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@17:6e4232c421c0, 2014-03-05 (annotated)

Committer:
ashleymills
Date:
Wed Mar 05 17:01:00 2014 +0000
Revision:
17:6e4232c421c0
Parent:
16:d6dde2318edc
Child:
18:27d839e6dc0e
Cleaned up debug handling

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ashleymills 15:7620a11149b8 1 #pragma once
ashleymills 15:7620a11149b8 2
ashleymills 14:0602b45ca70f 3 // Authors: Ashley Mills, Nicholas Herriot
nherriot 0:bcf2aa85d7f9 4 /* Copyright (c) 2013 Vodafone, MIT License
nherriot 0:bcf2aa85d7f9 5 *
nherriot 0:bcf2aa85d7f9 6 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
nherriot 0:bcf2aa85d7f9 7 * and associated documentation files (the "Software"), to deal in the Software without restriction,
nherriot 0:bcf2aa85d7f9 8 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
nherriot 0:bcf2aa85d7f9 9 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
nherriot 0:bcf2aa85d7f9 10 * furnished to do so, subject to the following conditions:
nherriot 0:bcf2aa85d7f9 11 *
nherriot 0:bcf2aa85d7f9 12 * The above copyright notice and this permission notice shall be included in all copies or
nherriot 0:bcf2aa85d7f9 13 * substantial portions of the Software.
nherriot 0:bcf2aa85d7f9 14 *
nherriot 0:bcf2aa85d7f9 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
nherriot 0:bcf2aa85d7f9 16 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
nherriot 0:bcf2aa85d7f9 17 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
nherriot 0:bcf2aa85d7f9 18 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
nherriot 0:bcf2aa85d7f9 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nherriot 0:bcf2aa85d7f9 20 */
nherriot 0:bcf2aa85d7f9 21
nherriot 0:bcf2aa85d7f9 22 // the SparkFun breakout board defaults to 1, set to 0 if SA0 jumper on the bottom of the board is set
nherriot 0:bcf2aa85d7f9 23 // see the Table 10. I2C Device Address Sequence in Freescale MMA8452Q pdf
nherriot 0:bcf2aa85d7f9 24
ashleymills 15:7620a11149b8 25 #include "mbed.h"
nherriot 0:bcf2aa85d7f9 26
nherriot 0:bcf2aa85d7f9 27 // 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 28 #define SA0 1
nherriot 0:bcf2aa85d7f9 29 #if SA0
ashleymills 11:dfd1e0afcb7b 30 #define MMA8452_ADDRESS 0x3A // 0x1D<<1 // SA0 is high, 0x1C if low -
nherriot 0:bcf2aa85d7f9 31 #else
ashleymills 11:dfd1e0afcb7b 32 #define MMA8452_ADDRESS 0x38 // 0x1C<<1
nherriot 0:bcf2aa85d7f9 33 #endif
nherriot 0:bcf2aa85d7f9 34
nherriot 0:bcf2aa85d7f9 35 // Register descriptions found in section 6 of pdf
ashleymills 12:172540ff6b8b 36 #define MMA8452_STATUS 0x00 // Type 'read' : Status of the data registers
ashleymills 12:172540ff6b8b 37 #define MMA8452_OUT_X_MSB 0x01 // Type 'read' : x axis - MSB of 2 byte sample
ashleymills 12:172540ff6b8b 38 #define MMA8452_OUT_X_LSB 0x02 // Type 'read' : x axis - LSB of 2 byte sample
ashleymills 12:172540ff6b8b 39 #define MMA8452_OUT_Y_MSB 0x03 // Type 'read' : y axis - MSB of 2 byte sample
ashleymills 12:172540ff6b8b 40 #define MMA8452_OUT_Y_LSB 0x04 // Type 'read' : y axis - LSB of 2 byte sample
ashleymills 12:172540ff6b8b 41 #define MMA8452_OUT_Z_MSB 0x05 // Type 'read' : z axis - MSB of 2 byte sample
ashleymills 12:172540ff6b8b 42 #define MMA8452_OUT_Z_LSB 0x06 // Type 'read' : z axis - LSB of 2 byte sample
