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MMA8452.cpp@13:4bd8b4cd479d, 2014-03-05 (annotated)
- Committer:
- ashleymills
- Date:
- Wed Mar 05 15:04:13 2014 +0000
- Revision:
- 13:4bd8b4cd479d
- Parent:
- 12:172540ff6b8b
- Child:
- 14:0602b45ca70f
Has routines to read raw, counts, and gravity.
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 | 12:172540ff6b8b | 28 | |
ashleymills | 12:172540ff6b8b | 29 | // set I2C frequency |
ashleymills | 11:dfd1e0afcb7b | 30 | _i2c.frequency(_frequency); |
ashleymills | 11:dfd1e0afcb7b | 31 | |
ashleymills | 12:172540ff6b8b | 32 | // setup read and write addresses for convenience |
ashleymills | 11:dfd1e0afcb7b | 33 | _readAddress = MMA8452_ADDRESS | 0x01; |
ashleymills | 11:dfd1e0afcb7b | 34 | _writeAddress = MMA8452_ADDRESS & 0xFE; |
ashleymills | 12:172540ff6b8b | 35 | |
ashleymills | 12:172540ff6b8b | 36 | // set some defaults |
ashleymills | 12:172540ff6b8b | 37 | _bitDepth = BIT_DEPTH_UNKNOWN; |
ashleymills | 12:172540ff6b8b | 38 | setBitDepth(BIT_DEPTH_12); |
ashleymills | 13:4bd8b4cd479d | 39 | _dynamicRange = DYNAMIC_RANGE_UNKNOWN; |
ashleymills | 13:4bd8b4cd479d | 40 | setDynamicRange(DYNAMIC_RANGE_2G); |
ashleymills | 13:4bd8b4cd479d | 41 | |
ashleymills | 11:dfd1e0afcb7b | 42 | DBG("Done"); |
nherriot | 0:bcf2aa85d7f9 | 43 | } |
nherriot | 0:bcf2aa85d7f9 | 44 | |
nherriot | 0:bcf2aa85d7f9 | 45 | |
nherriot | 0:bcf2aa85d7f9 | 46 | // Destroys instance |
ashleymills | 10:ca9ba7ad4e94 | 47 | MMA8452::~MMA8452() {} |
nherriot | 0:bcf2aa85d7f9 | 48 | |
nherriot | 0:bcf2aa85d7f9 | 49 | // Setting the control register bit 1 to true to activate the MMA8452 |
ashleymills | 10:ca9ba7ad4e94 | 50 | int MMA8452::activate() { |
ashleymills | 6:f6bde04bf8be | 51 | // perform write and return error code |
ashleymills | 12:172540ff6b8b | 52 | return logicalORRegister(MMA8452_CTRL_REG_1,MMA8452_ACTIVE_MASK); |
nherriot | 3:ffb0b1650ca2 | 53 | } |
nherriot | 3:ffb0b1650ca2 | 54 | |
ashleymills | 11:dfd1e0afcb7b | 55 | // Setting the control register bit 1 to 0 to standby the MMA8452 |
ashleymills | 11:dfd1e0afcb7b | 56 | int MMA8452::standby() { |
ashleymills | 11:dfd1e0afcb7b | 57 | // perform write and return error code |
ashleymills | 12:172540ff6b8b | 58 | return logicalANDRegister(MMA8452_CTRL_REG_1,MMA8452_STANDBY_MASK); |
nherriot | 5:b3d0abd97e55 | 59 | } |
nherriot | 5:b3d0abd97e55 | 60 | |
ashleymills | 11:dfd1e0afcb7b | 61 | // this reads a register, applies a bitmask with logical AND, sets a value with logical OR, |
ashleymills | 11:dfd1e0afcb7b | 62 | // and optionally goes into and out of standby at the beginning and end of the function respectively |
ashleymills | 11:dfd1e0afcb7b | 63 | int MMA8452::maskAndApplyRegister(char reg, char mask, char value, int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 64 | if(toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 65 | if(standby()) { |
ashleymills | 11:dfd1e0afcb7b | 66 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 67 | } |
