root / branches / colonetmk2 / code / projects / libdragonfly / encoders.c @ 1456
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1 | 868 | justin | #include "encoders.h" |
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2 | #include "spi.h" |
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3 | #include "ring_buffer.h" |
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4 | 1456 | rcahoon | #include <avr/io.h> |
5 | 868 | justin | |
6 | unsigned int left_data_buf; |
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7 | unsigned int right_data_buf; |
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8 | char encoder_buf_index;
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9 | |||
10 | unsigned int left_data; |
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11 | unsigned int right_data; |
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12 | |||
13 | unsigned int left_data_array[BUFFER_SIZE]; |
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14 | unsigned int right_data_array[BUFFER_SIZE]; |
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15 | int left_data_idx;
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16 | int right_data_idx;
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17 | |||
18 | int left_dx;
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19 | int right_dx;
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20 | long int timecount; |
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21 | |||
22 | volatile short int data_ready; |
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23 | |||
24 | void encoder_recv(char data); |
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25 | |||
26 | //Helper Function Prototypes
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27 | inline void left_data_array_put(unsigned short int value); |
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28 | inline unsigned int left_data_array_top(void); |
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29 | inline unsigned int left_data_array_prev(void); |
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30 | inline unsigned int left_data_array_bottom(void); |
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31 | |||
32 | inline void right_data_array_put(unsigned short int value); |
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33 | inline unsigned int right_data_array_top(void); |
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34 | inline unsigned int right_data_array_prev(void); |
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35 | inline unsigned int right_data_array_bottom(void); |
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36 | |||
37 | 1418 | chihsiuh | //encoder_get_v helper function prototypes
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38 | int left_data_at(int index); |
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39 | int right_data_at(int index); |
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40 | int get_dx(char encoder, int index); |
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41 | 868 | justin | |
42 | 890 | justin | void encoder_recv_complete(void){ |
43 | 868 | justin | encoder_buf_index = 0;
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44 | data_ready++; |
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45 | |||
46 | spi_transfer(5);
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47 | } |
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48 | |||
49 | /**
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50 | * @brief Initializes encoder variables and the hardware interface.
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51 | */
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52 | void encoders_init(void){ |
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53 | int i;
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54 | |||
55 | data_ready=0;
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56 | |||
57 | spi_init(encoder_recv, encoder_recv_complete); |
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58 | encoder_buf_index = 0;
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59 | left_data_buf = 0;
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60 | right_data_buf= 0;
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61 | left_data = -1;
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62 | right_data = -1;
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63 | |||
64 | //RING_BUFFER_INIT(enc_buffer,BUFFER_SIZE);
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65 | left_data_idx = 0;
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66 | right_data_idx = 0;
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67 | for(i = 0; i < BUFFER_SIZE; i++) { |
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68 | left_data_array[i] = 0;
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69 | } |
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70 | for(i = 0; i < BUFFER_SIZE; i++) { |
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71 | right_data_array[i] = 0;
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72 | } |
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73 | spi_transfer(5);
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74 | } |
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75 | |||
76 | /**
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77 | * @brief Returns the specified encoders value
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78 | *
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79 | * @param encoder this is the encoder that you want to read. Valid arguments
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80 | * are LEFT and RIGHT
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81 | *
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82 | 1418 | chihsiuh | * @return the value of the specified encoder.
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83 | * -1 usually means low battery.
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84 | * values above ENCODER_MAX usually means phyiscal problems with
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85 | * the encoder.
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86 | 868 | justin | **/
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87 | int encoder_read(char encoder){ |
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88 | |||
89 | if(encoder==LEFT) return left_data; |
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90 | else if(encoder==RIGHT) return right_data; |
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91 | else return -1; |
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92 | } |
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93 | |||
94 | /**
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95 | 1418 | chihsiuh | * @brief Get total distance travelled by the specified encoder (in encoder ticks)
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96 | *
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97 | * @param encoder the encoder that you want to read, either LEFT or RIGHT
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98 | *
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99 | * @return The distance covered by the specified encoder.
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100 | *
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101 | * @note Simply calls encoder_get_dx.
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102 | **/
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103 | int encoder_get_x(char encoder) { |
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104 | return encoder_get_dx(encoder);
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105 | } |
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106 | |||
107 | /**
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108 | 868 | justin | * Gets the total distance covered by the specified encoder (in encoder clicks)
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109 | *
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110 | * @param encoder the encoder that you want to read, use LEFT or RIGHT
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111 | *
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112 | * @return The distance covered by the specified encoder.
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113 | **/
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114 | int encoder_get_dx(char encoder) { |
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115 | |||
116 | if(encoder==LEFT) return left_dx; |
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117 | else if(encoder==RIGHT) return right_dx; |
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118 | else return -1; |
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119 | } |
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120 | |||
121 | 1418 | chihsiuh | /**
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122 | * @brief Returns the approximated instantaneous velocity of the robot
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123 | * in terms of encoder clicks.
