Jim Carver / MMA8652

A basic library for the MMA8652 accelerometer, provides data in either floating point G's or as a signed 16 bit integer.

Dependents:   Hello_MMA8652 Multi-Sensor Buddi_Blueband Freescale_Multi-Sensor_Shield ... more

MMA8652.cpp@1:ff30cc4759b4, 2014-04-19 (annotated)

Committer:
JimCarver
Date:
Sat Apr 19 01:28:26 2014 +0000
Revision:
1:ff30cc4759b4
Parent:
0:3ae1e808e61c 
Added features

Who changed what in which revision?

UserRevisionLine numberNew contents of line
JimCarver 1:ff30cc4759b4 1 /* Copyright (c) 2010-2011 mbed.org, MIT License
JimCarver 1:ff30cc4759b4 2 *
JimCarver 1:ff30cc4759b4 3 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
JimCarver 1:ff30cc4759b4 4 * and associated documentation files (the "Software"), to deal in the Software without
JimCarver 1:ff30cc4759b4 5 * restriction, including without limitation the rights to use, copy, modify, merge, publish,
JimCarver 1:ff30cc4759b4 6 * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
JimCarver 1:ff30cc4759b4 7 * Software is furnished to do so, subject to the following conditions:
JimCarver 1:ff30cc4759b4 8 *
JimCarver 1:ff30cc4759b4 9 * The above copyright notice and this permission notice shall be included in all copies or
JimCarver 1:ff30cc4759b4 10 * substantial portions of the Software.
JimCarver 1:ff30cc4759b4 11 *
JimCarver 1:ff30cc4759b4 12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
JimCarver 1:ff30cc4759b4 13 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
JimCarver 1:ff30cc4759b4 14 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
JimCarver 1:ff30cc4759b4 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
JimCarver 1:ff30cc4759b4 16 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
JimCarver 1:ff30cc4759b4 17 */
JimCarver 1:ff30cc4759b4 18
JimCarver 1:ff30cc4759b4 19 #include "MMA8652.h"
JimCarver 1:ff30cc4759b4 20 #define UINT14_MAX 16383
JimCarver 1:ff30cc4759b4 21
JimCarver 0:3ae1e808e61c 22 MMA8652::MMA8652(PinName sda, PinName scl) : _i2c(sda, scl) {
JimCarver 0:3ae1e808e61c 23
JimCarver 0:3ae1e808e61c 24 begin();
JimCarver 0:3ae1e808e61c 25 }
JimCarver 1:ff30cc4759b4 26
JimCarver 1:ff30cc4759b4 27
JimCarver 1:ff30cc4759b4 28 MMA8652::~MMA8652() { }
JimCarver 1:ff30cc4759b4 29
JimCarver 0:3ae1e808e61c 30
JimCarver 0:3ae1e808e61c 31 void MMA8652::RegRead( char reg, char * d, int len)
JimCarver 0:3ae1e808e61c 32 {
JimCarver 0:3ae1e808e61c 33 char cmd[1];
JimCarver 0:3ae1e808e61c 34 cmd[0] = reg;
JimCarver 0:3ae1e808e61c 35 char i2c_addr = MMA8652_SLAVE_ADDR;
JimCarver 1:ff30cc4759b4 36 _i2c.write( i2c_addr, cmd, 1, true);
JimCarver 0:3ae1e808e61c 37 _i2c.read ( i2c_addr, d, len);
JimCarver 0:3ae1e808e61c 38 }
JimCarver 0:3ae1e808e61c 39
JimCarver 0:3ae1e808e61c 40 void MMA8652::begin(void)
JimCarver 0:3ae1e808e61c 41 {
JimCarver 0:3ae1e808e61c 42 char data[2];
JimCarver 0:3ae1e808e61c 43 // write 0000 0000 = 0x00 to accelerometer control register 1 to place MMA8652 into
JimCarver 0:3ae1e808e61c 44 // standby
JimCarver 0:3ae1e808e61c 45 // [7-1] = 0000 000
JimCarver 0:3ae1e808e61c 46 // [0]: active=0
JimCarver 0:3ae1e808e61c 47 data[0] = MMA8652_CTRL_REG1;
JimCarver 0:3ae1e808e61c 48 data[1] = 0x00;
JimCarver 0:3ae1e808e61c 49 _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
JimCarver 0:3ae1e808e61c 50