ashleymills | 11:dfd1e0afcb7b | 68 | } |
ashleymills | 11:dfd1e0afcb7b | 69 | |
ashleymills | 11:dfd1e0afcb7b | 70 | // read from register |
ashleymills | 11:dfd1e0afcb7b | 71 | char oldValue = 0; |
ashleymills | 11:dfd1e0afcb7b | 72 | if(readRegister(reg,&oldValue)) { |
ashleymills | 11:dfd1e0afcb7b | 73 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 74 | } |
ashleymills | 11:dfd1e0afcb7b | 75 | |
ashleymills | 11:dfd1e0afcb7b | 76 | // apply bitmask |
ashleymills | 11:dfd1e0afcb7b | 77 | oldValue &= mask; |
ashleymills | 11:dfd1e0afcb7b | 78 | |
ashleymills | 11:dfd1e0afcb7b | 79 | // set value |
ashleymills | 11:dfd1e0afcb7b | 80 | oldValue |= value; |
ashleymills | 11:dfd1e0afcb7b | 81 | |
ashleymills | 11:dfd1e0afcb7b | 82 | // write back to register |
ashleymills | 11:dfd1e0afcb7b | 83 | if(writeRegister(reg,oldValue)) { |
ashleymills | 11:dfd1e0afcb7b | 84 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 85 | } |
ashleymills | 11:dfd1e0afcb7b | 86 | |
ashleymills | 11:dfd1e0afcb7b | 87 | if(toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 88 | if(activate()) { |
ashleymills | 11:dfd1e0afcb7b | 89 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 90 | } |
ashleymills | 11:dfd1e0afcb7b | 91 | } |
ashleymills | 11:dfd1e0afcb7b | 92 | return 0; |
nherriot | 0:bcf2aa85d7f9 | 93 | } |
nherriot | 0:bcf2aa85d7f9 | 94 | |
ashleymills | 11:dfd1e0afcb7b | 95 | int MMA8452::setDynamicRange(DynamicRange range, int toggleActivation) { |
ashleymills | 13:4bd8b4cd479d | 96 | _dynamicRange = range; |
ashleymills | 11:dfd1e0afcb7b | 97 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 98 | MMA8452_XYZ_DATA_CFG, |
ashleymills | 11:dfd1e0afcb7b | 99 | MMA8452_DYNAMIC_RANGE_MASK, |
ashleymills | 11:dfd1e0afcb7b | 100 | range, |
ashleymills | 11:dfd1e0afcb7b | 101 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 102 | ); |
nherriot | 0:bcf2aa85d7f9 | 103 | } |
nherriot | 0:bcf2aa85d7f9 | 104 | |
ashleymills | 11:dfd1e0afcb7b | 105 | int MMA8452::setDataRate(DataRateHz dataRate, int toggleActivation) { |
ashleymills | 11:dfd1e0afcb7b | 106 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 107 | MMA8452_CTRL_REG_1, |
ashleymills | 11:dfd1e0afcb7b | 108 | MMA8452_DATA_RATE_MASK, |
ashleymills | 11:dfd1e0afcb7b | 109 | dataRate<<MMA8452_DATA_RATE_MASK_SHIFT, |
ashleymills | 11:dfd1e0afcb7b | 110 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 111 | ); |
nherriot | 3:ffb0b1650ca2 | 112 | } |
nherriot | 3:ffb0b1650ca2 | 113 | |
ashleymills | 11:dfd1e0afcb7b | 114 | int MMA8452::setBitDepth(BitDepth depth,int toggleActivation) { |
ashleymills | 12:172540ff6b8b | 115 | _bitDepth = depth; |
ashleymills | 11:dfd1e0afcb7b | 116 | return maskAndApplyRegister( |
ashleymills | 11:dfd1e0afcb7b | 117 | MMA8452_CTRL_REG_1, |
ashleymills | 11:dfd1e0afcb7b | 118 | MMA8452_BIT_DEPTH_MASK, |
ashleymills | 11:dfd1e0afcb7b | 119 | depth<<MMA8452_BIT_DEPTH_MASK_SHIFT, |