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124 | *
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125 | * @param encoder RIGHT or LEFT - the wheel you want the velocity for.
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126 | *
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127 | * @return The instantaneous velocity for the given wheel or twice the ERR_VEL
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128 | * if an error occurs (1024 * 2 = 2048)
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129 | *
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130 | * @bug This uses hard coded values and results are inconsistent.
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131 | * Use at your own risk.
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132 | */
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133 | int encoder_get_v(char encoder){ |
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134 | int vel1, vel2;
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135 | vel1 = get_dx(encoder, 0);
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136 | vel2 = get_dx(encoder, 1);
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137 | |||
138 | if (vel1 == ERR_VEL && vel2 == ERR_VEL)
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139 | return ERR_VEL << 1; |
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140 | else if (vel2 == ERR_VEL) |
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141 | return vel1 << 1; |
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142 | else if (vel1 == ERR_VEL) |
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143 | return vel2 << 1; |
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144 | else
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145 | return vel1 + vel2;
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146 | } |
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147 | |||
148 | 868 | justin | /**
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149 | * Resets the distance accumulator for the specified
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150 | * encoder.
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151 | *
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152 | * @param encoder the encoder that you want to reset distance for
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153 | **/
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154 | void encoder_rst_dx(char encoder) { |
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155 | |||
156 | if(encoder==LEFT) left_dx = 0; |
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157 | else if(encoder==RIGHT) right_dx = 0; |
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158 | } |
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159 | |||
160 | /**
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161 | * @brief Returns the number of encoder reads that have occurred.
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162 | *
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163 | * @return The time count.
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164 | */
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165 | int encoder_get_tc(void) { |
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166 | return timecount;
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167 | } |
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168 | |||
169 | /**
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170 | * @brief Resets the encoder read counter.
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171 | */
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172 | void encoder_rst_tc(void) { |
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173 | timecount = 0;
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174 | } |
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175 | |||
176 | /**
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177 | * @brief Waits until n encoder reads have occurred.
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178 | * Counter is reset on functions exit.
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179 | *
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180 | * @param n
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181 | */
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182 | void encoder_wait(int n){ |
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183 | while(data_ready<n);
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184 | data_ready=0;
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185 | } |
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186 | |||
187 | |||
188 | //Full reads occur every 40 microseconds. This function should be called
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189 | //every 8 microseconds.
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190 | void encoder_recv(char data){ |
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191 | short int dx; |
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192 | |||
193 | //Parse the encoder data, comes in over 5 bytes 16 bits per encoder,
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194 | // second is offset by 1 bit.
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195 | switch(encoder_buf_index){
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196 | case 0: |
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197 | right_data_buf |= ((short)data)<<8 & 0xff00; |
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198 | break;
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199 | case 1: |
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200 | right_data_buf |= ((short)data) & 0xff; |
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201 | break;
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202 | case 2: |
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203 | left_data_buf |= (((short)data) << 9) & (0x7F << 9); |
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204 | break;
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205 | case 3: |
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206 | left_data_buf |= (((short)data) << 1) & (0xFF<<1); |
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207 | break;
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208 | case 4: left_data_buf |= (((short)data)>>7) & 0x1; |
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209 | } |
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210 | |||
211 | encoder_buf_index = (encoder_buf_index + 1) % 5; |
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212 | |||
213 | if(encoder_buf_index==0) { |
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214 | |||
215 | /*Error handling for the left encoder*/
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216 | if(!(left_data_buf & OCF))
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217 | left_data = ENCODER_DATA_NOT_READY; |
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218 | if(left_data_buf & (COF | LIN))
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219 | left_data = ENCODER_MISALIGNED; |
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220 | else if((left_data_buf & MagINCn) && (left_data_buf & MagDECn)) |
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221 | left_data = ENCODER_MAGNET_FAILURE; |
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222 | else left_data = (left_data_buf>>5) & 1023; |
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223 | |||
224 | /*Error handling for the right encoder*/
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225 | if(!(right_data_buf & OCF))
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226 | right_data = ENCODER_DATA_NOT_READY; |
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227 | if(right_data_buf & (COF | LIN))
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228 | right_data = ENCODER_MISALIGNED; |
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229 | else if ((right_data_buf & MagINCn) && (right_data_buf & MagDECn)) |
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230 | right_data = ENCODER_MAGNET_FAILURE; |
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231 | else right_data = (right_data_buf>>5) & 1023; |
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232 | |||
233 | left_data_buf = 0;
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234 | right_data_buf = 0;
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235 | |||
236 | /*Note: Above 1023 is invalid data*/
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237 | if(!(left_data > 1023)) { |
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238 | 870 | justin | //Reverse the left wheel since encoders are necessarily mounted backwards.
