Ashley Mills / MMA8452

Library for driving the MMA8452 accelerometer over I2C

Dependents:   MMA8452_Test MMA8452_Demo Dualing_Tanks IMU-Controlled_MP3_Player ... more

Here is a simple example:

#include "mbed.h"
#include "MMA8452.h"

int main() {
   Serial pc(USBTX,USBRX);
   pc.baud(115200);
   double x = 0, y = 0, z = 0;

   MMA8452 acc(p28, p27, 40000);
   acc.setBitDepth(MMA8452::BIT_DEPTH_12);
   acc.setDynamicRange(MMA8452::DYNAMIC_RANGE_4G);
   acc.setDataRate(MMA8452::RATE_100);
   
   while(1) {
      if(!acc.isXYZReady()) {
         wait(0.01);
         continue;
      }
      acc.readXYZGravity(&x,&y,&z);
      pc.printf("Gravities: %lf %lf %lf\r\n",x,y,z);
   }
}

An easy way to test that this actually works is to run the loop above and hold the MMA8452 parallel to the ground along the respective axis (and upsidedown in each axis). You will see 1G on the respective axis and 0G on the others.

MMA8452.h@1:ef026bf28798, 2013-10-08 (annotated)

Committer:
nherriot
Date:
Tue Oct 08 15:25:32 2013 +0000
Revision:
1:ef026bf28798
Parent:
0:bcf2aa85d7f9
Child:
2:66db0f91b215
adding device id method detection