ashleymills | 11:dfd1e0afcb7b | 120 | toggleActivation |
ashleymills | 11:dfd1e0afcb7b | 121 | ); |
nherriot | 3:ffb0b1650ca2 | 122 | } |
nherriot | 3:ffb0b1650ca2 | 123 | |
ashleymills | 12:172540ff6b8b | 124 | int MMA8452::isXYZReady() { |
ashleymills | 12:172540ff6b8b | 125 | char rval = 0; |
ashleymills | 12:172540ff6b8b | 126 | if(readRegister(MMA8452_STATUS,&rval)) { |
ashleymills | 12:172540ff6b8b | 127 | return 0; |
ashleymills | 12:172540ff6b8b | 128 | } |
ashleymills | 12:172540ff6b8b | 129 | return (rval&MMA8452_STATUS_ZYXDR_MASK); |
nherriot | 1:ef026bf28798 | 130 | } |
ashleymills | 12:172540ff6b8b | 131 | |
ashleymills | 12:172540ff6b8b | 132 | int MMA8452::getDeviceID(char *dst) { |
ashleymills | 12:172540ff6b8b | 133 | return readRegister(MMA8452_WHO_AM_I,dst); |
nherriot | 3:ffb0b1650ca2 | 134 | } |
nherriot | 3:ffb0b1650ca2 | 135 | |
ashleymills | 12:172540ff6b8b | 136 | int MMA8452::getStatus(char* dst) { |
ashleymills | 12:172540ff6b8b | 137 | return readRegister(MMA8452_STATUS,dst); |
nherriot | 3:ffb0b1650ca2 | 138 | } |
nherriot | 0:bcf2aa85d7f9 | 139 | |
ashleymills | 11:dfd1e0afcb7b | 140 | MMA8452::DynamicRange MMA8452::getDynamicRange() { |
ashleymills | 11:dfd1e0afcb7b | 141 | char rval = 0; |
ashleymills | 12:172540ff6b8b | 142 | if(readRegister(MMA8452_XYZ_DATA_CFG,&rval)) { |
ashleymills | 11:dfd1e0afcb7b | 143 | return MMA8452::DYNAMIC_RANGE_UNKNOWN; |
ashleymills | 11:dfd1e0afcb7b | 144 | } |
ashleymills | 11:dfd1e0afcb7b | 145 | rval &= (MMA8452_DYNAMIC_RANGE_MASK^0xFF); |
ashleymills | 11:dfd1e0afcb7b | 146 | return (MMA8452::DynamicRange)rval; |
ashleymills | 11:dfd1e0afcb7b | 147 | } |
ashleymills | 11:dfd1e0afcb7b | 148 | |
ashleymills | 11:dfd1e0afcb7b | 149 | MMA8452::DataRateHz MMA8452::getDataRate() { |
ashleymills | 11:dfd1e0afcb7b | 150 | char rval = 0; |
ashleymills | 11:dfd1e0afcb7b | 151 | if(readRegister(MMA8452_CTRL_REG_1,&rval)) { |
ashleymills | 11:dfd1e0afcb7b | 152 | return MMA8452::RATE_UNKNOWN; |
ashleymills | 11:dfd1e0afcb7b | 153 | } |
ashleymills | 11:dfd1e0afcb7b | 154 | // logical AND with inverse of mask |
ashleymills | 11:dfd1e0afcb7b | 155 | rval = rval&(MMA8452_DATA_RATE_MASK^0xFF); |
ashleymills | 11:dfd1e0afcb7b | 156 | // shift back into position |
ashleymills | 11:dfd1e0afcb7b | 157 | rval >>= MMA8452_DATA_RATE_MASK_SHIFT; |
ashleymills | 11:dfd1e0afcb7b | 158 | return (MMA8452::DataRateHz)rval; |
ashleymills | 11:dfd1e0afcb7b | 159 | } |
ashleymills | 11:dfd1e0afcb7b | 160 | |
nherriot | 0:bcf2aa85d7f9 | 161 | // Reads xyz |
ashleymills | 13:4bd8b4cd479d | 162 | int MMA8452::readXYZRaw(char *dst) { |
ashleymills | 12:172540ff6b8b | 163 | if(_bitDepth==BIT_DEPTH_UNKNOWN) { |
ashleymills | 12:172540ff6b8b | 164 | return 1; |
ashleymills | 12:172540ff6b8b | 165 | } |
ashleymills | 12:172540ff6b8b | 166 | int readLen = 3; |
ashleymills | 12:172540ff6b8b | 167 | if(_bitDepth==BIT_DEPTH_12) { |
ashleymills | 12:172540ff6b8b | 168 | readLen = 6; |
