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.cpp@11:dfd1e0afcb7b, 2014-03-04 (annotated)
- Committer:
- ashleymills
- Date:
- Tue Mar 04 16:23:40 2014 +0000
- Revision:
- 11:dfd1e0afcb7b
- Parent:
- 10:ca9ba7ad4e94
- Child:
- 12:172540ff6b8b
Started a major rewrite of this library.
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
ashleymills | 11:dfd1e0afcb7b | 1 | // Author: Nicholas Herriot, Ashley Mills |
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 | |
ashleymills | 11:dfd1e0afcb7b | 20 | #include "MMA8452.h" |
ashleymills | 11:dfd1e0afcb7b | 21 | #include "mbed.h" |
ashleymills | 11:dfd1e0afcb7b | 22 | |
ashleymills | 11:dfd1e0afcb7b | 23 | extern Serial pc; |
nherriot | 0:bcf2aa85d7f9 | 24 | |
nherriot | 0:bcf2aa85d7f9 | 25 | // Connect module at I2C address using I2C port pins sda and scl |
ashleymills | 11:dfd1e0afcb7b | 26 | MMA8452::MMA8452(PinName sda, PinName scl, int frequency) : _i2c(sda, scl) , _frequency(frequency) { |
ashleymills | 11:dfd1e0afcb7b | 27 | DBG("Creating MMA8452"); |
ashleymills | 11:dfd1e0afcb7b | 28 | _i2c.frequency(_frequency); |
ashleymills | 11:dfd1e0afcb7b | 29 | |
ashleymills | 11:dfd1e0afcb7b | 30 | // setup read and write addresses to avoid duplication |
ashleymills | 11:dfd1e0afcb7b | 31 | _readAddress = MMA8452_ADDRESS | 0x01; |
ashleymills | 11:dfd1e0afcb7b | 32 | _writeAddress = MMA8452_ADDRESS & 0xFE; |
ashleymills | 11:dfd1e0afcb7b | 33 | DBG("Done"); |
nherriot | 0:bcf2aa85d7f9 | 34 | } |
nherriot | 0:bcf2aa85d7f9 | 35 | |
nherriot | 0:bcf2aa85d7f9 | 36 | |
nherriot | 0:bcf2aa85d7f9 | 37 | // Destroys instance |
ashleymills | 10:ca9ba7ad4e94 | 38 | MMA8452::~MMA8452() {} |
nherriot | 0:bcf2aa85d7f9 | 39 | |
nherriot | 0:bcf2aa85d7f9 | 40 | // Setting the control register bit 1 to true to activate the MMA8452 |
ashleymills | 10:ca9ba7ad4e94 | 41 | int MMA8452::activate() { |
ashleymills | 6:f6bde04bf8be | 42 | // perform write and return error code |
ashleymills | 11:dfd1e0afcb7b | 43 | return logicalORRegister(CTRL_REG_1,MMA8452_ACTIVE_MASK); |
nherriot | 3:ffb0b1650ca2 | 44 | } |
nherriot | 3:ffb0b1650ca2 | 45 | |
ashleymills | 11:dfd1e0afcb7b | 46 | // Setting the control register bit 1 to 0 to standby the MMA8452 |
ashleymills | 11:dfd1e0afcb7b | 47 | int MMA8452::standby() { |
ashleymills | 11:dfd1e0afcb7b | 48 | // perform write and return error code |
ashleymills | 11:dfd1e0afcb7b | 49 | return logicalANDRegister(CTRL_REG_1,MMA8452_STANDBY_MASK); |
nherriot | 5:b3d0abd97e55 | 50 | } |
nherriot | 5:b3d0abd97e55 | 51 | |
ashleymills | 11:dfd1e0afcb7b | 52 | // this reads a register, applies a bitmask with logical AND, sets a value with logical OR, |
ashleymills | 11:dfd1e0afcb7b | 53 | // and optionally goes into and out of standby at the beginning and end of the function respectively |
ashleymills | 11:dfd1e0afcb7b | 54 | int MMA8452::maskAndApplyRegister(char reg, char mask, char value, int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 55 | if(toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 56 | if(standby()) { |
ashleymills | 11:dfd1e0afcb7b | 57 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 58 | } |
