Nicholas Herriot / MMA8452

This is a simple device driver for the 3 axis accelerometer MMA8452 that works with mbed.

Dependents:   MMA8452_test S05APP3_routeur

MMA8452.cpp@0:bcf2aa85d7f9, 2013-10-04 (annotated)

Committer:
nherriot
Date:
Fri Oct 04 14:48:02 2013 +0000
Revision:
0:bcf2aa85d7f9
Child:
1:ef026bf28798
Initial commit fro mma8452

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nherriot 0:bcf2aa85d7f9 1 // Author: Nicholas Herriot
nherriot 0:bcf2aa85d7f9 2 /* Copyright (c) 2013 Vodafone, MIT License
nherriot 0:bcf2aa85d7f9 3 *
nherriot 0:bcf2aa85d7f9 4 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
nherriot 0:bcf2aa85d7f9 5 * and associated documentation files (the "Software"), to deal in the Software without restriction,
nherriot 0:bcf2aa85d7f9 6 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
nherriot 0:bcf2aa85d7f9 7 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
nherriot 0:bcf2aa85d7f9 8 * furnished to do so, subject to the following conditions:
nherriot 0:bcf2aa85d7f9 9 *
nherriot 0:bcf2aa85d7f9 10 * The above copyright notice and this permission notice shall be included in all copies or
nherriot 0:bcf2aa85d7f9 11 * substantial portions of the Software.
nherriot 0:bcf2aa85d7f9 12 *
nherriot 0:bcf2aa85d7f9 13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
nherriot 0:bcf2aa85d7f9 14 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
nherriot 0:bcf2aa85d7f9 15 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
nherriot 0:bcf2aa85d7f9 16 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
nherriot 0:bcf2aa85d7f9 17 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nherriot 0:bcf2aa85d7f9 18 */
nherriot 0:bcf2aa85d7f9 19
nherriot 0:bcf2aa85d7f9 20 # include "MMA8452.h"
nherriot 0:bcf2aa85d7f9 21
nherriot 0:bcf2aa85d7f9 22
nherriot 0:bcf2aa85d7f9 23
nherriot 0:bcf2aa85d7f9 24 float TILT_XY[64] = {0, 2.69, 5.38, 8.08, 10.81, 13.55, 16.33, 19.16, 22.02, 24.95, 27.95, 31.04, 34.23, 37.54, 41.01, 44.68, 48.59, 52.83, 57.54, 62.95, 69.64, 79.86, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -79.86, -69.64, -62.95, -57.54, -52.83, -48.59, -44.68, -41.01, -37.54, -34.23, -31.04, -27.95, -24.95, -22.02, -19.16, -16.33, -13.55, -10.81, -8.08, -5.38, -2.69};
nherriot 0:bcf2aa85d7f9 25 float TILT_Z[64] = {90.00, 87.31, 84.62, 81.92, 79.19, 76.45, 73.67, 70.84, 67.98, 65.05, 62.05, 58.96, 55.77, 52.46, 48.99, 45.32, 41.41, 37.17, 32.46, 27.05, 20.36, 10.14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -10.14, -20.36, -27.05, -32.46, -37.17, -41.41, -45.32, -48.99, -52.46, -55.77, -58.96, -62.05, -65.05, -67.98, -70.84, -73.67, -76.45, -79.19, -81.92, -84.62};