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 // the SparkFun breakout board defaults to 1, set to 0 if SA0 jumper on the bottom of the board is set
nherriot 0:bcf2aa85d7f9 21 // see the Table 10. I2C Device Address Sequence in Freescale MMA8452Q pdf
nherriot 0:bcf2aa85d7f9 22
nherriot 0:bcf2aa85d7f9 23 //#define SA0 1
nherriot 0:bcf2aa85d7f9 24 //#if SA0
nherriot 0:bcf2aa85d7f9 25 //#define MMA8452_ADDRESS 0x3A // SA0 is high, 0x1C if low - it should be 0x1D, but we shift now to save shifting in the code
nherriot 0:bcf2aa85d7f9 26 //#else
nherriot 0:bcf2aa85d7f9 27 //#define MMA8452_ADDRESS 0x1C
nherriot 0:bcf2aa85d7f9 28 //#endif
nherriot 0:bcf2aa85d7f9 29
nherriot 0:bcf2aa85d7f9 30 //#ifndef MBED_MMA8452
nherriot 0:bcf2aa85d7f9 31
nherriot 0:bcf2aa85d7f9 32 //#define MBED_MMA8452
nherriot 0:bcf2aa85d7f9 33
nherriot 0:bcf2aa85d7f9 34 #include "mbed.h"
nherriot 0:bcf2aa85d7f9 35
nherriot 0:bcf2aa85d7f9 36 /** Accelerometer MMA8452 class
nherriot 0:bcf2aa85d7f9 37 *
nherriot 0:bcf2aa85d7f9 38 * Example:
nherriot 0:bcf2aa85d7f9 39 * @code
nherriot 0:bcf2aa85d7f9 40 *
nherriot 0:bcf2aa85d7f9 41 * #include "mbed.h"
nherriot 0:bcf2aa85d7f9 42 * #include "MMA8452.h"
nherriot 0:bcf2aa85d7f9 43 *
nherriot 0:bcf2aa85d7f9 44 *
nherriot 0:bcf2aa85d7f9 45 * Accelerometer_MMA8452 Acc(p28, p27);
nherriot 0:bcf2aa85d7f9 46 * serial pc(USBTX, USBRX);
nherriot 0:bcf2aa85d7f9 47 *
nherriot 0:bcf2aa85d7f9 48 * int main()
nherriot 0:bcf2aa85d7f9 49 * {
nherriot 0:bcf2aa85d7f9 50 * Acc.init();
nherriot 0:bcf2aa85d7f9 51 * while(1)
nherriot 0:bcf2aa85d7f9 52 * {
nherriot 0:bcf2aa85d7f9 53 * int x=0, y=0, z=0;
nherriot 0:bcf2aa85d7f9 54 * Acc.read_Tilt(&x, &y, &z);
nherriot 0:bcf2aa85d7f9 55 * pc.printf("Tilt x: %2.2f degree \n", x); // Print the tilt orientation of the X axis
nherriot 0:bcf2aa85d7f9 56 * pc.printf("Tilt y: %2.2f degree \n", y); // Print the tilt orientation of the Y axis
nherriot 0:bcf2aa85d7f9 57 * pc.printf("Tilt z: %2.2f degree \n", z); // Print the tilt orientation of the Z axis
nherriot 0:bcf2aa85d7f9 58 * wait(1);
nherriot 0:bcf2aa85d7f9 59 * }
nherriot 0:bcf2aa85d7f9 60 * }
nherriot 0:bcf2aa85d7f9 61 * @endcode
nherriot 0:bcf2aa85d7f9 62 */
nherriot 0:bcf2aa85d7f9 63
nherriot 0:bcf2aa85d7f9 64 // More info on MCU Master address can be found on section 5.10.1 of http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MMA8452Q
nherriot 0:bcf2aa85d7f9 65 #define SA0 1
nherriot 0:bcf2aa85d7f9 66 #if SA0
nherriot 0:bcf2aa85d7f9 67 #define MMA8452_ADDRESS 0x1D // SA0 is high, 0x1C if low -
nherriot 0:bcf2aa85d7f9 68 #else
nherriot 0:bcf2aa85d7f9 69 #define MMA8452_ADDRESS 0x1C
nherriot 0:bcf2aa85d7f9 70 #endif
nherriot 0:bcf2aa85d7f9 71
nherriot 0:bcf2aa85d7f9 72 // Register descriptions found in section 6 of pdf
nherriot 0:bcf2aa85d7f9 73 #define STATUS 0x00 // Type 'read' : Real time status, should return 0x00
nherriot 0:bcf2aa85d7f9 74 #define OUT_X_MSB 0x01 // Type 'read' : x axis - 8 most significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 75 #define OUT_X_LSB 0x02 // Type 'read' : x axis - 4 least significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 76 #define OUT_Y_MSB 0x03 // Type 'read' : y axis - 8 most significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 77 #define OUT_Y_LSB 0x04 // Type 'read' : y axis - 4 least significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 78 #define OUT_Z_MSB 0x05 // Type 'read' : z axis - 8 most significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 79 #define OUT_Z_LSB 0x06 // Type 'read' : z axis - 4 least significatn bit of a 12 bit sample
nherriot 0:bcf2aa85d7f9 80