ashleymills | 11:dfd1e0afcb7b | 59 | } |
ashleymills | 11:dfd1e0afcb7b | 60 | |
ashleymills | 11:dfd1e0afcb7b | 61 | // read from register |
ashleymills | 11:dfd1e0afcb7b | 62 | char oldValue = 0; |
ashleymills | 11:dfd1e0afcb7b | 63 | if(readRegister(reg,&oldValue)) { |
ashleymills | 11:dfd1e0afcb7b | 64 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 65 | } |
ashleymills | 11:dfd1e0afcb7b | 66 | |
ashleymills | 11:dfd1e0afcb7b | 67 | // apply bitmask |
ashleymills | 11:dfd1e0afcb7b | 68 | oldValue &= mask; |
ashleymills | 11:dfd1e0afcb7b | 69 | |
ashleymills | 11:dfd1e0afcb7b | 70 | // set value |
ashleymills | 11:dfd1e0afcb7b | 71 | oldValue |= value; |
ashleymills | 11:dfd1e0afcb7b | 72 | |
ashleymills | 11:dfd1e0afcb7b | 73 | // write back to register |
ashleymills | 11:dfd1e0afcb7b | 74 | if(writeRegister(reg,oldValue)) { |
ashleymills | 11:dfd1e0afcb7b | 75 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 76 | } |
ashleymills | 11:dfd1e0afcb7b | 77 | |
ashleymills | 11:dfd1e0afcb7b | 78 | if(toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 79 | if(activate()) { |
ashleymills | 11:dfd1e0afcb7b | 80 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 81 | } |
ashleymills | 11:dfd1e0afcb7b | 82 | } |
ashleymills | 11:dfd1e0afcb7b | 83 | return 0; |
nherriot | 0:bcf2aa85d7f9 | 84 | } |
nherriot | 0:bcf2aa85d7f9 | 85 | |
ashleymills | 11:dfd1e0afcb7b | 86 | int MMA8452::setDynamicRange(DynamicRange range, int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 87 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 88 | MMA8452_XYZ_DATA_CFG, |
ashleymills | 11:dfd1e0afcb7b | 89 | MMA8452_DYNAMIC_RANGE_MASK, |
ashleymills | 11:dfd1e0afcb7b | 90 | range, |
ashleymills | 11:dfd1e0afcb7b | 91 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 92 | ); |
nherriot | 0:bcf2aa85d7f9 | 93 | } |
nherriot | 0:bcf2aa85d7f9 | 94 | |
ashleymills | 11:dfd1e0afcb7b | 95 | int MMA8452::setDataRate(DataRateHz dataRate, int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 96 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 97 | MMA8452_CTRL_REG_1, |
ashleymills | 11:dfd1e0afcb7b | 98 | MMA8452_DATA_RATE_MASK, |
ashleymills | 11:dfd1e0afcb7b | 99 | dataRate<<MMA8452_DATA_RATE_MASK_SHIFT, |
ashleymills | 11:dfd1e0afcb7b | 100 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 101 | ); |
nherriot | 3:ffb0b1650ca2 | 102 | } |
nherriot | 3:ffb0b1650ca2 | 103 | |
ashleymills | 11:dfd1e0afcb7b | 104 | int MMA8452::setBitDepth(BitDepth depth,int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 105 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 106 | MMA8452_CTRL_REG_1, |
ashleymills | 11:dfd1e0afcb7b | 107 | MMA8452_BIT_DEPTH_MASK, |
ashleymills | 11:dfd1e0afcb7b | 108 | depth<<MMA8452_BIT_DEPTH_MASK_SHIFT, |
ashleymills | 11:dfd1e0afcb7b | 109 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 110 | ); |
nherriot | 3:ffb0b1650ca2 | 111 | } |
nherriot | 3:ffb0b1650ca2 | 112 | |
nherriot | 0:bcf2aa85d7f9 | 113 | |
nherriot | 1:ef026bf28798 | 114 | // Get device ID |
ashleymills | 11:dfd1e0afcb7b | 115 | int MMA8452::getDeviceID(char *dst) |