nherriot 0:bcf2aa85d7f9 26
nherriot 0:bcf2aa85d7f9 27
nherriot 0:bcf2aa85d7f9 28
nherriot 0:bcf2aa85d7f9 29 // Connect module at I2C address using I2C port pins sda and scl
nherriot 0:bcf2aa85d7f9 30 Accelerometer_MMA8452::Accelerometer_MMA8452(PinName sda, PinName scl,int frequency) : m_i2c(sda, scl): m_frequency(frequency):
nherriot 0:bcf2aa85d7f9 31 {
nherriot 0:bcf2aa85d7f9 32 //m_i2c.frequency(m_frequency);
nherriot 0:bcf2aa85d7f9 33 }
nherriot 0:bcf2aa85d7f9 34
nherriot 0:bcf2aa85d7f9 35
nherriot 0:bcf2aa85d7f9 36 // Destroys instance
nherriot 0:bcf2aa85d7f9 37 Accelerometer_MMA8452::~Accelerometer_MMA8452()
nherriot 0:bcf2aa85d7f9 38 {
nherriot 0:bcf2aa85d7f9 39
nherriot 0:bcf2aa85d7f9 40 }
nherriot 0:bcf2aa85d7f9 41
nherriot 0:bcf2aa85d7f9 42 // Setting the control register bit 1 to true to activate the MMA8452
nherriot 0:bcf2aa85d7f9 43 int Accelerometer_MMA8452::activate()
nherriot 0:bcf2aa85d7f9 44 {
nherriot 0:bcf2aa85d7f9 45 char mcu_address = (MMA8452_ADDRESS <1);
nherriot 0:bcf2aa85d7f9 46 char init[2];
nherriot 0:bcf2aa85d7f9 47 init[0] = CTRL_REG_1; // control register 1
nherriot 0:bcf2aa85d7f9 48 init[1] = 0x01; // set to active
nherriot 0:bcf2aa85d7f9 49 if(m_i2c.write(mcu_address,init,2) == 0)
nherriot 0:bcf2aa85d7f9 50 {
nherriot 0:bcf2aa85d7f9 51 // pc.printf("The initialisation worked");
nherriot 0:bcf2aa85d7f9 52 return 0;
nherriot 0:bcf2aa85d7f9 53 }
nherriot 0:bcf2aa85d7f9 54 else
nherriot 0:bcf2aa85d7f9 55 {
nherriot 0:bcf2aa85d7f9 56 // pc.printf("The initialisation failed");
nherriot 0:bcf2aa85d7f9 57 return 1;
nherriot 0:bcf2aa85d7f9 58 }
nherriot 0:bcf2aa85d7f9 59
nherriot 0:bcf2aa85d7f9 60 }
nherriot 0:bcf2aa85d7f9 61
nherriot 0:bcf2aa85d7f9 62
nherriot 0:bcf2aa85d7f9 63 // Device initialization
nherriot 0:bcf2aa85d7f9 64 void Accelerometer_MMA8452::init()
nherriot 0:bcf2aa85d7f9 65 {
nherriot 0:bcf2aa85d7f9 66
nherriot 0:bcf2aa85d7f9 67 write_reg(INTSU_STATUS, 0x10); // automatic interrupt after every measurement
nherriot 0:bcf2aa85d7f9 68 write_reg(SR_STATUS, 0x00); // 120 Samples/Second
nherriot 0:bcf2aa85d7f9 69 write_reg(MODE_STATUS, 0x01); // Active Mode
nherriot 0:bcf2aa85d7f9 70
nherriot 0:bcf2aa85d7f9 71 }
nherriot 0:bcf2aa85d7f9 72
nherriot 0:bcf2aa85d7f9 73
nherriot 0:bcf2aa85d7f9 74 // Reads the tilt angle
nherriot 0:bcf2aa85d7f9 75 void Accelerometer_MMA8452::read_Tilt(float *x, float *y, float *z)
nherriot 0:bcf2aa85d7f9 76 {
nherriot 0:bcf2aa85d7f9 77
nherriot 0:bcf2aa85d7f9 78 const char Addr_X = OUT_X_MSB;
nherriot 0:bcf2aa85d7f9 79 char buf[3] = {0,0,0};
nherriot 0:bcf2aa85d7f9 80