ashleymills | 12:172540ff6b8b | 169 | } |
ashleymills | 12:172540ff6b8b | 170 | return readRegister(MMA8452_OUT_X_MSB,dst,readLen); |
nherriot | 1:ef026bf28798 | 171 | } |
nherriot | 0:bcf2aa85d7f9 | 172 | |
ashleymills | 13:4bd8b4cd479d | 173 | int MMA8452::readXYZCounts(int *x, int *y, int *z) { |
ashleymills | 13:4bd8b4cd479d | 174 | char buf[6]; |
ashleymills | 13:4bd8b4cd479d | 175 | if(readXYZRaw((char*)&buf)) { |
ashleymills | 13:4bd8b4cd479d | 176 | return 1; |
ashleymills | 13:4bd8b4cd479d | 177 | } |
ashleymills | 13:4bd8b4cd479d | 178 | if(_bitDepth==BIT_DEPTH_12) { |
ashleymills | 13:4bd8b4cd479d | 179 | *x = twelveBitToSigned(&buf[0]); |
ashleymills | 13:4bd8b4cd479d | 180 | *y = twelveBitToSigned(&buf[2]); |
ashleymills | 13:4bd8b4cd479d | 181 | *z = twelveBitToSigned(&buf[4]); |
ashleymills | 13:4bd8b4cd479d | 182 | } else { |
ashleymills | 13:4bd8b4cd479d | 183 | *x = eightBitToSigned(&buf[0]); |
ashleymills | 13:4bd8b4cd479d | 184 | *y = eightBitToSigned(&buf[1]); |
ashleymills | 13:4bd8b4cd479d | 185 | *z = eightBitToSigned(&buf[2]); |
ashleymills | 13:4bd8b4cd479d | 186 | } |
ashleymills | 13:4bd8b4cd479d | 187 | |
ashleymills | 13:4bd8b4cd479d | 188 | return 0; |
ashleymills | 13:4bd8b4cd479d | 189 | } |
ashleymills | 13:4bd8b4cd479d | 190 | |
ashleymills | 13:4bd8b4cd479d | 191 | double MMA8452::convertCountToGravity(int count, int countsPerG) { |
ashleymills | 13:4bd8b4cd479d | 192 | return (double)count/(double)countsPerG; |
ashleymills | 13:4bd8b4cd479d | 193 | } |
ashleymills | 13:4bd8b4cd479d | 194 | |
ashleymills | 13:4bd8b4cd479d | 195 | int MMA8452::readXYZGravity(double *x, double *y, double *z) { |
ashleymills | 13:4bd8b4cd479d | 196 | int xCount = 0, yCount = 0, zCount = 0; |
ashleymills | 13:4bd8b4cd479d | 197 | if(readXYZCounts(&xCount,&yCount,&zCount)) { |
ashleymills | 13:4bd8b4cd479d | 198 | return 1; |
ashleymills | 13:4bd8b4cd479d | 199 | } |
ashleymills | 13:4bd8b4cd479d | 200 | |
ashleymills | 13:4bd8b4cd479d | 201 | // assume starting with DYNAMIC_RANGE_2G and BIT_DEPTH_12 |
ashleymills | 13:4bd8b4cd479d | 202 | int countsPerG = 1024; |
ashleymills | 13:4bd8b4cd479d | 203 | if(_bitDepth==BIT_DEPTH_8) { |
ashleymills | 13:4bd8b4cd479d | 204 | countsPerG = 64; |
ashleymills | 13:4bd8b4cd479d | 205 | } |
ashleymills | 13:4bd8b4cd479d | 206 | switch(_dynamicRange) { |
ashleymills | 13:4bd8b4cd479d | 207 | case DYNAMIC_RANGE_4G: |
ashleymills | 13:4bd8b4cd479d | 208 | countsPerG /= 2; |
ashleymills | 13:4bd8b4cd479d | 209 | break; |
ashleymills | 13:4bd8b4cd479d | 210 | case DYNAMIC_RANGE_8G: |
ashleymills | 13:4bd8b4cd479d | 211 | countsPerG /= 4; |
ashleymills | 13:4bd8b4cd479d | 212 | break; |
ashleymills | 13:4bd8b4cd479d | 213 | } |
ashleymills | 13:4bd8b4cd479d | 214 | |
ashleymills | 13:4bd8b4cd479d | 215 | *x = convertCountToGravity(xCount,countsPerG); |
ashleymills | 13:4bd8b4cd479d | 216 | *y = convertCountToGravity(yCount,countsPerG); |
