1 | #include <L3G.h>
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2 | #include <Wire.h>
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3 | #include <math.h>
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4 |
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5 | // Defines ////////////////////////////////////////////////////////////////
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6 |
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7 | // The Arduino two-wire interface uses a 7-bit number for the address,
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8 | // and sets the last bit correctly based on reads and writes
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9 | #define D20_SA0_HIGH_ADDRESS 0b1101011 // also applies to D20H
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10 | #define D20_SA0_LOW_ADDRESS 0b1101010 // also applies to D20H
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11 | #define L3G4200D_SA0_HIGH_ADDRESS 0b1101001
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12 | #define L3G4200D_SA0_LOW_ADDRESS 0b1101000
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13 |
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14 | #define TEST_REG_ERROR -1
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15 |
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16 | #define D20H_WHO_ID 0xD7
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17 | #define D20_WHO_ID 0xD4
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18 | #define L3G4200D_WHO_ID 0xD3
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19 |
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20 | // Constructors ////////////////////////////////////////////////////////////////
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21 |
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22 | L3G::L3G(void)
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23 | {
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24 | _device = device_auto;
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25 |
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26 | io_timeout = 0; // 0 = no timeout
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27 | did_timeout = false;
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28 | }
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29 |
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30 | // Public Methods //////////////////////////////////////////////////////////////
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31 |
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32 | // Did a timeout occur in read() since the last call to timeoutOccurred()?
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33 | bool L3G::timeoutOccurred()
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34 | {
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35 | bool tmp = did_timeout;
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36 | did_timeout = false;
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37 | return tmp;
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38 | }
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39 |
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40 | void L3G::setTimeout(unsigned int timeout)
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41 | {
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42 | io_timeout = timeout;
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43 | }
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44 |
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45 | unsigned int L3G::getTimeout()
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46 | {
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47 | return io_timeout;
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48 | }
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49 |
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50 | bool L3G::init(deviceType device, sa0State sa0)
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51 | {
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52 | int id;
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53 |
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54 | // perform auto-detection unless device type and SA0 state were both specified
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55 | if (device == device_auto || sa0 == sa0_auto)
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56 | {
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57 | // check for L3GD20H, D20 if device is unidentified or was specified to be one of these types
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58 | if (device == device_auto || device == device_D20H || device == device_D20)
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59 | {
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60 | // check SA0 high address unless SA0 was specified to be low
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61 | if (sa0 != sa0_low && (id = testReg(D20_SA0_HIGH_ADDRESS, WHO_AM_I)) != TEST_REG_ERROR)
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62 | {
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63 | // device responds to address 1101011; it's a D20H or D20 with SA0 high
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64 | sa0 = sa0_high;
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65 | if (device == device_auto)
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66 | {
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67 | // use ID from WHO_AM_I register to determine device type
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68 | device = (id == D20H_WHO_ID) ? device_D20H : device_D20;
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69 | }
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70 | }
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71 | // check SA0 low address unless SA0 was specified to be high
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72 | else if (sa0 != sa0_high && (id = testReg(D20_SA0_LOW_ADDRESS, WHO_AM_I)) != TEST_REG_ERROR)
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73 | {
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74 | // device responds to address 1101010; it's a D20H or D20 with SA0 low
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75 | sa0 = sa0_low;
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76 | if (device == device_auto)
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77 | {
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78 | // use ID from WHO_AM_I register to determine device type
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79 | device = (id == D20H_WHO_ID) ? device_D20H : device_D20;
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80 | }
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81 | }
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82 | }
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83 |
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84 | // check for L3G4200D if device is still unidentified or was specified to be this type
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85 | if (device == device_auto || device == device_4200D)
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86 | {
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87 | if (sa0 != sa0_low && testReg(L3G4200D_SA0_HIGH_ADDRESS, WHO_AM_I) == L3G4200D_WHO_ID)
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88 | {
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89 | // device responds to address 1101001; it's a 4200D with SA0 high
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90 | device = device_4200D;
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91 | sa0 = sa0_high;
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92 | }
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93 | else if (sa0 != sa0_high && testReg(L3G4200D_SA0_LOW_ADDRESS, WHO_AM_I) == L3G4200D_WHO_ID)
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94 | {
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95 | // device responds to address 1101000; it's a 4200D with SA0 low
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96 | device = device_4200D;
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97 | sa0 = sa0_low;
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98 | }
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99 | }
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100 |
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101 | // make sure device and SA0 were successfully detected; otherwise, indicate failure
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102 | if (device == device_auto || sa0 == sa0_auto)
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103 | {
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104 | return false;
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105 | }
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106 | }
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107 |
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108 | _device = device;
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109 |
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110 | // set device address
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111 | switch (device)
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112 | {
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113 | case device_D20H:
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114 | case device_D20:
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115 | address = (sa0 == sa0_high) ? D20_SA0_HIGH_ADDRESS : D20_SA0_LOW_ADDRESS;
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116 | break;
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117 |
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118 | case device_4200D:
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119 | address = (sa0 == sa0_high) ? L3G4200D_SA0_HIGH_ADDRESS : L3G4200D_SA0_LOW_ADDRESS;
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120 | break;
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121 | }
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122 |
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123 | return true;
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124 | }
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125 |
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126 | /*
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127 | Enables the L3G's gyro. Also:
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128 | - Sets gyro full scale (gain) to default power-on value of +/- 250 dps
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129 | (specified as +/- 245 dps for L3GD20H).