nherriot 0:bcf2aa85d7f9 81 m_i2c.write(MMA8452_ADDRESS, &Addr_X, 1); // Pointer to the OUT_X_MSB register
nherriot 0:bcf2aa85d7f9 82 m_i2c.read(MMA8452_ADDRESS, buf, 3); // Read register content into buffer with 6bit
nherriot 0:bcf2aa85d7f9 83
nherriot 0:bcf2aa85d7f9 84 // returns the x, y, z coordinates transformed into full degrees
nherriot 0:bcf2aa85d7f9 85 *x = TILT_XY[(int)buf[0]];
nherriot 0:bcf2aa85d7f9 86 *y = TILT_XY[(int)buf[1]];
nherriot 0:bcf2aa85d7f9 87 *z = TILT_Z[(int)buf[2]];
nherriot 0:bcf2aa85d7f9 88
nherriot 0:bcf2aa85d7f9 89 }
nherriot 0:bcf2aa85d7f9 90
nherriot 0:bcf2aa85d7f9 91
nherriot 0:bcf2aa85d7f9 92 // Reads x data
nherriot 0:bcf2aa85d7f9 93 int Accelerometer_MMA8452::read_x()
nherriot 0:bcf2aa85d7f9 94 {
nherriot 0:bcf2aa85d7f9 95 char mcu_address = (MMA8452_ADDRESS <1);
nherriot 0:bcf2aa85d7f9 96
nherriot 0:bcf2aa85d7f9 97 m_i2c.start(); // Start
nherriot 0:bcf2aa85d7f9 98 m_i2c.write(mcu_address); // A write to device 0x98
nherriot 0:bcf2aa85d7f9 99 m_i2c.write(OUT_X_MSB); // Register to read
nherriot 0:bcf2aa85d7f9 100 m_i2c.start();
nherriot 0:bcf2aa85d7f9 101 m_i2c.write(mcu_address); // Read from device 0x99
nherriot 0:bcf2aa85d7f9 102 char x = m_i2c.read(0); // Read the data
nherriot 0:bcf2aa85d7f9 103 m_i2c.stop();
nherriot 0:bcf2aa85d7f9 104
nherriot 0:bcf2aa85d7f9 105 return (int)x;
nherriot 0:bcf2aa85d7f9 106
nherriot 0:bcf2aa85d7f9 107 }
nherriot 0:bcf2aa85d7f9 108
nherriot 0:bcf2aa85d7f9 109
nherriot 0:bcf2aa85d7f9 110 // Reads y data
nherriot 0:bcf2aa85d7f9 111 int Accelerometer_MMA8452::read_y()
nherriot 0:bcf2aa85d7f9 112 {
nherriot 0:bcf2aa85d7f9 113 char mcu_address = (MMA8452_ADDRESS <1);
nherriot 0:bcf2aa85d7f9 114
nherriot 0:bcf2aa85d7f9 115 m_i2c.start(); // Start
nherriot 0:bcf2aa85d7f9 116 m_i2c.write(mcu_address); // A write to device 0x98
nherriot 0:bcf2aa85d7f9 117 m_i2c.write(OUT_Y_MSB); // Register to read
nherriot 0:bcf2aa85d7f9 118 m_i2c.start();
nherriot 0:bcf2aa85d7f9 119 m_i2c.write(mcu_address); // Read from device 0x99
nherriot 0:bcf2aa85d7f9 120 char y = m_i2c.read(0); // Read the data
nherriot 0:bcf2aa85d7f9 121 m_i2c.stop();
nherriot 0:bcf2aa85d7f9 122
nherriot 0:bcf2aa85d7f9 123 return (int)y;
nherriot 0:bcf2aa85d7f9 124
nherriot 0:bcf2aa85d7f9 125 }
nherriot 0:bcf2aa85d7f9 126
nherriot 0:bcf2aa85d7f9 127
nherriot 0:bcf2aa85d7f9 128 // Reads z data
nherriot 0:bcf2aa85d7f9 129 int Accelerometer_MMA8452::read_z()
nherriot 0:bcf2aa85d7f9 130 {
nherriot 0:bcf2aa85d7f9 131 char mcu_address = (MMA8452_ADDRESS <1);
nherriot 0:bcf2aa85d7f9 132
nherriot 0:bcf2aa85d7f9 133 m_i2c.start(); // Start
nherriot 0:bcf2aa85d7f9 134 m_i2c.write(mcu_address); // A write to device 0x98