ashleymills | 13:4bd8b4cd479d | 217 | *z = convertCountToGravity(zCount,countsPerG); |
ashleymills | 13:4bd8b4cd479d | 218 | return 0; |
ashleymills | 13:4bd8b4cd479d | 219 | } |
ashleymills | 13:4bd8b4cd479d | 220 | |
ashleymills | 11:dfd1e0afcb7b | 221 | // apply an AND mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 222 | int MMA8452::logicalANDRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 223 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 224 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 225 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 226 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 227 | } |
ashleymills | 11:dfd1e0afcb7b | 228 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 229 | value &= mask; |
ashleymills | 11:dfd1e0afcb7b | 230 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 231 | } |
ashleymills | 11:dfd1e0afcb7b | 232 | |
ashleymills | 11:dfd1e0afcb7b | 233 | |
ashleymills | 11:dfd1e0afcb7b | 234 | // apply an OR mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 235 | int MMA8452::logicalORRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 236 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 237 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 238 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 239 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 240 | } |
ashleymills | 11:dfd1e0afcb7b | 241 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 242 | value |= mask; |
ashleymills | 11:dfd1e0afcb7b | 243 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 244 | } |
ashleymills | 11:dfd1e0afcb7b | 245 | |
ashleymills | 11:dfd1e0afcb7b | 246 | // apply an OR mask to a register. read register value, apply mask, write it back |
ashleymills | 11:dfd1e0afcb7b | 247 | int MMA8452::logicalXORRegister(char addr, char mask) { |
ashleymills | 11:dfd1e0afcb7b | 248 | char value = 0; |
ashleymills | 11:dfd1e0afcb7b | 249 | // read register value |
ashleymills | 11:dfd1e0afcb7b | 250 | if(readRegister(addr,&value)) { |
ashleymills | 11:dfd1e0afcb7b | 251 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 252 | } |
ashleymills | 11:dfd1e0afcb7b | 253 | // apply mask |
ashleymills | 11:dfd1e0afcb7b | 254 | value ^= mask; |
ashleymills | 11:dfd1e0afcb7b | 255 | return writeRegister(addr,value); |
ashleymills | 11:dfd1e0afcb7b | 256 | } |
ashleymills | 11:dfd1e0afcb7b | 257 | |
ashleymills | 11:dfd1e0afcb7b | 258 | // Write register (The device must be placed in Standby Mode to change the value of the registers) |
ashleymills | 11:dfd1e0afcb7b | 259 | int MMA8452::writeRegister(char addr, char data) { |
ashleymills | 11:dfd1e0afcb7b | 260 | // what this actually does is the following |
ashleymills | 11:dfd1e0afcb7b | 261 | // 1. tell I2C bus to start transaction |
ashleymills | 11:dfd1e0afcb7b | 262 | // 2. tell slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 263 | // 3. send the write address |