nherriot | 1:ef026bf28798 | 116 | { |
ashleymills | 10:ca9ba7ad4e94 | 117 | return readRegister(WHO_AM_I,dst); |
nherriot | 1:ef026bf28798 | 118 | } |
nherriot | 1:ef026bf28798 | 119 | |
nherriot | 1:ef026bf28798 | 120 | |
ashleymills | 10:ca9ba7ad4e94 | 121 | int MMA8452::readRaw(char src, char *dst, int len) { |
ashleymills | 8:89272163f395 | 122 | // this is the register we want to get data from |
ashleymills | 8:89272163f395 | 123 | char register_address[1]; |
ashleymills | 8:89272163f395 | 124 | register_address[0] = src; |
ashleymills | 8:89272163f395 | 125 | |
ashleymills | 11:dfd1e0afcb7b | 126 | if(_i2c.write(_writeAddress,register_address,1,true) == 0) |
ashleymills | 8:89272163f395 | 127 | { |
ashleymills | 11:dfd1e0afcb7b | 128 | if(_i2c.read(_readAddress,dst,len)==0) |
ashleymills | 8:89272163f395 | 129 | { |
ashleymills | 8:89272163f395 | 130 | return 0; |
ashleymills | 8:89272163f395 | 131 | } |
ashleymills | 8:89272163f395 | 132 | } |
ashleymills | 8:89272163f395 | 133 | |
ashleymills | 8:89272163f395 | 134 | // failure case, zero array and return error |
ashleymills | 8:89272163f395 | 135 | for(int i=0; i<len; i++) { |
ashleymills | 8:89272163f395 | 136 | dst[i] = 0x00; |
ashleymills | 8:89272163f395 | 137 | } |
ashleymills | 8:89272163f395 | 138 | return 1; |
ashleymills | 8:89272163f395 | 139 | } |
nherriot | 3:ffb0b1650ca2 | 140 | |
nherriot | 3:ffb0b1650ca2 | 141 | // Reads x data. This method reads two registers containing the x-axis values from the accelerometer. |
nherriot | 3:ffb0b1650ca2 | 142 | // It takes a 2 byte char array and copies the register values into the buffer. If it fails the char array |
nherriot | 3:ffb0b1650ca2 | 143 | // is set to '0'. It returns '0' success '1' fail. This method does nothing to the registers - just returns |
nherriot | 3:ffb0b1650ca2 | 144 | // the raw data. |
ashleymills | 10:ca9ba7ad4e94 | 145 | //int MMA8452::read_x(int& xaxisLSB) |
ashleymills | 11:dfd1e0afcb7b | 146 | int MMA8452::readRawX(char *xaxis) { |
ashleymills | 10:ca9ba7ad4e94 | 147 | return readRaw(OUT_X_MSB,xaxis,2); |
nherriot | 0:bcf2aa85d7f9 | 148 | } |
nherriot | 0:bcf2aa85d7f9 | 149 | |
nherriot | 0:bcf2aa85d7f9 | 150 | |
nherriot | 3:ffb0b1650ca2 | 151 | // Reads y data. This method reads two registers containing the x-axis values from the accelerometer. |
nherriot | 3:ffb0b1650ca2 | 152 | // It takes a 2 byte char array and copies the register values into the buffer. If it fails the char array |
nherriot | 3:ffb0b1650ca2 | 153 | // is set to '0'. It returns '0' success '1' fail. This method does nothing to the registers - just returns |
nherriot | 3:ffb0b1650ca2 | 154 | // the raw data. |
nherriot | 3:ffb0b1650ca2 | 155 | |
ashleymills | 10:ca9ba7ad4e94 | 156 | int MMA8452::readRawY(char *yaxis) { |
ashleymills | 10:ca9ba7ad4e94 | 157 | return readRaw(OUT_Y_MSB,yaxis,2); |
nherriot | 3:ffb0b1650ca2 | 158 | } |
nherriot | 3:ffb0b1650ca2 | 159 | |
nherriot | 0:bcf2aa85d7f9 | 160 | |
nherriot | 3:ffb0b1650ca2 | 161 | |
nherriot | 3:ffb0b1650ca2 | 162 | // Reads z data. This method reads two registers containing the x-axis values from the accelerometer. |