nherriot 0:bcf2aa85d7f9 43
ashleymills 12:172540ff6b8b 44 // register definitions
ashleymills 12:172540ff6b8b 45 #define MMA8452_XYZ_DATA_CFG 0x0E
ashleymills 12:172540ff6b8b 46
ashleymills 12:172540ff6b8b 47 #define MMA8452_SYSMOD 0x0B // Type 'read' : This tells you if device is active, sleep or standy 0x00=STANDBY 0x01=WAKE 0x02=SLEEP
ashleymills 12:172540ff6b8b 48 #define MMA8452_WHO_AM_I 0x0D // Type 'read' : This should return the device id of 0x2A
nherriot 0:bcf2aa85d7f9 49
ashleymills 12:172540ff6b8b 50 #define MMA8452_PL_STATUS 0x10 // Type 'read' : This shows portrait landscape mode orientation
ashleymills 12:172540ff6b8b 51 #define MMA8452_PL_CFG 0x11 // Type 'read/write' : This allows portrait landscape configuration
ashleymills 12:172540ff6b8b 52 #define MMA8452_PL_COUNT 0x12 // Type 'read' : This is the portraint landscape debounce counter
ashleymills 12:172540ff6b8b 53 #define MMA8452_PL_BF_ZCOMP 0x13 // Type 'read' :
ashleymills 12:172540ff6b8b 54 #define MMA8452_PL_THS_REG 0x14 // Type 'read' :
nherriot 0:bcf2aa85d7f9 55
ashleymills 12:172540ff6b8b 56 #define MMA8452_FF_MT_CFG 0X15 // Type 'read/write' : Freefaul motion functional block configuration
ashleymills 12:172540ff6b8b 57 #define MMA8452_FF_MT_SRC 0X16 // Type 'read' : Freefaul motion event source register
ashleymills 12:172540ff6b8b 58 #define MMA8452_FF_MT_THS 0X17 // Type 'read' : Freefaul motion threshold register
ashleymills 12:172540ff6b8b 59 #define MMA8452_FF_COUNT 0X18 // Type 'read' : Freefaul motion debouce counter
nherriot 0:bcf2aa85d7f9 60
ashleymills 12:172540ff6b8b 61 #define MMA8452_ASLP_COUNT 0x29 // Type 'read/write' : Counter settings for auto sleep
ashleymills 12:172540ff6b8b 62 #define MMA8452_CTRL_REG_1 0x2A // Type 'read/write' :
ashleymills 12:172540ff6b8b 63 #define MMA8452_CTRL_REG_2 0x2B // Type 'read/write' :
ashleymills 12:172540ff6b8b 64 #define MMA8452_CTRL_REG_3 0x2C // Type 'read/write' :
ashleymills 12:172540ff6b8b 65 #define MMA8452_CTRL_REG_4 0x2D // Type 'read/write' :
ashleymills 12:172540ff6b8b 66 #define MMA8452_CTRL_REG_5 0x2E // Type 'read/write' :
nherriot 0:bcf2aa85d7f9 67
nherriot 3:ffb0b1650ca2 68 // Defined in table 13 of the Freescale PDF
ashleymills 12:172540ff6b8b 69 /// xxx these all need to have better names
nherriot 3:ffb0b1650ca2 70 #define STANDBY 0x00 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 71 #define WAKE 0x01 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 72 #define SLEEP 0x02 // State value returned after a SYSMOD request, it can be in state STANDBY, WAKE or SLEEP
nherriot 3:ffb0b1650ca2 73 #define ACTIVE 0x01 // Stage value returned and set in Control Register 1, it can be STANDBY=00, or ACTIVE=01
nherriot 0:bcf2aa85d7f9 74
nherriot 0:bcf2aa85d7f9 75 #define TILT_STATUS 0x03 // Tilt Status (Read only)
nherriot 0:bcf2aa85d7f9 76 #define SRST_STATUS 0x04 // Sample Rate Status Register (Read only)
nherriot 0:bcf2aa85d7f9 77 #define SPCNT_STATUS 0x05 // Sleep Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 78 #define INTSU_STATUS 0x06 // Interrupt Setup Register
nherriot 0:bcf2aa85d7f9 79 #define MODE_STATUS 0x07 // Mode Register (Read/Write)
nherriot 0:bcf2aa85d7f9 80 #define SR_STATUS 0x08 // Auto-Wake and Active Mode Portrait/Landscape Samples per Seconds Register (Read/Write)