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130 | - Selects 200 Hz ODR (output data rate). (Exact rate is specified as 189.4 Hz
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131 | for L3GD20H and 190 Hz for L3GD20.)
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132 | Note that this function will also reset other settings controlled by
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133 | the registers it writes to.
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134 | */
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135 | void L3G::enableDefault(void)
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136 | {
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137 | if (_device == device_D20H)
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138 | {
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139 | // 0x00 = 0b00000000
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140 | // Low_ODR = 0 (low speed ODR disabled)
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141 | writeReg(LOW_ODR, 0x00);
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142 | }
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143 |
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144 | // 0x00 = 0b00000000
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145 | // FS = 00 (+/- 250 dps full scale)
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146 | writeReg(CTRL_REG4, 0x00);
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147 |
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148 | // 0x6F = 0b01101111
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149 | // DR = 01 (200 Hz ODR); BW = 10 (50 Hz bandwidth); PD = 1 (normal mode); Zen = Yen = Xen = 1 (all axes enabled)
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150 | writeReg(CTRL_REG1, 0x6F);
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151 | }
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152 |
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153 | // Writes a gyro register
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154 | void L3G::writeReg(byte reg, byte value)
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155 | {
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156 | Wire.beginTransmission(address);
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157 | Wire.write(reg);
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158 | Wire.write(value);
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159 | last_status = Wire.endTransmission();
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160 | }
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161 |
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162 | // Reads a gyro register
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163 | byte L3G::readReg(byte reg)
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164 | {
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165 | byte value;
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166 |
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167 | Wire.beginTransmission(address);
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168 | Wire.write(reg);
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169 | last_status = Wire.endTransmission();
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170 | Wire.requestFrom(address, (byte)1);
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171 | value = Wire.read();
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172 | Wire.endTransmission();
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173 |
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174 | return value;
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175 | }
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176 |
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177 | // Reads the 3 gyro channels and stores them in vector g
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178 | void L3G::read()
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179 | {
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180 | Wire.beginTransmission(address);
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181 | // assert the MSB of the address to get the gyro
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182 | // to do slave-transmit subaddress updating.
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183 | Wire.write(OUT_X_L | (1 << 7));
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184 | Wire.endTransmission();
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185 | Wire.requestFrom(address, (byte)6);
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186 |
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187 | unsigned int millis_start = millis();
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188 | while (Wire.available() < 6)
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189 | {
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190 | if (io_timeout > 0 && ((unsigned int)millis() - millis_start) > io_timeout)
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191 | {
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192 | did_timeout = true;
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193 | return;
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194 | }
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195 | }
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196 |
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197 | uint8_t xlg = Wire.read();
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198 | uint8_t xhg = Wire.read();
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199 | uint8_t ylg = Wire.read();
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200 | uint8_t yhg = Wire.read();
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201 | uint8_t zlg = Wire.read();
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202 | uint8_t zhg = Wire.read();
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203 |
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204 | // combine high and low bytes
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205 | g.x = (int16_t)(xhg << 8 | xlg);
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206 | g.y = (int16_t)(yhg << 8 | ylg);
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207 | g.z = (int16_t)(zhg << 8 | zlg);
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208 | }
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209 |
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210 | void L3G::vector_normalize(vector<float> *a)
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211 | {
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212 | float mag = sqrt(vector_dot(a,a));
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213 | a->x /= mag;
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214 | a->y /= mag;
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215 | a->z /= mag;
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216 | }
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217 |
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218 | // Private Methods //////////////////////////////////////////////////////////////
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219 |
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220 | int L3G::testReg(byte address, regAddr reg)
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221 | {
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222 | Wire.beginTransmission(address);
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223 | Wire.write((byte)reg);
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224 | if (Wire.endTransmission() != 0)
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225 | {
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226 | return TEST_REG_ERROR;
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227 | }
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228 |
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229 | Wire.requestFrom(address, (byte)1);
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230 | if (Wire.available())
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231 | {
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232 | return Wire.read();
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233 | }
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234 | else
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235 | {
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236 | return TEST_REG_ERROR;
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237 | }
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238 | }
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