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@3:ffb0b1650ca2, 2013-10-16 (annotated)

Committer:
nherriot
Date:
Wed Oct 16 14:11:04 2013 +0000
Revision:
3:ffb0b1650ca2
Parent:
2:66db0f91b215
Child:
5:b3d0abd97e55
mma8452 0.1 - basic functions supported. ; Still going under test.

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 3:ffb0b1650ca2 95 #define ASLP_COUNT 0x29 // Type 'read/write' : Counter settings 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 3:ffb0b1650ca2 102 // Defined in table 13 of the Freescale PDF
nherriot 3:ffb0b1650ca2 103 #define STANDBY 0x00 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 104 #define WAKE 0x01 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 105 #define SLEEP 0x02 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 106 #define ACTIVE 0x01 // Stage value returned and set in Control Register 1, it can be STANDBY=00, or ACTIVE=01
nherriot 3:ffb0b1650ca2 107
nherriot 0:bcf2aa85d7f9 108
nherriot 0:bcf2aa85d7f9 109
nherriot 0:bcf2aa85d7f9 110 #define TILT_STATUS 0x03 // Tilt Status (Read only)
nherriot 0:bcf2aa85d7f9 111 #define SRST_STATUS 0x04 // Sample Rate Status Register (Read only)
nherriot 0:bcf2aa85d7f9 112 #define SPCNT_STATUS 0x05 // Sleep Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 113 #define INTSU_STATUS 0x06 // Interrupt Setup Register
nherriot 0:bcf2aa85d7f9 114 #define MODE_STATUS 0x07 // Mode Register (Read/Write)
nherriot 0:bcf2aa85d7f9 115 #define SR_STATUS 0x08 // Auto-Wake and Active Mode Portrait/Landscape Samples per Seconds Register (Read/Write)
nherriot 0:bcf2aa85d7f9 116 #define PDET_STATUS 0x09 // Tap/Pulse Detection Register (Read/Write)
nherriot 0:bcf2aa85d7f9 117 #define PD_STATUS 0xA // Tap/Pulse Debounce Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 118
nherriot 0:bcf2aa85d7f9 119
nherriot 0:bcf2aa85d7f9 120
nherriot 0:bcf2aa85d7f9 121
nherriot 0:bcf2aa85d7f9 122
nherriot 0:bcf2aa85d7f9 123
nherriot 0:bcf2aa85d7f9 124 class Accelerometer_MMA8452
nherriot 0:bcf2aa85d7f9 125 {
nherriot 0:bcf2aa85d7f9 126 public:
nherriot 0:bcf2aa85d7f9 127
nherriot 0:bcf2aa85d7f9 128
nherriot 0:bcf2aa85d7f9 129 /** Create an accelerometer object connected to the specified I2C object
nherriot 0:bcf2aa85d7f9 130 *
nherriot 0:bcf2aa85d7f9 131 * @param sda I2C data port
nherriot 0:bcf2aa85d7f9 132 * @param scl I2C8452 clock port
nherriot 0:bcf2aa85d7f9 133 *
nherriot 0:bcf2aa85d7f9 134 */
nherriot 1:ef026bf28798 135 Accelerometer_MMA8452(PinName sda, PinName scl, int frequency);
nherriot 1:ef026bf28798 136 //Accelerometer_MMA8452(PinName sda, PinName scl);
nherriot 0:bcf2aa85d7f9 137
nherriot 0:bcf2aa85d7f9 138 /** Destroys an MMA8452 object
nherriot 0:bcf2aa85d7f9 139 *
nherriot 0:bcf2aa85d7f9 140 */
nherriot 0:bcf2aa85d7f9 141 ~Accelerometer_MMA8452();
nherriot 0:bcf2aa85d7f9 142
nherriot 3:ffb0b1650ca2 143
nherriot 3:ffb0b1650ca2 144
nherriot 3:ffb0b1650ca2 145 /** Get system mode of the MMA8452 (not required)
nherriot 3:ffb0b1650ca2 146 * returns 0 for success in reading the system mode of the chip
nherriot 3:ffb0b1650ca2 147 * returns 1 for failure in reading the system mode of the chip
nherriot 3:ffb0b1650ca2 148 * -currently no retries or waiting is done, this method tries 1 time then exits.