nherriot | 3:ffb0b1650ca2 | 163 | // It takes a 2 byte char array and copies the register values into the buffer. If it fails the char array |
nherriot | 3:ffb0b1650ca2 | 164 | // is set to '0'. It returns '0' success '1' fail. This method does nothing to the registers - just returns |
nherriot | 3:ffb0b1650ca2 | 165 | // the raw data. |
nherriot | 3:ffb0b1650ca2 | 166 | |
ashleymills | 10:ca9ba7ad4e94 | 167 | int MMA8452::readRawZ(char *zaxis) |
nherriot | 3:ffb0b1650ca2 | 168 | { |
ashleymills | 10:ca9ba7ad4e94 | 169 | return readRaw(OUT_Z_MSB,zaxis,2); |
nherriot | 3:ffb0b1650ca2 | 170 | } |
nherriot | 0:bcf2aa85d7f9 | 171 | |
nherriot | 0:bcf2aa85d7f9 | 172 | |
nherriot | 0:bcf2aa85d7f9 | 173 | |
nherriot | 0:bcf2aa85d7f9 | 174 | // Reads y data |
ashleymills | 10:ca9ba7ad4e94 | 175 | int MMA8452::read_y() |
nherriot | 0:bcf2aa85d7f9 | 176 | { |
nherriot | 1:ef026bf28798 | 177 | char mcu_address = (MMA8452_ADDRESS <<1); |
nherriot | 0:bcf2aa85d7f9 | 178 | |
ashleymills | 11:dfd1e0afcb7b | 179 | _i2c.start(); // Start |
ashleymills | 11:dfd1e0afcb7b | 180 | _i2c.write(mcu_address); // A write to device 0x98 |
ashleymills | 11:dfd1e0afcb7b | 181 | _i2c.write(OUT_Y_MSB); // Register to read |
ashleymills | 11:dfd1e0afcb7b | 182 | _i2c.start(); |
ashleymills | 11:dfd1e0afcb7b | 183 | _i2c.write(mcu_address); // Read from device 0x99 |
ashleymills | 11:dfd1e0afcb7b | 184 | int y = _i2c.read(0); // Read the data |
ashleymills | 11:dfd1e0afcb7b | 185 | _i2c.stop(); |
nherriot | 0:bcf2aa85d7f9 | 186 | |
nherriot | 1:ef026bf28798 | 187 | return y; |
nherriot | 0:bcf2aa85d7f9 | 188 | |
nherriot | 0:bcf2aa85d7f9 | 189 | } |
nherriot | 0:bcf2aa85d7f9 | 190 | |
nherriot | 0:bcf2aa85d7f9 | 191 | // Reads z data |
ashleymills | 10:ca9ba7ad4e94 | 192 | int MMA8452::read_z() |
nherriot | 0:bcf2aa85d7f9 | 193 | { |
nherriot | 1:ef026bf28798 | 194 | char mcu_address = (MMA8452_ADDRESS <<1); |
nherriot | 0:bcf2aa85d7f9 | 195 | |
ashleymills | 11:dfd1e0afcb7b | 196 | _i2c.start(); // Start |
ashleymills | 11:dfd1e0afcb7b | 197 | _i2c.write(mcu_address); // A write to device 0x98 |
ashleymills | 11:dfd1e0afcb7b | 198 | _i2c.write(OUT_Z_MSB); // Register to read |
ashleymills | 11:dfd1e0afcb7b | 199 | _i2c.start(); |
ashleymills | 11:dfd1e0afcb7b | 200 | _i2c.write(mcu_address); // Read from device 0x99 |
ashleymills | 11:dfd1e0afcb7b | 201 | int z = _i2c.read(0); // Read the data |
ashleymills | 11:dfd1e0afcb7b | 202 | _i2c.stop(); |
nherriot | 0:bcf2aa85d7f9 | 203 | |
nherriot | 1:ef026bf28798 | 204 | return z; |
nherriot | 0:bcf2aa85d7f9 | 205 | |
nherriot | 0:bcf2aa85d7f9 | 206 | } |
nherriot | 0:bcf2aa85d7f9 | 207 | |
nherriot | 0:bcf2aa85d7f9 | 208 | |
ashleymills | 11:dfd1e0afcb7b | 209 | MMA8452::DynamicRange MMA8452::getDynamicRange() { |
ashleymills | 11:dfd1e0afcb7b | 210 | char rval = 0; |
ashleymills | 11:dfd1e0afcb7b | 211 | if(readRegister(MMA8452_CTRL_REG_1,&rval)) { |
ashleymills | 11:dfd1e0afcb7b | 212 | return MMA8452::DYNAMIC_RANGE_UNKNOWN; |
ashleymills | 11:dfd1e0afcb7b | 213 | } |
ashleymills | 11:dfd1e0afcb7b | 214 | rval &= (MMA8452_DYNAMIC_RANGE_MASK^0xFF); |