JimCarver 0:3ae1e808e61c 51 // write 0000 0001= 0x01 to XYZ_DATA_CFG register
JimCarver 0:3ae1e808e61c 52 // [7]: reserved
JimCarver 0:3ae1e808e61c 53 // [6]: reserved
JimCarver 0:3ae1e808e61c 54 // [5]: reserved
JimCarver 0:3ae1e808e61c 55 // [4]: hpf_out=0
JimCarver 0:3ae1e808e61c 56 // [3]: reserved
JimCarver 0:3ae1e808e61c 57 // [2]: reserved
JimCarver 0:3ae1e808e61c 58 // [1-0]: fs=00 for accelerometer range of +/-2g range with 0.244mg/LSB
JimCarver 0:3ae1e808e61c 59 data[0] = MMA8652_XYZ_DATA_CFG;
JimCarver 0:3ae1e808e61c 60 data[1] = 0x00;
JimCarver 0:3ae1e808e61c 61 _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
JimCarver 0:3ae1e808e61c 62
JimCarver 0:3ae1e808e61c 63 // write 0000 1101 = 0x0D to accelerometer control register 1
JimCarver 0:3ae1e808e61c 64 // [7-6]: aslp_rate=00
JimCarver 0:3ae1e808e61c 65 // [5-3]: dr=100 for 50Hz data rate
JimCarver 0:3ae1e808e61c 66 // [2]: 0
JimCarver 0:3ae1e808e61c 67 // [1]: 0
JimCarver 0:3ae1e808e61c 68 // [0]: active=1 to take the part out of standby and enable sampling
JimCarver 0:3ae1e808e61c 69 data[0] = MMA8652_CTRL_REG1;
JimCarver 0:3ae1e808e61c 70 data[1] = 0x21;
JimCarver 0:3ae1e808e61c 71 _i2c.write( MMA8652_SLAVE_ADDR, data, 2);
JimCarver 0:3ae1e808e61c 72 }
JimCarver 0:3ae1e808e61c 73
JimCarver 1:ff30cc4759b4 74 char MMA8652::getWhoAmI(void)
JimCarver 1:ff30cc4759b4 75 {
JimCarver 1:ff30cc4759b4 76 static char d;
JimCarver 1:ff30cc4759b4 77 RegRead( /*MMA8652_WHOAMI*/ 0x0d, &d, 1);
JimCarver 1:ff30cc4759b4 78 return(d);
JimCarver 1:ff30cc4759b4 79 }
JimCarver 1:ff30cc4759b4 80
JimCarver 0:3ae1e808e61c 81 void MMA8652::ReadXYZ(float * a)
JimCarver 0:3ae1e808e61c 82 {
JimCarver 0:3ae1e808e61c 83 char d[7];
JimCarver 0:3ae1e808e61c 84 int16_t t[6];
JimCarver 0:3ae1e808e61c 85
JimCarver 0:3ae1e808e61c 86 RegRead( MMA8652_STATUS, d, 7);
JimCarver 0:3ae1e808e61c 87 t[0] = ((d[1] * 256) + ((unsigned short) d[2]));
JimCarver 0:3ae1e808e61c 88 t[1] = ((d[3] * 256) + ((unsigned short) d[4]));
JimCarver 0:3ae1e808e61c 89 t[2] = ((d[5] * 256) + ((unsigned short) d[6]));
JimCarver 0:3ae1e808e61c 90
JimCarver 0:3ae1e808e61c 91 a[0] = (float) t[0] / 16384.0;
JimCarver 0:3ae1e808e61c 92 a[1] = (float) t[1] / 16384.0;
JimCarver 0:3ae1e808e61c 93 a[2] = (float) t[2] / 16384.0;
JimCarver 0:3ae1e808e61c 94
JimCarver 1:ff30cc4759b4 95 }
JimCarver 1:ff30cc4759b4 96
JimCarver 1:ff30cc4759b4 97
JimCarver 1:ff30cc4759b4 98 void MMA8652::ReadXYZraw(int16_t * d)
JimCarver 1:ff30cc4759b4 99 {
JimCarver 1:ff30cc4759b4 100 char res[6];
JimCarver 1:ff30cc4759b4 101 int16_t acc;
JimCarver 1:ff30cc4759b4 102 RegRead( MMA8652_OUT_X_MSB, res, 6);
JimCarver 1:ff30cc4759b4 103
JimCarver 1:ff30cc4759b4 104 acc = (res[0] << 6) | (res[1] >> 2);
JimCarver 1:ff30cc4759b4 105 if (acc > UINT14_MAX/2)
JimCarver 1:ff30cc4759b4 106 acc -= UINT14_MAX;
JimCarver 1:ff30cc4759b4 107 d[0] = acc;
JimCarver 1:ff30cc4759b4 108 acc = (res[2] << 6) | (res[3] >> 2);
JimCarver 1:ff30cc4759b4 109 if (acc > UINT14_MAX/2)
JimCarver 1:ff30cc4759b4 110 acc -= UINT14_MAX;
JimCarver 1:ff30cc4759b4 111 d[1] = acc;
JimCarver 1:ff30cc4759b4 112 acc = (res[4] << 6) | (res[5] >> 2);
JimCarver 1:ff30cc4759b4 113 if (acc > UINT14_MAX/2)
JimCarver 1:ff30cc4759b4 114 acc -= UINT14_MAX;
JimCarver 1:ff30cc4759b4 115 d[2] = acc;
JimCarver 1:ff30cc4759b4 116 }
JimCarver 1:ff30cc4759b4 117
JimCarver 1:ff30cc4759b4 118