
galism 5:fd83a2ac378e 5 #include "MMA8452Q.h"
galism 5:fd83a2ac378e 6
galism 5:fd83a2ac378e 7 // Constructor
galism 5:fd83a2ac378e 8 MMA8452Q::MMA8452Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr)
galism 5:fd83a2ac378e 9 {
galism 5:fd83a2ac378e 10 // Initialize members
galism 5:fd83a2ac378e 11 scale = DEFAULT_FSR;
galism 5:fd83a2ac378e 12 }
galism 5:fd83a2ac378e 13
galism 5:fd83a2ac378e 14 // Destructor
galism 5:fd83a2ac378e 15 MMA8452Q::~MMA8452Q()
galism 5:fd83a2ac378e 16 {
galism 5:fd83a2ac378e 17
galism 5:fd83a2ac378e 18 }
galism 5:fd83a2ac378e 19
galism 5:fd83a2ac378e 20 // Initialization
galism 5:fd83a2ac378e 21 bool MMA8452Q::init()
galism 5:fd83a2ac378e 22 {
galism 5:fd83a2ac378e 23 // Check to make sure the chip's ID matches the factory ID
galism 5:fd83a2ac378e 24 uint8_t c = readRegister(REG_WHO_AM_I);
galism 5:fd83a2ac378e 25 if( c != FACTORY_ID ) {
galism 5:fd83a2ac378e 26 return false;
galism 5:fd83a2ac378e 27 }
galism 5:fd83a2ac378e 28
galism 5:fd83a2ac378e 29 // Set default scale and data rate
galism 5:fd83a2ac378e 30 standby();
galism 5:fd83a2ac378e 31 setScale(DEFAULT_FSR);
galism 5:fd83a2ac378e 32 setODR(DEFAULT_ODR);
galism 5:fd83a2ac378e 33 active();
galism 5:fd83a2ac378e 34
galism 5:fd83a2ac378e 35 return true;
galism 5:fd83a2ac378e 36 }
galism 5:fd83a2ac378e 37
galism 5:fd83a2ac378e 38 // Set the full-scale range for x, y, and z data
galism 5:fd83a2ac378e 39 void MMA8452Q::setScale(uint8_t fsr)
galism 5:fd83a2ac378e 40 {
galism 5:fd83a2ac378e 41 uint8_t config = readRegister(REG_XYZ_DATA_CFG);
galism 5:fd83a2ac378e 42 scale = fsr;
galism 5:fd83a2ac378e 43 config &= 0xFC; // Mask out FSR bits
galism 5:fd83a2ac378e 44 fsr = fsr >> 2; // Trick to translate scale to FSR bits
galism 5:fd83a2ac378e 45 fsr &= 0x03; // Mask out acceptable FSRs
galism 5:fd83a2ac378e 46 config |= fsr; // Write FSR bits to config byte
galism 5:fd83a2ac378e 47 writeRegister(REG_XYZ_DATA_CFG, config); // Write config back to register
galism 5:fd83a2ac378e 48 }
galism 5:fd83a2ac378e 49
galism 5:fd83a2ac378e 50 // Set the Output Data Rate
galism 5:fd83a2ac378e 51 void MMA8452Q::setODR(uint8_t odr)
galism 5:fd83a2ac378e 52 {
galism 5:fd83a2ac378e 53 uint8_t ctrl = readRegister(REG_CTRL_REG1);
galism 5:fd83a2ac378e 54 ctrl &= 0xCF; // Mask out data rate bits
galism 5:fd83a2ac378e 55 odr &= 0x07; // Mask out acceptable ODRs
galism 5:fd83a2ac378e 56 ctrl |= (odr << 3); // Write ODR bits to control byte
galism 5:fd83a2ac378e 57 writeRegister(REG_CTRL_REG1, ctrl); // Write control back to register
galism 5:fd83a2ac378e 58 }
galism 5:fd83a2ac378e 59
galism 5:fd83a2ac378e 60 // Set accelerometer into standby mode
galism 5:fd83a2ac378e 61 void MMA8452Q::standby()
galism 5:fd83a2ac378e 62 {
galism 5:fd83a2ac378e 63 uint8_t c = readRegister(REG_CTRL_REG1);
galism 5:fd83a2ac378e 64 c &= ~(0x01); // Clear bit 0 to go into standby