nherriot 0:bcf2aa85d7f9 135 m_i2c.write(OUT_Z_MSB); // Register to read
nherriot 0:bcf2aa85d7f9 136 m_i2c.start();
nherriot 0:bcf2aa85d7f9 137 m_i2c.write(mcu_address); // Read from device 0x99
nherriot 0:bcf2aa85d7f9 138 char z = m_i2c.read(0); // Read the data
nherriot 0:bcf2aa85d7f9 139 m_i2c.stop();
nherriot 0:bcf2aa85d7f9 140
nherriot 0:bcf2aa85d7f9 141 return (int)z;
nherriot 0:bcf2aa85d7f9 142
nherriot 0:bcf2aa85d7f9 143 }
nherriot 0:bcf2aa85d7f9 144
nherriot 0:bcf2aa85d7f9 145
nherriot 0:bcf2aa85d7f9 146 // Reads xyz
nherriot 0:bcf2aa85d7f9 147
nherriot 0:bcf2aa85d7f9 148
nherriot 0:bcf2aa85d7f9 149
nherriot 0:bcf2aa85d7f9 150
nherriot 0:bcf2aa85d7f9 151 // Write register (The device must be placed in Standby Mode to change the value of the registers)
nherriot 0:bcf2aa85d7f9 152 void Accelerometer_MMA8452::write_reg(char addr, char data)
nherriot 0:bcf2aa85d7f9 153 {
nherriot 0:bcf2aa85d7f9 154
nherriot 0:bcf2aa85d7f9 155 char cmd[2] = {0, 0};
nherriot 0:bcf2aa85d7f9 156
nherriot 0:bcf2aa85d7f9 157 cmd[0] = MODE_STATUS;
nherriot 0:bcf2aa85d7f9 158 cmd[1] = 0x00; // Standby Mode on
nherriot 0:bcf2aa85d7f9 159 m_i2c.write(MMA8452_ADDRESS, cmd, 2);
nherriot 0:bcf2aa85d7f9 160
nherriot 0:bcf2aa85d7f9 161 cmd[0] = addr;
nherriot 0:bcf2aa85d7f9 162 cmd[1] = data; // New value of the register
nherriot 0:bcf2aa85d7f9 163 m_i2c.write(MMA8452_ADDRESS, cmd, 2);
nherriot 0:bcf2aa85d7f9 164
nherriot 0:bcf2aa85d7f9 165 cmd[0] = MODE_STATUS;
nherriot 0:bcf2aa85d7f9 166 cmd[1] = 0x01; // Active Mode on
nherriot 0:bcf2aa85d7f9 167 m_i2c.write(MMA8452_ADDRESS, cmd, 2);
nherriot 0:bcf2aa85d7f9 168
nherriot 0:bcf2aa85d7f9 169 }
nherriot 0:bcf2aa85d7f9 170
nherriot 0:bcf2aa85d7f9 171
nherriot 0:bcf2aa85d7f9 172
nherriot 0:bcf2aa85d7f9 173 // Read from specified MMA7660FC register
nherriot 0:bcf2aa85d7f9 174 char Accelerometer_MMA8452::read_reg(char addr)
nherriot 0:bcf2aa85d7f9 175 {
nherriot 0:bcf2aa85d7f9 176
nherriot 0:bcf2aa85d7f9 177 m_i2c.start(); // Start
nherriot 0:bcf2aa85d7f9 178 m_i2c.write(0x98); // A write to device 0x98
nherriot 0:bcf2aa85d7f9 179 m_i2c.write(addr); // Register to read
nherriot 0:bcf2aa85d7f9 180 m_i2c.start();
nherriot 0:bcf2aa85d7f9 181 m_i2c.write(0x99); // Read from device 0x99
nherriot 0:bcf2aa85d7f9 182 char c = m_i2c.read(0); // Read the data
nherriot 0:bcf2aa85d7f9 183 m_i2c.stop();
nherriot 0:bcf2aa85d7f9 184
nherriot 0:bcf2aa85d7f9 185 return c;
nherriot 0:bcf2aa85d7f9 186
nherriot 0:bcf2aa85d7f9 187 }
nherriot 0:bcf2aa85d7f9 188
nherriot 0:bcf2aa85d7f9 189
nherriot 0:bcf2aa85d7f9 190
nherriot 0:bcf2aa85d7f9 191
nherriot 0:bcf2aa85d7f9 192
nherriot 0:bcf2aa85d7f9 193