ashleymills | 11:dfd1e0afcb7b | 215 | return (MMA8452::DynamicRange)rval; |
ashleymills | 11:dfd1e0afcb7b | 216 | } |
ashleymills | 11:dfd1e0afcb7b | 217 | |
ashleymills | 11:dfd1e0afcb7b | 218 | MMA8452::DataRateHz MMA8452::getDataRate() { |
ashleymills | 11:dfd1e0afcb7b | 219 | char rval = 0; |
ashleymills | 11:dfd1e0afcb7b | 220 | if(readRegister(MMA8452_CTRL_REG_1,&rval)) { |
ashleymills | 11:dfd1e0afcb7b | 221 | return MMA8452::RATE_UNKNOWN; |
ashleymills | 11:dfd1e0afcb7b | 222 | } |
ashleymills | 11:dfd1e0afcb7b | 223 | // logical AND with inverse of mask |
ashleymills | 11:dfd1e0afcb7b | 224 | rval = rval&(MMA8452_DATA_RATE_MASK^0xFF); |
ashleymills | 11:dfd1e0afcb7b | 225 | // shift back into position |
ashleymills | 11:dfd1e0afcb7b | 226 | rval >>= MMA8452_DATA_RATE_MASK_SHIFT; |
ashleymills | 11:dfd1e0afcb7b | 227 | return (MMA8452::DataRateHz)rval; |
ashleymills | 11:dfd1e0afcb7b | 228 | } |
ashleymills | 11:dfd1e0afcb7b | 229 | |
nherriot | 0:bcf2aa85d7f9 | 230 | // Reads xyz |
ashleymills | 10:ca9ba7ad4e94 | 231 | int MMA8452::readRawXYZ(char *x, char *y, char *z) |
nherriot | 1:ef026bf28798 | 232 | { |
nherriot | 1:ef026bf28798 | 233 | |
nherriot | 1:ef026bf28798 | 234 | |
nherriot | 1:ef026bf28798 | 235 | char mcu_address = (MMA8452_ADDRESS <<1); |
nherriot | 1:ef026bf28798 | 236 | char register_buffer[6] ={0,0,0,0,0,0}; |
nherriot | 1:ef026bf28798 | 237 | const char Addr_X = OUT_X_MSB; |
ashleymills | 11:dfd1e0afcb7b | 238 | _i2c.write(mcu_address); // A write to device 0x98 |
ashleymills | 11:dfd1e0afcb7b | 239 | _i2c.write(MMA8452_ADDRESS, &Addr_X, 1); // Pointer to the OUT_X_MSB register |
nherriot | 1:ef026bf28798 | 240 | |
ashleymills | 11:dfd1e0afcb7b | 241 | if(_i2c.write(mcu_address,&Addr_X,1) == 0) |
nherriot | 1:ef026bf28798 | 242 | { |
ashleymills | 11:dfd1e0afcb7b | 243 | if(_i2c.read(mcu_address,register_buffer,6) == 0) |
nherriot | 1:ef026bf28798 | 244 | { |
nherriot | 1:ef026bf28798 | 245 | *x = register_buffer[1]; |
nherriot | 1:ef026bf28798 | 246 | *y = register_buffer[3]; |
nherriot | 1:ef026bf28798 | 247 | *z = register_buffer[5]; |
nherriot | 1:ef026bf28798 | 248 | return 0; // yahoooooo |
nherriot | 1:ef026bf28798 | 249 | } |
nherriot | 1:ef026bf28798 | 250 | else |
nherriot | 1:ef026bf28798 | 251 | { |
nherriot | 1:ef026bf28798 | 252 | return 1; // failed oh nooo! |
nherriot | 1:ef026bf28798 | 253 | } |
nherriot | 1:ef026bf28798 | 254 | } |
nherriot | 1:ef026bf28798 | 255 | else |
nherriot | 1:ef026bf28798 | 256 | { |
nherriot | 1:ef026bf28798 | 257 | return 1; // failed oh nooo! |
nherriot | 1:ef026bf28798 | 258 | } |
nherriot | 0:bcf2aa85d7f9 | 259 | |
nherriot | 1:ef026bf28798 | 260 | } |
nherriot | 0:bcf2aa85d7f9 | 261 | |
ashleymills | 11:dfd1e0afcb7b | 262 | // apply an AND mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 263 | int MMA8452::logicalANDRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 264 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 265 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 266 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 267 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 268 | } |