ashleymills | 11:dfd1e0afcb7b | 264 | // 4. send the data to write |
ashleymills | 11:dfd1e0afcb7b | 265 | // 5. tell I2C bus to end transaction |
ashleymills | 11:dfd1e0afcb7b | 266 | |
ashleymills | 11:dfd1e0afcb7b | 267 | // we can wrap this up in the I2C library write function |
ashleymills | 11:dfd1e0afcb7b | 268 | char buf[2] = {0,0}; |
ashleymills | 11:dfd1e0afcb7b | 269 | buf[0] = addr; |
ashleymills | 11:dfd1e0afcb7b | 270 | buf[1] = data; |
ashleymills | 11:dfd1e0afcb7b | 271 | return _i2c.write(MMA8452_ADDRESS, buf,2); |
ashleymills | 11:dfd1e0afcb7b | 272 | // note, could also do return writeRegister(addr,&data,1); |
nherriot | 0:bcf2aa85d7f9 | 273 | } |
nherriot | 0:bcf2aa85d7f9 | 274 | |
ashleymills | 13:4bd8b4cd479d | 275 | int MMA8452::eightBitToSigned(char *buf) { |
ashleymills | 13:4bd8b4cd479d | 276 | return (int8_t)*buf; |
ashleymills | 13:4bd8b4cd479d | 277 | } |
ashleymills | 13:4bd8b4cd479d | 278 | |
ashleymills | 13:4bd8b4cd479d | 279 | int MMA8452::twelveBitToSigned(char *buf) { |
ashleymills | 13:4bd8b4cd479d | 280 | // cheat by using the int16_t internal type |
ashleymills | 13:4bd8b4cd479d | 281 | // all we need to do is convert to little-endian format and shift right |
ashleymills | 13:4bd8b4cd479d | 282 | int16_t x = 0; |
ashleymills | 13:4bd8b4cd479d | 283 | ((char*)&x)[1] = buf[0]; |
ashleymills | 13:4bd8b4cd479d | 284 | ((char*)&x)[0] = buf[1]; |
ashleymills | 13:4bd8b4cd479d | 285 | // note this only works because the below is an arithmetic right shift |
ashleymills | 13:4bd8b4cd479d | 286 | return x>>4; |
ashleymills | 13:4bd8b4cd479d | 287 | } |
ashleymills | 11:dfd1e0afcb7b | 288 | |
ashleymills | 11:dfd1e0afcb7b | 289 | int MMA8452::writeRegister(char addr, char *data, int nbytes) { |
ashleymills | 11:dfd1e0afcb7b | 290 | // writing multiple bytes is a little bit annoying because |
ashleymills | 11:dfd1e0afcb7b | 291 | // the I2C library doesn't support sending the address separately |
ashleymills | 11:dfd1e0afcb7b | 292 | // so we just do it manually |
nherriot | 0:bcf2aa85d7f9 | 293 | |
ashleymills | 11:dfd1e0afcb7b | 294 | // 1. tell I2C bus to start transaction |
ashleymills | 11:dfd1e0afcb7b | 295 | _i2c.start(); |
ashleymills | 11:dfd1e0afcb7b | 296 | // 2. tell slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 297 | if(_i2c.write(_writeAddress)!=1) { |
ashleymills | 11:dfd1e0afcb7b | 298 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 299 | } |
ashleymills | 11:dfd1e0afcb7b | 300 | // 3. send the write address |
ashleymills | 11:dfd1e0afcb7b | 301 | if(_i2c.write(addr)!=1) { |
ashleymills | 11:dfd1e0afcb7b | 302 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 303 | } |
ashleymills | 11:dfd1e0afcb7b | 304 | // 4. send the data to write |
ashleymills | 11:dfd1e0afcb7b | 305 | for(int i=0; i<nbytes; i++) { |
ashleymills | 11:dfd1e0afcb7b | 306 | if(_i2c.write(data[i])!=1) { |
ashleymills | 11:dfd1e0afcb7b | 307 | return 1; |
ashleymills | 11:dfd1e0afcb7b | 308 | } |