nherriot 0:bcf2aa85d7f9 81 #define PDET_STATUS 0x09 // Tap/Pulse Detection Register (Read/Write)
nherriot 0:bcf2aa85d7f9 82 #define PD_STATUS 0xA // Tap/Pulse Debounce Count Register (Read/Write)
nherriot 0:bcf2aa85d7f9 83
ashleymills 12:172540ff6b8b 84 // masks for enabling/disabling standby
ashleymills 11:dfd1e0afcb7b 85 #define MMA8452_ACTIVE_MASK 0x01
ashleymills 11:dfd1e0afcb7b 86 #define MMA8452_STANDBY_MASK 0xFE
ashleymills 11:dfd1e0afcb7b 87
ashleymills 12:172540ff6b8b 88 // mask for dynamic range reading and writing
ashleymills 11:dfd1e0afcb7b 89 #define MMA8452_DYNAMIC_RANGE_MASK 0xFC
ashleymills 11:dfd1e0afcb7b 90
ashleymills 12:172540ff6b8b 91 // mask and shift for data rate reading and writing
ashleymills 11:dfd1e0afcb7b 92 #define MMA8452_DATA_RATE_MASK 0xC7
ashleymills 11:dfd1e0afcb7b 93 #define MMA8452_DATA_RATE_MASK_SHIFT 0x03
ashleymills 11:dfd1e0afcb7b 94
ashleymills 12:172540ff6b8b 95 // mask and shift for general reading and writing
ashleymills 11:dfd1e0afcb7b 96 #define MMA8452_WRITE_MASK 0xFE
ashleymills 11:dfd1e0afcb7b 97 #define MMA8452_READ_MASK 0x01
ashleymills 11:dfd1e0afcb7b 98
ashleymills 12:172540ff6b8b 99 // mask and shift for bit depth reading and writing
ashleymills 11:dfd1e0afcb7b 100 #define MMA8452_BIT_DEPTH_MASK 0xFD
ashleymills 11:dfd1e0afcb7b 101 #define MMA8452_BIT_DEPTH_MASK_SHIFT 0x01
ashleymills 12:172540ff6b8b 102
ashleymills 12:172540ff6b8b 103 // status masks and shifts
ashleymills 12:172540ff6b8b 104 #define MMA8452_STATUS_ZYXDR_MASK 0x08
ashleymills 16:d6dde2318edc 105 #define MMA8452_STATUS_ZDR_MASK 0x04
ashleymills 16:d6dde2318edc 106 #define MMA8452_STATUS_YDR_MASK 0x02
ashleymills 16:d6dde2318edc 107 #define MMA8452_STATUS_XDR_MASK 0x01
ashleymills 11:dfd1e0afcb7b 108
ashleymills 10:ca9ba7ad4e94 109 class MMA8452
nherriot 0:bcf2aa85d7f9 110 {
nherriot 0:bcf2aa85d7f9 111 public:
ashleymills 10:ca9ba7ad4e94 112
ashleymills 11:dfd1e0afcb7b 113 enum DynamicRange {
ashleymills 11:dfd1e0afcb7b 114 DYNAMIC_RANGE_2G=0x00,
ashleymills 11:dfd1e0afcb7b 115 DYNAMIC_RANGE_4G,
ashleymills 11:dfd1e0afcb7b 116 DYNAMIC_RANGE_8G,
ashleymills 11:dfd1e0afcb7b 117 DYNAMIC_RANGE_UNKNOWN
ashleymills 10:ca9ba7ad4e94 118 };
nherriot 0:bcf2aa85d7f9 119
ashleymills 10:ca9ba7ad4e94 120 enum BitDepth {
ashleymills 11:dfd1e0afcb7b 121 BIT_DEPTH_12=0x00,
ashleymills 12:172540ff6b8b 122 BIT_DEPTH_8, // 1 sets fast read mode, hence the inversion
ashleymills 12:172540ff6b8b 123 BIT_DEPTH_UNKNOWN
ashleymills 10:ca9ba7ad4e94 124 };
ashleymills 11:dfd1e0afcb7b 125
ashleymills 11:dfd1e0afcb7b 126 enum DataRateHz {
ashleymills 11:dfd1e0afcb7b 127 RATE_800=0x00,
ashleymills 11:dfd1e0afcb7b 128 RATE_400,
ashleymills 11:dfd1e0afcb7b 129 RATE_200,
ashleymills 11:dfd1e0afcb7b 130 RATE_100,
ashleymills 11:dfd1e0afcb7b 131 RATE_50,
ashleymills 11:dfd1e0afcb7b 132 RATE_12_5,
ashleymills 11:dfd1e0afcb7b 133 RATE_6_25,
ashleymills 11:dfd1e0afcb7b 134 RATE_1_563,
ashleymills 11:dfd1e0afcb7b 135 RATE_UNKNOWN
ashleymills 11:dfd1e0afcb7b 136 };
ashleymills 11:dfd1e0afcb7b 137
nherriot 0:bcf2aa85d7f9 138
ashleymills 15:7620a11149b8 139 /**
ashleymills 15:7620a11149b8 140 * Create an accelerometer object connected to the specified I2C pins.