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239 | left_data = 1023 - left_data;
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240 | 868 | justin | left_data_array_put(left_data); |
241 | |||
242 | //Adjust left accumulator
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243 | dx = left_data - left_data_array_prev(); |
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244 | |||
245 | if(left_data_array_prev()==0) dx=0; |
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246 | |||
247 | if(dx > 512) left_dx += dx - 1023; //Underflow |
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248 | else if(dx < -512) left_dx += dx + 1023; //Overflow |
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249 | else left_dx += dx;
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250 | } |
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251 | |||
252 | /*Above 1023 is invalid data*/
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253 | if(!(right_data > 1023)) { |
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254 | right_data_array_put(right_data); |
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255 | |||
256 | //Adjust right accumulator
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257 | dx = right_data - right_data_array_prev(); |
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258 | |||
259 | if(right_data_array_prev()==0) dx=0; |
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260 | |||
261 | if(dx > 512) right_dx += dx - 1023; //underflow |
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262 | else if(dx < -512) right_dx += dx + 1023; //overflow |
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263 | else right_dx += dx;
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264 | } |
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265 | } |
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266 | |||
267 | //Increment timecount accumulator
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268 | timecount++; |
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269 | } |
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270 | |||
271 | |||
272 | //Helper Functions
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273 | inline void left_data_array_put(unsigned short int value) { |
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274 | if(left_data_idx == BUFFER_SIZE-1) |
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275 | left_data_idx = 0;
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276 | else
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277 | left_data_idx++; |
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278 | left_data_array[left_data_idx] = value; |
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279 | } |
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280 | |||
281 | inline unsigned int left_data_array_top(void) { |
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282 | return left_data_array[left_data_idx];
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283 | } |
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284 | |||
285 | inline unsigned int left_data_array_prev(void) { |
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286 | if(left_data_idx == 0) |
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287 | return left_data_array[BUFFER_SIZE-1]; |
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288 | else
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289 | return left_data_array[left_data_idx - 1]; |
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290 | } |
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291 | |||
292 | inline unsigned int left_data_array_bottom(void) { |
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293 | if(left_data_idx == BUFFER_SIZE-1) |
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294 | return left_data_array[0]; |
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295 | else
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296 | return left_data_array[left_data_idx + 1]; |
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297 | } |
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298 | |||
299 | inline void right_data_array_put(unsigned short int value) { |
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300 | if(right_data_idx == BUFFER_SIZE-1) |
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301 | right_data_idx = 0;
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302 | else
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303 | right_data_idx++; |
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304 | right_data_array[right_data_idx] = value; |
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305 | } |
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306 | |||
307 | inline unsigned int right_data_array_top(void) { |
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308 | return right_data_array[right_data_idx];
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309 | } |
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310 | |||
311 | inline unsigned int right_data_array_prev(void) { |
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312 | if(right_data_idx == 0) |
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313 | return right_data_array[BUFFER_SIZE-1]; |
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314 | else
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315 | return right_data_array[right_data_idx - 1]; |
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316 | } |
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317 | |||
318 | inline unsigned int right_data_array_bottom(void) { |
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319 | if(right_data_idx == BUFFER_SIZE-1) |
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320 | return right_data_array[0]; |
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321 | else
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322 | return right_data_array[right_data_idx + 1]; |
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323 | } |
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324 | |||
325 | 1418 | chihsiuh | /* Helper functions for encoder_get_v */
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326 | int left_data_at(int index) { |
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327 | int tmp_idx = left_data_idx - index;
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328 | if (tmp_idx < 0) |
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329 | tmp_idx += BUFFER_SIZE; |
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330 | return left_data_array[tmp_idx];
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331 | } |
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332 | |||
333 | int right_data_at(int index) { |
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334 | int tmp_idx = right_data_idx - index;
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335 | if (tmp_idx < 0) |
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336 | tmp_idx += BUFFER_SIZE; |
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337 | return right_data_array[tmp_idx];
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338 | } |
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339 | |||
340 | int get_dx(char encoder, int index) { |
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341 | int dx, ctr;
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342 | ctr = 0;
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343 | dx = 1024;
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344 | do {
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345 | if (encoder == LEFT)
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346 | dx = left_data_at(index+ctr) - left_data_at(index+ctr+38);
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347 | else
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348 | dx = right_data_at(index+ctr) - right_data_at(index+ctr+38);
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349 | ctr++; |
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350 | } while ((dx > 30 || dx < -30) && ctr < 3); |
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351 | if (dx > 30 || dx < -30) |
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352 | return ERR_VEL;
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353 | return dx;
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354 | } |