nherriot 3:ffb0b1650ca2 149 *
nherriot 3:ffb0b1650ca2 150 * This method is used to find out the system mode of the chip ACTIVE = 0x00 or STANDBY = 0x01
nherriot 3:ffb0b1650ca2 151 */
nherriot 3:ffb0b1650ca2 152 int get_SystemMode(int& deviceSystemMode);
nherriot 3:ffb0b1650ca2 153
nherriot 3:ffb0b1650ca2 154
nherriot 3:ffb0b1650ca2 155
nherriot 3:ffb0b1650ca2 156 /** Get status of the MMA8452 (not required)
nherriot 3:ffb0b1650ca2 157 * returns 0 for success in reading the status of the chip
nherriot 3:ffb0b1650ca2 158 * returns 1 for failure in reading the status of the chip
nherriot 3:ffb0b1650ca2 159 * -currrently no retries or waiting is done, this method tries 1 time then exits.
nherriot 3:ffb0b1650ca2 160 *
nherriot 3:ffb0b1650ca2 161 * This method is used to find out the real time status of the device it shows if
nherriot 3:ffb0b1650ca2 162 * x,y and z values have been overwritten before they have been read since a change happened.
nherriot 3:ffb0b1650ca2 163 *
nherriot 3:ffb0b1650ca2 164 */
nherriot 3:ffb0b1650ca2 165 int get_Status(int& deviceStatus);
nherriot 3:ffb0b1650ca2 166
nherriot 3:ffb0b1650ca2 167
nherriot 3:ffb0b1650ca2 168
nherriot 0:bcf2aa85d7f9 169 /** Activate the MMA8452 (required)
nherriot 1:ef026bf28798 170 * returns 0 for success in activating the chip
nherriot 1:ef026bf28798 171 * returns 1 for failure in activating the chip
nherriot 1:ef026bf28798 172 * -currrently no retries or waiting is done, this method tries 1 time the exits.
nherriot 3:ffb0b1650ca2 173 *
nherriot 3:ffb0b1650ca2 174 * This will set the device 'active' even if it's already active. It's just a way to force that state.
nherriot 1:ef026bf28798 175 */
nherriot 0:bcf2aa85d7f9 176 int activate();
nherriot 3:ffb0b1650ca2 177
nherriot 3:ffb0b1650ca2 178
nherriot 3:ffb0b1650ca2 179
nherriot 3:ffb0b1650ca2 180 /** Standby the MMA8452 (not required)
nherriot 3:ffb0b1650ca2 181 * returns 0 for success in activating the chip
nherriot 3:ffb0b1650ca2 182 * returns 1 for failure in activating the chip
nherriot 3:ffb0b1650ca2 183 * -currrently no retries or waiting is done, this method tries 1 time the exits.
nherriot 3:ffb0b1650ca2 184 *
nherriot 3:ffb0b1650ca2 185 * This will set the device 'standby' even if it's already in standby. It's just a way to force that state.
nherriot 3:ffb0b1650ca2 186 */
nherriot 3:ffb0b1650ca2 187 int standby();
nherriot 3:ffb0b1650ca2 188
nherriot 3:ffb0b1650ca2 189
nherriot 0:bcf2aa85d7f9 190
nherriot 0:bcf2aa85d7f9 191 /** Initialization of device MMA8452 (required)
nherriot 0:bcf2aa85d7f9 192 */
nherriot 0:bcf2aa85d7f9 193 void init();
nherriot 0:bcf2aa85d7f9 194
nherriot 1:ef026bf28798 195 /** Read the device ID from the accelerometer
nherriot 1:ef026bf28798 196 *
nherriot 1:ef026bf28798 197 * @param *deviceID Value of device - is should be 0x2A
nherriot 1:ef026bf28798 198 * return 0 for success or
nherriot 1:ef026bf28798 199 * return 1 for failure.