ashleymills | 11:dfd1e0afcb7b | 269 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 270 | value &= mask; |
ashleymills | 11:dfd1e0afcb7b | 271 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 272 | } |
ashleymills | 11:dfd1e0afcb7b | 273 | |
ashleymills | 11:dfd1e0afcb7b | 274 | |
ashleymills | 11:dfd1e0afcb7b | 275 | // apply an OR mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 276 | int MMA8452::logicalORRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 277 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 278 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 279 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 280 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 281 | } |
ashleymills | 11:dfd1e0afcb7b | 282 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 283 | value |= mask; |
ashleymills | 11:dfd1e0afcb7b | 284 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 285 | } |
ashleymills | 11:dfd1e0afcb7b | 286 | |
nherriot | 0:bcf2aa85d7f9 | 287 | |
ashleymills | 11:dfd1e0afcb7b | 288 | // apply an OR mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 289 | int MMA8452::logicalXORRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 290 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 291 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 292 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 293 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 294 | } |
ashleymills | 11:dfd1e0afcb7b | 295 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 296 | value ^= mask; |
ashleymills | 11:dfd1e0afcb7b | 297 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 298 | } |
ashleymills | 11:dfd1e0afcb7b | 299 | |
ashleymills | 11:dfd1e0afcb7b | 300 | // Write register (The device must be placed in Standby Mode to change the value of the registers) |
ashleymills | 11:dfd1e0afcb7b | 301 | int MMA8452::writeRegister(char addr, char data) { |
ashleymills | 11:dfd1e0afcb7b | 302 | // what this actually does is the following |
ashleymills | 11:dfd1e0afcb7b | 303 | // 1. tell I2C bus to start transaction |
ashleymills | 11:dfd1e0afcb7b | 304 | // 2. tell slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 305 | // 3. send the write address |
ashleymills | 11:dfd1e0afcb7b | 306 | // 4. send the data to write |
ashleymills | 11:dfd1e0afcb7b | 307 | // 5. tell I2C bus to end transaction |
ashleymills | 11:dfd1e0afcb7b | 308 | |
ashleymills | 11:dfd1e0afcb7b | 309 | // we can wrap this up in the I2C library write function |
ashleymills | 11:dfd1e0afcb7b | 310 | char buf[2] = {0,0}; |
ashleymills | 11:dfd1e0afcb7b | 311 | buf[0] = addr; |
ashleymills | 11:dfd1e0afcb7b | 312 | buf[1] = data; |
ashleymills | 11:dfd1e0afcb7b | 313 | return _i2c.write(MMA8452_ADDRESS, buf,2); |
ashleymills | 11:dfd1e0afcb7b | 314 | // note, could also do return writeRegister(addr,&data,1); |
nherriot | 0:bcf2aa85d7f9 | 315 | } |
nherriot | 0:bcf2aa85d7f9 | 316 | |
ashleymills | 11:dfd1e0afcb7b | 317 | |
ashleymills | 11:dfd1e0afcb7b | 318 | int MMA8452::writeRegister(char addr, char *data, int nbytes) { |
ashleymills | 11:dfd1e0afcb7b | 319 | // writing multiple bytes is a little bit annoying because |