galism 5:fd83a2ac378e 65 writeRegister(REG_CTRL_REG1, c); // Write back to CONTROL register
galism 5:fd83a2ac378e 66 }
galism 5:fd83a2ac378e 67
galism 5:fd83a2ac378e 68 // Set accelerometer into active mode
galism 5:fd83a2ac378e 69 void MMA8452Q::active()
galism 5:fd83a2ac378e 70 {
galism 5:fd83a2ac378e 71 uint8_t c = readRegister(REG_CTRL_REG1);
galism 5:fd83a2ac378e 72 c |= 0x01; // Set bit 0 to go into active mode
galism 5:fd83a2ac378e 73 writeRegister(REG_CTRL_REG1, c); // Write back to CONTROL register
galism 5:fd83a2ac378e 74 }
galism 5:fd83a2ac378e 75
galism 5:fd83a2ac378e 76 // Read X registers
galism 5:fd83a2ac378e 77 float MMA8452Q::readX()
galism 5:fd83a2ac378e 78 {
galism 5:fd83a2ac378e 79 int16_t x = 0;
galism 5:fd83a2ac378e 80 float cx = 0;
galism 5:fd83a2ac378e 81
galism 5:fd83a2ac378e 82 // Read MSB and LSB from X registers
galism 5:fd83a2ac378e 83 x = readRegister(OUT_X_MSB);
galism 5:fd83a2ac378e 84 x = x << 8;
galism 5:fd83a2ac378e 85 x |= readRegister(OUT_X_LSB);
galism 5:fd83a2ac378e 86 x = x >> 4;
galism 5:fd83a2ac378e 87
galism 5:fd83a2ac378e 88 // Calculate human readable X
galism 5:fd83a2ac378e 89 cx = (float)x / (float)2048 * (float)(scale);
galism 5:fd83a2ac378e 90
galism 5:fd83a2ac378e 91 return cx;
galism 5:fd83a2ac378e 92 }
galism 5:fd83a2ac378e 93
galism 5:fd83a2ac378e 94 // Read Y registers
galism 5:fd83a2ac378e 95 float MMA8452Q::readY()
galism 5:fd83a2ac378e 96 {
galism 5:fd83a2ac378e 97 int16_t y = 0;
galism 5:fd83a2ac378e 98 float cy = 0;
galism 5:fd83a2ac378e 99
galism 5:fd83a2ac378e 100 // Read MSB and LSB from Y registers
galism 5:fd83a2ac378e 101 y = readRegister(OUT_Y_MSB);
galism 5:fd83a2ac378e 102 y = y << 8;
galism 5:fd83a2ac378e 103 y |= readRegister(OUT_Y_LSB);
galism 5:fd83a2ac378e 104 y = y >> 4;
galism 5:fd83a2ac378e 105
galism 5:fd83a2ac378e 106 // Calculate human readable Y
galism 5:fd83a2ac378e 107 cy = (float)y / (float)2048 * (float)(scale);
galism 5:fd83a2ac378e 108
galism 5:fd83a2ac378e 109 return cy;
galism 5:fd83a2ac378e 110 }
galism 5:fd83a2ac378e 111
galism 5:fd83a2ac378e 112 // Read Z registers
galism 5:fd83a2ac378e 113 float MMA8452Q::readZ()
galism 5:fd83a2ac378e 114 {
galism 5:fd83a2ac378e 115 int16_t z = 0;
galism 5:fd83a2ac378e 116 float cz = 0;
galism 5:fd83a2ac378e 117
galism 5:fd83a2ac378e 118 // Read MSB and LSB from Z registers
galism 5:fd83a2ac378e 119 z = readRegister(OUT_Z_MSB);
galism 5:fd83a2ac378e 120 z = z << 8;
galism 5:fd83a2ac378e 121 z |= readRegister(OUT_Z_LSB);
galism 5:fd83a2ac378e 122 z = z >> 4;
galism 5:fd83a2ac378e 123
galism 5:fd83a2ac378e 124 // Calculate human readable Z
galism 5:fd83a2ac378e 125 cz = (float)z / (float)2048 * (float)(scale);
galism 5:fd83a2ac378e 126
galism 5:fd83a2ac378e 127 return cz;
galism 5:fd83a2ac378e 128 }
galism 5:fd83a2ac378e 129
galism 5:fd83a2ac378e 130 // Raw read register over I2C