ashleymills | 11:dfd1e0afcb7b | 309 | } |
ashleymills | 11:dfd1e0afcb7b | 310 | // 5. tell I2C bus to end transaction |
ashleymills | 11:dfd1e0afcb7b | 311 | _i2c.stop(); |
ashleymills | 11:dfd1e0afcb7b | 312 | return 0; |
ashleymills | 11:dfd1e0afcb7b | 313 | } |
ashleymills | 11:dfd1e0afcb7b | 314 | |
ashleymills | 11:dfd1e0afcb7b | 315 | int MMA8452::readRegister(char addr, char *dst, int nbytes) { |
ashleymills | 11:dfd1e0afcb7b | 316 | // this is a bit odd, but basically proceeds like this |
ashleymills | 11:dfd1e0afcb7b | 317 | // 1. Send a start command |
ashleymills | 11:dfd1e0afcb7b | 318 | // 2. Tell the slave we want to write (slave address & write flag) |
ashleymills | 11:dfd1e0afcb7b | 319 | // 3. Send the address of the register (addr) |
ashleymills | 11:dfd1e0afcb7b | 320 | // 4. Send another start command to delineate read portion |
ashleymills | 11:dfd1e0afcb7b | 321 | // 5. Tell the slave we want to read (slave address & read flag) |
ashleymills | 11:dfd1e0afcb7b | 322 | // 6. Read the register value bytes |
ashleymills | 11:dfd1e0afcb7b | 323 | // 7. Send a stop command |
ashleymills | 11:dfd1e0afcb7b | 324 | |
ashleymills | 11:dfd1e0afcb7b | 325 | // we can wrap this process in the I2C library read and write commands |
ashleymills | 11:dfd1e0afcb7b | 326 | if(_i2c.write(MMA8452_ADDRESS,&addr,1,true)) { |
ashleymills | 11:dfd1e0afcb7b | 327 | return 1; |
ashleymills | 8:89272163f395 | 328 | } |
ashleymills | 11:dfd1e0afcb7b | 329 | return _i2c.read(MMA8452_ADDRESS,dst,nbytes); |
ashleymills | 11:dfd1e0afcb7b | 330 | } |
ashleymills | 11:dfd1e0afcb7b | 331 | |
ashleymills | 11:dfd1e0afcb7b | 332 | // most registers are 1 byte, so here is a convenience function |
ashleymills | 11:dfd1e0afcb7b | 333 | int MMA8452::readRegister(char addr, char *dst) { |
ashleymills | 11:dfd1e0afcb7b | 334 | return readRegister(addr,dst,1); |
nherriot | 0:bcf2aa85d7f9 | 335 | } |
ashleymills | 11:dfd1e0afcb7b | 336 | |
ashleymills | 11:dfd1e0afcb7b | 337 | void MMA8452::debugRegister(char reg) { |
ashleymills | 11:dfd1e0afcb7b | 338 | // get register value |
ashleymills | 11:dfd1e0afcb7b | 339 | char v = 0; |
ashleymills | 11:dfd1e0afcb7b | 340 | if(readRegister(reg,&v)) { |
ashleymills | 12:172540ff6b8b | 341 | DBG("Error reading specified register"); |
ashleymills | 11:dfd1e0afcb7b | 342 | return; |
ashleymills | 11:dfd1e0afcb7b | 343 | } |
ashleymills | 11:dfd1e0afcb7b | 344 | // print out details |
ashleymills | 11:dfd1e0afcb7b | 345 | switch(reg) { |
ashleymills | 11:dfd1e0afcb7b | 346 | case MMA8452_CTRL_REG_1: |
ashleymills | 11:dfd1e0afcb7b | 347 | DBG("CTRL_REG_1 has value: 0x%x",v); |
ashleymills | 11:dfd1e0afcb7b | 348 | DBG(" 7 ALSP_RATE_1: %d",(v&0x80)>>7); |
ashleymills | 11:dfd1e0afcb7b | 349 | DBG(" 6 ALSP_RATE_0: %d",(v&0x40)>>6); |
ashleymills | 11:dfd1e0afcb7b | 350 | DBG(" 5 DR2: %d", (v&0x20)>>5); |
ashleymills | 11:dfd1e0afcb7b | 351 | DBG(" 4 DR1: %d", (v&0x10)>>4); |