nherriot 0:bcf2aa85d7f9 141 *
nherriot 0:bcf2aa85d7f9 142 * @param sda I2C data port
ashleymills 15:7620a11149b8 143 * @param scl I2C clock port
ashleymills 15:7620a11149b8 144 * @param frequency
nherriot 0:bcf2aa85d7f9 145 *
nherriot 0:bcf2aa85d7f9 146 */
ashleymills 10:ca9ba7ad4e94 147 MMA8452(PinName sda, PinName scl, int frequency);
nherriot 0:bcf2aa85d7f9 148
ashleymills 15:7620a11149b8 149 /// Destructor
ashleymills 10:ca9ba7ad4e94 150 ~MMA8452();
nherriot 3:ffb0b1650ca2 151
ashleymills 15:7620a11149b8 152 /**
ashleymills 15:7620a11149b8 153 * Puts the MMA8452 in active mode.
ashleymills 15:7620a11149b8 154 * @return 0 on success, 1 on failure.
ashleymills 15:7620a11149b8 155 */
nherriot 0:bcf2aa85d7f9 156 int activate();
nherriot 3:ffb0b1650ca2 157
ashleymills 15:7620a11149b8 158 /**
ashleymills 15:7620a11149b8 159 * Puts the MMA8452 in standby.
ashleymills 15:7620a11149b8 160 * @return 0 on success, 1 on failure.
ashleymills 15:7620a11149b8 161 */
ashleymills 15:7620a11149b8 162 int standby();
nherriot 0:bcf2aa85d7f9 163
nherriot 0:bcf2aa85d7f9 164 /** Initialization of device MMA8452 (required)
nherriot 0:bcf2aa85d7f9 165 */
nherriot 0:bcf2aa85d7f9 166 void init();
nherriot 0:bcf2aa85d7f9 167
ashleymills 15:7620a11149b8 168 /**
ashleymills 15:7620a11149b8 169 * Read the device ID from the accelerometer (should be 0x2a)
nherriot 1:ef026bf28798 170 *
ashleymills 15:7620a11149b8 171 * @param pointer to store the ID
ashleymills 15:7620a11149b8 172 * @return 0 on success, 1 on failure.
nherriot 1:ef026bf28798 173 */
ashleymills 11:dfd1e0afcb7b 174 int getDeviceID(char* dst);
nherriot 0:bcf2aa85d7f9 175
ashleymills 12:172540ff6b8b 176 int getStatus(char* dst);
nherriot 1:ef026bf28798 177
ashleymills 12:172540ff6b8b 178 /**
ashleymills 12:172540ff6b8b 179 * Read the x,y, and z registers of the MMA8452.
nherriot 1:ef026bf28798 180 *
ashleymills 12:172540ff6b8b 181 * @param dst The destination buffer. Note that this needs to be 3 bytes for
ashleymills 12:172540ff6b8b 182 * BIT_DEPTH_8 and 6 bytes for BIT_DEPTH_12. It is upto the caller to ensure this.
ashleymills 12:172540ff6b8b 183 * @return 0 for success, and 1 for failure
nherriot 1:ef026bf28798 184 */
ashleymills 15:7620a11149b8 185 int readXYZRaw(char *dst);
ashleymills 15:7620a11149b8 186
ashleymills 15:7620a11149b8 187 /**
ashleymills 15:7620a11149b8 188 * Read the x,y, and z counts of the MMA7452.
ashleymills 15:7620a11149b8 189 */
ashleymills 13:4bd8b4cd479d 190 int readXYZCounts(int *x, int *y, int *z);
ashleymills 13:4bd8b4cd479d 191 int readXYZGravity(double *x, double *y, double *z);
ashleymills 12:172540ff6b8b 192
ashleymills 13:4bd8b4cd479d 193 int isXReady();
ashleymills 13:4bd8b4cd479d 194 int isYReady();
ashleymills 13:4bd8b4cd479d 195 int isZReady();
ashleymills 12:172540ff6b8b 196 int isXYZReady();
nherriot 0:bcf2aa85d7f9 197
ashleymills 15:7620a11149b8 198 /**
ashleymills 15:7620a11149b8 199 * Read from specified MMA8452 register.