ashleymills | 11:dfd1e0afcb7b | 320 | // the I2C library doesn't support sending the address separately |
ashleymills | 11:dfd1e0afcb7b | 321 | // so we just do it manually |
nherriot | 0:bcf2aa85d7f9 | 322 | |
ashleymills | 11:dfd1e0afcb7b | 323 | // 1. tell I2C bus to start transaction |
ashleymills | 11:dfd1e0afcb7b | 324 | _i2c.start(); |
ashleymills | 11:dfd1e0afcb7b | 325 | // 2. tell slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 326 | if(_i2c.write(_writeAddress)!=1) { |
ashleymills | 11:dfd1e0afcb7b | 327 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 328 | } |
ashleymills | 11:dfd1e0afcb7b | 329 | // 3. send the write address |
ashleymills | 11:dfd1e0afcb7b | 330 | if(_i2c.write(addr)!=1) { |
ashleymills | 11:dfd1e0afcb7b | 331 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 332 | } |
ashleymills | 11:dfd1e0afcb7b | 333 | // 4. send the data to write |
ashleymills | 11:dfd1e0afcb7b | 334 | for(int i=0; i<nbytes; i++) { |
ashleymills | 11:dfd1e0afcb7b | 335 | if(_i2c.write(data[i])!=1) { |
ashleymills | 11:dfd1e0afcb7b | 336 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 337 | } |
ashleymills | 11:dfd1e0afcb7b | 338 | } |
ashleymills | 11:dfd1e0afcb7b | 339 | // 5. tell I2C bus to end transaction |
ashleymills | 11:dfd1e0afcb7b | 340 | _i2c.stop(); |
ashleymills | 11:dfd1e0afcb7b | 341 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 342 | } |
ashleymills | 11:dfd1e0afcb7b | 343 | |
ashleymills | 11:dfd1e0afcb7b | 344 | int MMA8452::readRegister(char addr, char *dst, int nbytes) { |
ashleymills | 11:dfd1e0afcb7b | 345 | // this is a bit odd, but basically proceeds like this |
ashleymills | 11:dfd1e0afcb7b | 346 | // 1. Send a start command |
ashleymills | 11:dfd1e0afcb7b | 347 | // 2. Tell the slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 348 | // 3. Send the address of the register (addr) |
ashleymills | 11:dfd1e0afcb7b | 349 | // 4. Send another start command to delineate read portion |
ashleymills | 11:dfd1e0afcb7b | 350 | // 5. Tell the slave we want to read (slave address & read flag) |
ashleymills | 11:dfd1e0afcb7b | 351 | // 6. Read the register value bytes |
ashleymills | 11:dfd1e0afcb7b | 352 | // 7. Send a stop command |
ashleymills | 11:dfd1e0afcb7b | 353 | |
ashleymills | 11:dfd1e0afcb7b | 354 | // we can wrap this process in the I2C library read and write commands |
ashleymills | 11:dfd1e0afcb7b | 355 | if(_i2c.write(MMA8452_ADDRESS,&addr,1,true)) { |
ashleymills | 11:dfd1e0afcb7b | 356 | return 1; |
ashleymills | 8:89272163f395 | 357 | } |
ashleymills | 11:dfd1e0afcb7b | 358 | return _i2c.read(MMA8452_ADDRESS,dst,nbytes); |
ashleymills | 11:dfd1e0afcb7b | 359 | } |
ashleymills | 11:dfd1e0afcb7b | 360 | |
ashleymills | 11:dfd1e0afcb7b | 361 | // most registers are 1 byte, so here is a convenience function |
ashleymills | 11:dfd1e0afcb7b | 362 | int MMA8452::readRegister(char addr, char *dst) { |
ashleymills | 11:dfd1e0afcb7b | 363 | return readRegister(addr,dst,1); |
nherriot | 0:bcf2aa85d7f9 | 364 | } |
ashleymills | 11:dfd1e0afcb7b | 365 | |
ashleymills | 11:dfd1e0afcb7b | 366 | void MMA8452::debugRegister(char reg) { |