ashleymills | 11:dfd1e0afcb7b | 352 | DBG(" 3 DR0: %d", (v&0x08)>>3); |
ashleymills | 11:dfd1e0afcb7b | 353 | DBG(" 2 LNOISE: %d", (v&0x04)>>2); |
ashleymills | 11:dfd1e0afcb7b | 354 | DBG(" 1 FREAD: %d", (v&0x02)>>1); |
ashleymills | 11:dfd1e0afcb7b | 355 | DBG(" 0 ACTIVE: %d", (v&0x01)); |
ashleymills | 11:dfd1e0afcb7b | 356 | break; |
ashleymills | 11:dfd1e0afcb7b | 357 | |
ashleymills | 11:dfd1e0afcb7b | 358 | case MMA8452_XYZ_DATA_CFG: |
ashleymills | 11:dfd1e0afcb7b | 359 | DBG("XYZ_DATA_CFG has value: 0x%x",v); |
ashleymills | 11:dfd1e0afcb7b | 360 | DBG(" 7 Unused: %d", (v&0x80)>>7); |
ashleymills | 11:dfd1e0afcb7b | 361 | DBG(" 6 0: %d", (v&0x40)>>6); |
ashleymills | 11:dfd1e0afcb7b | 362 | DBG(" 5 0: %d", (v&0x20)>>5); |
ashleymills | 11:dfd1e0afcb7b | 363 | DBG(" 4 HPF_Out: %d",(v&0x10)>>4); |
ashleymills | 11:dfd1e0afcb7b | 364 | DBG(" 3 0: %d", (v&0x08)>>3); |
ashleymills | 11:dfd1e0afcb7b | 365 | DBG(" 2 0: %d", (v&0x04)>>2); |
ashleymills | 11:dfd1e0afcb7b | 366 | DBG(" 1 FS1: %d", (v&0x02)>>1); |
ashleymills | 11:dfd1e0afcb7b | 367 | DBG(" 0 FS0: %d", (v&0x01)); |
ashleymills | 11:dfd1e0afcb7b | 368 | switch(v&0x03) { |
ashleymills | 11:dfd1e0afcb7b | 369 | case 0: |
ashleymills | 11:dfd1e0afcb7b | 370 | DBG("Dynamic range: 2G"); |
ashleymills | 11:dfd1e0afcb7b | 371 | break; |
ashleymills | 11:dfd1e0afcb7b | 372 | case 1: |
ashleymills | 11:dfd1e0afcb7b | 373 | DBG("Dynamic range: 4G"); |
ashleymills | 11:dfd1e0afcb7b | 374 | break; |
ashleymills | 11:dfd1e0afcb7b | 375 | case 2: |
ashleymills | 11:dfd1e0afcb7b | 376 | DBG("Dynamic range: 8G"); |
ashleymills | 11:dfd1e0afcb7b | 377 | break; |
ashleymills | 11:dfd1e0afcb7b | 378 | default: |
ashleymills | 11:dfd1e0afcb7b | 379 | DBG("Unknown dynamic range"); |
ashleymills | 11:dfd1e0afcb7b | 380 | break; |
ashleymills | 11:dfd1e0afcb7b | 381 | } |
ashleymills | 11:dfd1e0afcb7b | 382 | break; |
ashleymills | 11:dfd1e0afcb7b | 383 | |
ashleymills | 12:172540ff6b8b | 384 | case MMA8452_STATUS: |
ashleymills | 12:172540ff6b8b | 385 | DBG("STATUS has value: 0x%x",v); |
ashleymills | 12:172540ff6b8b | 386 | DBG(" 7 ZYXOW: %d",(v&0x80)>>7); |
ashleymills | 12:172540ff6b8b | 387 | DBG(" 6 ZOW: %d", (v&0x40)>>6); |
ashleymills | 12:172540ff6b8b | 388 | DBG(" 5 YOW: %d", (v&0x20)>>5); |
ashleymills | 12:172540ff6b8b | 389 | DBG(" 4 XOW: %d", (v&0x10)>>4); |
ashleymills | 12:172540ff6b8b | 390 | DBG(" 3 ZYXDR: %d",(v&0x08)>>3); |
ashleymills | 12:172540ff6b8b | 391 | DBG(" 2 ZDR: %d", (v&0x04)>>2); |
ashleymills | 12:172540ff6b8b | 392 | DBG(" 1 YDR: %d", (v&0x02)>>1); |
ashleymills | 12:172540ff6b8b | 393 | DBG(" 0 XDR: %d", (v&0x01)); |
ashleymills | 12:172540ff6b8b | 394 | break; |
ashleymills | 12:172540ff6b8b | 395 | |
ashleymills | 11:dfd1e0afcb7b | 396 | default: |
ashleymills | 11:dfd1e0afcb7b | 397 | DBG("Unknown register address: 0x%x",reg); |
ashleymills | 11:dfd1e0afcb7b | 398 | break; |
ashleymills | 11:dfd1e0afcb7b | 399 | } |
ashleymills | 11:dfd1e0afcb7b | 400 | } |