ashleymills 12:172540ff6b8b 200 *
ashleymills 12:172540ff6b8b 201 * @param addr The internal registeraddress of the MMA8452
ashleymills 12:172540ff6b8b 202 * @return The value of the register
ashleymills 12:172540ff6b8b 203 */
ashleymills 11:dfd1e0afcb7b 204 int readRegister(char addr, char *dst);
ashleymills 11:dfd1e0afcb7b 205
ashleymills 11:dfd1e0afcb7b 206 int readRegister(char addr, char *dst, int nbytes);
nherriot 0:bcf2aa85d7f9 207
ashleymills 12:172540ff6b8b 208 /**
ashleymills 12:172540ff6b8b 209 * Write to the specified MMA8452 register.
nherriot 0:bcf2aa85d7f9 210 *
ashleymills 12:172540ff6b8b 211 * @param addr The internal register address
ashleymills 12:172540ff6b8b 212 * @param data Data to write
nherriot 0:bcf2aa85d7f9 213 */
ashleymills 11:dfd1e0afcb7b 214 int writeRegister(char addr, char data);
ashleymills 12:172540ff6b8b 215
ashleymills 12:172540ff6b8b 216 /**
ashleymills 12:172540ff6b8b 217 * Write a data buffer to the specified MMA8452 register.
ashleymills 12:172540ff6b8b 218 *
ashleymills 12:172540ff6b8b 219 * @param addr The internal register address
ashleymills 12:172540ff6b8b 220 * @param data Data buffer to write
ashleymills 12:172540ff6b8b 221 * @param nbytes The length of the data buffer to write
ashleymills 12:172540ff6b8b 222 */
ashleymills 11:dfd1e0afcb7b 223 int writeRegister(char addr, char *data, int nbytes);
ashleymills 11:dfd1e0afcb7b 224
ashleymills 11:dfd1e0afcb7b 225 int logicalANDRegister(char addr, char mask);
ashleymills 11:dfd1e0afcb7b 226 int logicalORRegister(char addr, char mask);
ashleymills 11:dfd1e0afcb7b 227 int logicalXORRegister(char addr, char mask);
nherriot 0:bcf2aa85d7f9 228
ashleymills 11:dfd1e0afcb7b 229 int setDynamicRange(DynamicRange range, int toggleActivation=1);
ashleymills 11:dfd1e0afcb7b 230 int setBitDepth(BitDepth depth, int toggleActivation=1);
ashleymills 11:dfd1e0afcb7b 231 int setDataRate(DataRateHz dataRate, int toggleActivation=1);
ashleymills 15:7620a11149b8 232
ashleymills 11:dfd1e0afcb7b 233 DynamicRange getDynamicRange();
ashleymills 11:dfd1e0afcb7b 234 DataRateHz getDataRate();
ashleymills 12:172540ff6b8b 235 BitDepth getBitDepth();
ashleymills 11:dfd1e0afcb7b 236
ashleymills 17:6e4232c421c0 237 #ifdef MMA8452_DEBUG
ashleymills 11:dfd1e0afcb7b 238 void debugRegister(char reg);
ashleymills 17:6e4232c421c0 239 #endif
nherriot 0:bcf2aa85d7f9 240
nherriot 0:bcf2aa85d7f9 241 private:
ashleymills 10:ca9ba7ad4e94 242 int readRaw(char src, char *dst, int len);
ashleymills 11:dfd1e0afcb7b 243 int maskAndApplyRegister(char reg, char mask, char value, int toggleActivation);
ashleymills 13:4bd8b4cd479d 244
ashleymills 13:4bd8b4cd479d 245 int twelveBitToSigned(char *buf);
ashleymills 13:4bd8b4cd479d 246 int eightBitToSigned(char *buf);
ashleymills 13:4bd8b4cd479d 247 double convertCountToGravity(int count, int countsPerG);
ashleymills 16:d6dde2318edc 248 char getMaskedRegister(int reg, char mask);
ashleymills 8:89272163f395 249
ashleymills 11:dfd1e0afcb7b 250 I2C _i2c;
ashleymills 11:dfd1e0afcb7b 251 int _frequency;
ashleymills 6:f6bde04bf8be 252 int _readAddress;
ashleymills 6:f6bde04bf8be 253 int _writeAddress;
ashleymills 12:172540ff6b8b 254
ashleymills 12:172540ff6b8b 255 BitDepth _bitDepth;
ashleymills 13:4bd8b4cd479d 256 DynamicRange _dynamicRange;
nherriot 0:bcf2aa85d7f9 257
ashleymills 15:7620a11149b8 258 };