nherriot 1:ef026bf28798 200 */
nherriot 3:ffb0b1650ca2 201 int get_DeviceID(int& deviceID);
nherriot 0:bcf2aa85d7f9 202
nherriot 3:ffb0b1650ca2 203 int read_y();
nherriot 3:ffb0b1650ca2 204
nherriot 3:ffb0b1650ca2 205 int read_z();
nherriot 3:ffb0b1650ca2 206
nherriot 0:bcf2aa85d7f9 207 /** Read the x register of the MMA8452
nherriot 0:bcf2aa85d7f9 208 *
nherriot 0:bcf2aa85d7f9 209 * @returns The value of x acceleration
nherriot 0:bcf2aa85d7f9 210 */
nherriot 3:ffb0b1650ca2 211 int read_x_raw(char *xaxis);
nherriot 3:ffb0b1650ca2 212 //int read_x(int& xaxisLSB);
nherriot 0:bcf2aa85d7f9 213 /** Read the y register of the MMA8452
nherriot 0:bcf2aa85d7f9 214 *
nherriot 0:bcf2aa85d7f9 215 * @returns The value of y acceleration
nherriot 0:bcf2aa85d7f9 216 */
nherriot 3:ffb0b1650ca2 217 int read_y_raw(char *yaxis);
nherriot 0:bcf2aa85d7f9 218
nherriot 0:bcf2aa85d7f9 219 /** Read the z register of the MMA8452
nherriot 0:bcf2aa85d7f9 220 *
nherriot 0:bcf2aa85d7f9 221 * @returns The value of z acceleration
nherriot 0:bcf2aa85d7f9 222 */
nherriot 3:ffb0b1650ca2 223 int read_z_raw(char * zaxis);
nherriot 1:ef026bf28798 224
nherriot 1:ef026bf28798 225 /** Read the x,y and z registers of the MMA8452
nherriot 1:ef026bf28798 226 *
nherriot 1:ef026bf28798 227 * takes a 2 byte char buffer to store the value
nherriot 1:ef026bf28798 228 * for each axis.
nherriot 1:ef026bf28798 229 * returns 0 for success, and 1 for failure
nherriot 1:ef026bf28798 230 *
nherriot 1:ef026bf28798 231 */
nherriot 1:ef026bf28798 232 int read_xyz(char *x, char *y, char *z);
nherriot 0:bcf2aa85d7f9 233
nherriot 0:bcf2aa85d7f9 234 /** Read from specified MMA8452 register
nherriot 0:bcf2aa85d7f9 235 *
nherriot 0:bcf2aa85d7f9 236 * @param addr The internal registeraddress of the MMA8452
nherriot 0:bcf2aa85d7f9 237 * @returns The value of the register
nherriot 0:bcf2aa85d7f9 238 */
nherriot 0:bcf2aa85d7f9 239 char read_reg(char addr);
nherriot 0:bcf2aa85d7f9 240
nherriot 0:bcf2aa85d7f9 241 /** Write to specified MMA8452 register
nherriot 0:bcf2aa85d7f9 242 *
nherriot 0:bcf2aa85d7f9 243 * @param addr The internal registeraddress of the MMA8452
nherriot 0:bcf2aa85d7f9 244 * @param data New value of the register
nherriot 0:bcf2aa85d7f9 245 */
nherriot 0:bcf2aa85d7f9 246 void write_reg(char addr, char data);
nherriot 0:bcf2aa85d7f9 247
nherriot 0:bcf2aa85d7f9 248
nherriot 0:bcf2aa85d7f9 249 private:
nherriot 0:bcf2aa85d7f9 250 I2C m_i2c;
nherriot 1:ef026bf28798 251 int m_frequency;
nherriot 0:bcf2aa85d7f9 252
nherriot 0:bcf2aa85d7f9 253 };
nherriot 0:bcf2aa85d7f9 254
nherriot 0:bcf2aa85d7f9 255 //#endif