ashleymills | 11:dfd1e0afcb7b | 367 | // get register value |
ashleymills | 11:dfd1e0afcb7b | 368 | char v = 0; |
ashleymills | 11:dfd1e0afcb7b | 369 | if(readRegister(reg,&v)) { |
ashleymills | 11:dfd1e0afcb7b | 370 | DBG("Error reading control register"); |
ashleymills | 11:dfd1e0afcb7b | 371 | return; |
ashleymills | 11:dfd1e0afcb7b | 372 | } |
ashleymills | 11:dfd1e0afcb7b | 373 | // print out details |
ashleymills | 11:dfd1e0afcb7b | 374 | switch(reg) { |
ashleymills | 11:dfd1e0afcb7b | 375 | case MMA8452_CTRL_REG_1: |
ashleymills | 11:dfd1e0afcb7b | 376 | DBG("CTRL_REG_1 has value: 0x%x",v); |
ashleymills | 11:dfd1e0afcb7b | 377 | DBG(" 7 ALSP_RATE_1: %d",(v&0x80)>>7); |
ashleymills | 11:dfd1e0afcb7b | 378 | DBG(" 6 ALSP_RATE_0: %d",(v&0x40)>>6); |
ashleymills | 11:dfd1e0afcb7b | 379 | DBG(" 5 DR2: %d", (v&0x20)>>5); |
ashleymills | 11:dfd1e0afcb7b | 380 | DBG(" 4 DR1: %d", (v&0x10)>>4); |
ashleymills | 11:dfd1e0afcb7b | 381 | DBG(" 3 DR0: %d", (v&0x08)>>3); |
ashleymills | 11:dfd1e0afcb7b | 382 | DBG(" 2 LNOISE: %d", (v&0x04)>>2); |
ashleymills | 11:dfd1e0afcb7b | 383 | DBG(" 1 FREAD: %d", (v&0x02)>>1); |
ashleymills | 11:dfd1e0afcb7b | 384 | DBG(" 0 ACTIVE: %d", (v&0x01)); |
ashleymills | 11:dfd1e0afcb7b | 385 | break; |
ashleymills | 11:dfd1e0afcb7b | 386 | |
ashleymills | 11:dfd1e0afcb7b | 387 | case MMA8452_XYZ_DATA_CFG: |
ashleymills | 11:dfd1e0afcb7b | 388 | DBG("XYZ_DATA_CFG has value: 0x%x",v); |
ashleymills | 11:dfd1e0afcb7b | 389 | DBG(" 7 Unused: %d", (v&0x80)>>7); |
ashleymills | 11:dfd1e0afcb7b | 390 | DBG(" 6 0: %d", (v&0x40)>>6); |
ashleymills | 11:dfd1e0afcb7b | 391 | DBG(" 5 0: %d", (v&0x20)>>5); |
ashleymills | 11:dfd1e0afcb7b | 392 | DBG(" 4 HPF_Out: %d",(v&0x10)>>4); |
ashleymills | 11:dfd1e0afcb7b | 393 | DBG(" 3 0: %d", (v&0x08)>>3); |
ashleymills | 11:dfd1e0afcb7b | 394 | DBG(" 2 0: %d", (v&0x04)>>2); |
ashleymills | 11:dfd1e0afcb7b | 395 | DBG(" 1 FS1: %d", (v&0x02)>>1); |
ashleymills | 11:dfd1e0afcb7b | 396 | DBG(" 0 FS0: %d", (v&0x01)); |
ashleymills | 11:dfd1e0afcb7b | 397 | switch(v&0x03) { |
ashleymills | 11:dfd1e0afcb7b | 398 | case 0: |
ashleymills | 11:dfd1e0afcb7b | 399 | DBG("Dynamic range: 2G"); |
ashleymills | 11:dfd1e0afcb7b | 400 | break; |
ashleymills | 11:dfd1e0afcb7b | 401 | case 1: |
ashleymills | 11:dfd1e0afcb7b | 402 | DBG("Dynamic range: 4G"); |
ashleymills | 11:dfd1e0afcb7b | 403 | break; |
ashleymills | 11:dfd1e0afcb7b | 404 | case 2: |
ashleymills | 11:dfd1e0afcb7b | 405 | DBG("Dynamic range: 8G"); |
ashleymills | 11:dfd1e0afcb7b | 406 | break; |
ashleymills | 11:dfd1e0afcb7b | 407 | default: |
ashleymills | 11:dfd1e0afcb7b | 408 | DBG("Unknown dynamic range"); |
ashleymills | 11:dfd1e0afcb7b | 409 | break; |
ashleymills | 11:dfd1e0afcb7b | 410 | } |
ashleymills | 11:dfd1e0afcb7b | 411 | break; |
ashleymills | 11:dfd1e0afcb7b | 412 | |
ashleymills | 11:dfd1e0afcb7b | 413 | default: |
ashleymills | 11:dfd1e0afcb7b | 414 | DBG("Unknown register address: 0x%x",reg); |
ashleymills | 11:dfd1e0afcb7b | 415 | break; |
ashleymills | 11:dfd1e0afcb7b | 416 | } |
ashleymills | 11:dfd1e0afcb7b | 417 | } |