nherriot 0:bcf2aa85d7f9 81 #define SYSMOD 0x0B // Type 'read' : This tells you if device is active, sleep or standy 0x00=STANDBY 0x01=WAKE 0x02=SLEEP
nherriot 0:bcf2aa85d7f9 82 #define WHO_AM_I 0x0D // Type 'read' : This should return the device id of 0x2A
nherriot 0:bcf2aa85d7f9 83
nherriot 0:bcf2aa85d7f9 84 #define PL_STATUS 0x10 // Type 'read' : This shows portrait landscape mode orientation
nherriot 0:bcf2aa85d7f9 85 #define PL_CFG 0x11 // Type 'read/write' : This allows portrait landscape configuration
nherriot 0:bcf2aa85d7f9 86 #define PL_COUNT 0x12 // Type 'read' : This is the portraint landscape debounce counter
nherriot 0:bcf2aa85d7f9 87 #define PL_BF_ZCOMP 0x13 // Type 'read' :
nherriot 0:bcf2aa85d7f9 88 #define PL_THS_REG 0x14 // Type 'read' :
nherriot 0:bcf2aa85d7f9 89
nherriot 0:bcf2aa85d7f9 90 #define FF_MT_CFG 0X15 // Type 'read/write' : Freefaul motion functional block configuration
nherriot 0:bcf2aa85d7f9 91 #define FF_MT_SRC 0X16 // Type 'read' : Freefaul motion event source register
nherriot 1:ef026bf28798 92 #define FF_MT_THS 0X17 // Type 'read' : Freefaul motion threshold register
nherriot 0:bcf2aa85d7f9 93 #define FF_COUNT 0X18 // Type 'read' : Freefaul motion debouce counter
nherriot 0:bcf2aa85d7f9 94
nherriot 0:bcf2aa85d7f9 95 #define ASLP_COUNT 0x29 // Type 'read/write' : Counter setting for auto sleep
nherriot 0:bcf2aa85d7f9 96 #define CTRL_REG_1 0x2A // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 97 #define CTRL_REG_2 0x2B // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 98 #define CTRL_REG_3 0x2C // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 99 #define CTRL_REG_4 0x2D // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 100 #define CTRL_REG_5 0x2E // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 101
nherriot 0:bcf2aa85d7f9 102
nherriot 0:bcf2aa85d7f9 103
nherriot 0:bcf2aa85d7f9 104 #define TILT_STATUS 0x03 // Tilt Status (Read only)
nherriot 0:bcf2aa85d7f9 105 #define SRST_STATUS 0x04 // Sample Rate Status Register (Read only)
nherriot 0:bcf2aa85d7f9 106 #define SPCNT_STATUS 0x05 // Sleep Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 107 #define INTSU_STATUS 0x06 // Interrupt Setup Register
nherriot 0:bcf2aa85d7f9 108 #define MODE_STATUS 0x07 // Mode Register (Read/Write)
nherriot 0:bcf2aa85d7f9 109 #define SR_STATUS 0x08 // Auto-Wake and Active Mode Portrait/Landscape Samples per Seconds Register (Read/Write)
nherriot 0:bcf2aa85d7f9 110 #define PDET_STATUS 0x09 // Tap/Pulse Detection Register (Read/Write)
nherriot 0:bcf2aa85d7f9 111 #define PD_STATUS 0xA // Tap/Pulse Debounce Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 112
nherriot 0:bcf2aa85d7f9 113
nherriot 0:bcf2aa85d7f9 114
nherriot 0:bcf2aa85d7f9 115
nherriot 0:bcf2aa85d7f9 116
nherriot 0:bcf2aa85d7f9 117
nherriot 0:bcf2aa85d7f9 118 class Accelerometer_MMA8452
nherriot 0:bcf2aa85d7f9 119 {
nherriot 0:bcf2aa85d7f9 120 public:
nherriot 0:bcf2aa85d7f9 121
nherriot 0:bcf2aa85d7f9 122
nherriot 0:bcf2aa85d7f9 123 /** Create an accelerometer object connected to the specified I2C object
nherriot 0:bcf2aa85d7f9 124 *
nherriot 0:bcf2aa85d7f9 125 * @param sda I2C data port
nherriot 0:bcf2aa85d7f9 126 * @param scl I2C8452 clock port
nherriot 0:bcf2aa85d7f9 127 *
nherriot 0:bcf2aa85d7f9 128 */
nherriot 1:ef026bf28798 129 Accelerometer_MMA8452(PinName sda, PinName scl, int frequency);
nherriot 1:ef026bf28798 130 //Accelerometer_MMA8452(PinName sda, PinName scl);
nherriot 0:bcf2aa85d7f9 131
nherriot 0:bcf2aa85d7f9 132 /** Destroys an MMA8452 object
nherriot 0:bcf2aa85d7f9 133 *
nherriot 0:bcf2aa85d7f9 134 */
nherriot 0:bcf2aa85d7f9 135 ~Accelerometer_MMA8452();
nherriot 0:bcf2aa85d7f9 136