galism 5:fd83a2ac378e 131 uint8_t MMA8452Q::readRegister(uint8_t reg)
galism 5:fd83a2ac378e 132 {
galism 5:fd83a2ac378e 133 uint8_t dev_addr;
galism 5:fd83a2ac378e 134 uint8_t data;
galism 5:fd83a2ac378e 135
galism 5:fd83a2ac378e 136 // I2C address are bits [6..1] in the transmitted byte, so we shift by 1
galism 5:fd83a2ac378e 137 dev_addr = m_addr << 1;
galism 5:fd83a2ac378e 138
galism 5:fd83a2ac378e 139 // Write device address with a trailing 'write' bit
galism 5:fd83a2ac378e 140 m_i2c.start();
galism 5:fd83a2ac378e 141 m_i2c.write(dev_addr & 0xFE);
galism 5:fd83a2ac378e 142
galism 5:fd83a2ac378e 143 // Write register address
galism 5:fd83a2ac378e 144 m_i2c.write(reg);
galism 5:fd83a2ac378e 145
galism 5:fd83a2ac378e 146 // Write a start bit and device address with a trailing 'read' bit
galism 5:fd83a2ac378e 147 m_i2c.start();
galism 5:fd83a2ac378e 148 m_i2c.write(dev_addr | 0x01);
galism 5:fd83a2ac378e 149
galism 5:fd83a2ac378e 150 // Read single byte from I2C device
galism 5:fd83a2ac378e 151 data = m_i2c.read(0);
galism 5:fd83a2ac378e 152 m_i2c.stop();
galism 5:fd83a2ac378e 153
galism 5:fd83a2ac378e 154 return data;
galism 5:fd83a2ac378e 155 }
galism 5:fd83a2ac378e 156
galism 5:fd83a2ac378e 157 char MMA8452Q::getMaskedRegister(int addr, char mask) {
galism 5:fd83a2ac378e 158 char rval = 0;
galism 5:fd83a2ac378e 159 if(readRegister(addr)) {
galism 5:fd83a2ac378e 160 return 0;
galism 5:fd83a2ac378e 161 }
galism 5:fd83a2ac378e 162 return (rval&mask);
galism 5:fd83a2ac378e 163 }
galism 5:fd83a2ac378e 164
galism 5:fd83a2ac378e 165 int MMA8452Q::isXYZReady() {
galism 5:fd83a2ac378e 166 return getMaskedRegister(REG_STATUS ,MMA8452_STATUS_ZYXDR_MASK)>0;
galism 5:fd83a2ac378e 167 }
galism 5:fd83a2ac378e 168
galism 5:fd83a2ac378e 169 bool MMA8452Q::available(){
galism 5:fd83a2ac378e 170 return (readRegister(REG_STATUS) & 0x08) >> 3;
galism 5:fd83a2ac378e 171 }
galism 5:fd83a2ac378e 172
galism 5:fd83a2ac378e 173 // Raw write data to a register over I2C
galism 5:fd83a2ac378e 174 void MMA8452Q::writeRegister(uint8_t reg, uint8_t data)
galism 5:fd83a2ac378e 175 {
galism 5:fd83a2ac378e 176 uint8_t dev_addr;
galism 5:fd83a2ac378e 177
galism 5:fd83a2ac378e 178 // I2C address are bits [6..1] in the transmitted byte, so we shift by 1
galism 5:fd83a2ac378e 179 dev_addr = m_addr << 1;
galism 5:fd83a2ac378e 180
galism 5:fd83a2ac378e 181 // Write device address with a trailing 'write' bit
galism 5:fd83a2ac378e 182 m_i2c.start();
galism 5:fd83a2ac378e 183 m_i2c.write(dev_addr & 0xFE);
galism 5:fd83a2ac378e 184
galism 5:fd83a2ac378e 185 // Write register address
galism 5:fd83a2ac378e 186 m_i2c.write(reg);
galism 5:fd83a2ac378e 187
galism 5:fd83a2ac378e 188 // Write the data to the register
galism 5:fd83a2ac378e 189 m_i2c.write(data);
galism 5:fd83a2ac378e 190 m_i2c.stop();
galism 5:fd83a2ac378e 191 }