nherriot 0:bcf2aa85d7f9 137 /** Activate the MMA8452 (required)
nherriot 1:ef026bf28798 138 * returns 0 for success in activating the chip
nherriot 1:ef026bf28798 139 * returns 1 for failure in activating the chip
nherriot 1:ef026bf28798 140 * -currrently no retries or waiting is done, this method tries 1 time the exits.
nherriot 1:ef026bf28798 141 */
nherriot 0:bcf2aa85d7f9 142 int activate();
nherriot 0:bcf2aa85d7f9 143
nherriot 0:bcf2aa85d7f9 144 /** Initialization of device MMA8452 (required)
nherriot 0:bcf2aa85d7f9 145 */
nherriot 0:bcf2aa85d7f9 146 void init();
nherriot 0:bcf2aa85d7f9 147
nherriot 1:ef026bf28798 148 /** Read the device ID from the accelerometer
nherriot 1:ef026bf28798 149 *
nherriot 1:ef026bf28798 150 * @param *deviceID Value of device - is should be 0x2A
nherriot 1:ef026bf28798 151 * return 0 for success or
nherriot 1:ef026bf28798 152 * return 1 for failure.
nherriot 1:ef026bf28798 153 */
nherriot 1:ef026bf28798 154 int Get_DeviceID(int *deviceID);
nherriot 0:bcf2aa85d7f9 155 /** Read the Tilt Angle using Three Axis
nherriot 0:bcf2aa85d7f9 156 *
nherriot 0:bcf2aa85d7f9 157 * @param *x Value of x tilt
nherriot 0:bcf2aa85d7f9 158 * @param *y Value of y tilt
nherriot 0:bcf2aa85d7f9 159 * @param *z Value of z tilt
nherriot 0:bcf2aa85d7f9 160 */
nherriot 0:bcf2aa85d7f9 161 void read_Tilt(float *x, float *y, float *z);
nherriot 0:bcf2aa85d7f9 162
nherriot 0:bcf2aa85d7f9 163 /** Read the x register of the MMA8452
nherriot 0:bcf2aa85d7f9 164 *
nherriot 0:bcf2aa85d7f9 165 * @returns The value of x acceleration
nherriot 0:bcf2aa85d7f9 166 */
nherriot 0:bcf2aa85d7f9 167 int read_x();
nherriot 0:bcf2aa85d7f9 168
nherriot 0:bcf2aa85d7f9 169 /** Read the y register of the MMA8452
nherriot 0:bcf2aa85d7f9 170 *
nherriot 0:bcf2aa85d7f9 171 * @returns The value of y acceleration
nherriot 0:bcf2aa85d7f9 172 */
nherriot 0:bcf2aa85d7f9 173 int read_y();
nherriot 0:bcf2aa85d7f9 174
nherriot 0:bcf2aa85d7f9 175 /** Read the z register of the MMA8452
nherriot 0:bcf2aa85d7f9 176 *
nherriot 0:bcf2aa85d7f9 177 * @returns The value of z acceleration
nherriot 0:bcf2aa85d7f9 178 */
nherriot 0:bcf2aa85d7f9 179 int read_z();
nherriot 1:ef026bf28798 180
nherriot 1:ef026bf28798 181 /** Read the x,y and z registers of the MMA8452
nherriot 1:ef026bf28798 182 *
nherriot 1:ef026bf28798 183 * takes a 2 byte char buffer to store the value
nherriot 1:ef026bf28798 184 * for each axis.
nherriot 1:ef026bf28798 185 * returns 0 for success, and 1 for failure
nherriot 1:ef026bf28798 186 *
nherriot 1:ef026bf28798 187 */
nherriot 1:ef026bf28798 188 int read_xyz(char *x, char *y, char *z);
nherriot 0:bcf2aa85d7f9 189
nherriot 0:bcf2aa85d7f9 190 /** Read from specified MMA8452 register
nherriot 0:bcf2aa85d7f9 191 *
nherriot 0:bcf2aa85d7f9 192 * @param addr The internal registeraddress of the MMA8452
nherriot 0:bcf2aa85d7f9 193 * @returns The value of the register
nherriot 0:bcf2aa85d7f9 194 */
nherriot 0:bcf2aa85d7f9 195 char read_reg(char addr);
nherriot 0:bcf2aa85d7f9 196
nherriot 0:bcf2aa85d7f9 197 /** Write to specified MMA8452 register
nherriot 0:bcf2aa85d7f9 198 *
nherriot 0:bcf2aa85d7f9 199 * @param addr The internal registeraddress of the MMA8452
nherriot 0:bcf2aa85d7f9 200 * @param data New value of the register
nherriot 0:bcf2aa85d7f9 201 */
nherriot 0:bcf2aa85d7f9 202 void write_reg(char addr, char data);
nherriot 0:bcf2aa85d7f9 203
nherriot 0:bcf2aa85d7f9 204
nherriot 0:bcf2aa85d7f9 205 private:
nherriot 0:bcf2aa85d7f9 206 I2C m_i2c;
nherriot 1:ef026bf28798 207 int m_frequency;
nherriot 0:bcf2aa85d7f9 208
nherriot 0:bcf2aa85d7f9 209 };
nherriot 0:bcf2aa85d7f9 210
nherriot 0:bcf2aa85d7f9 211 //#endif