root / branches / encoders / code / projects / colonet / utilities / manual_control / manualControlRobot / rangefinder.c @ 1390
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1 | 13 | emarinel | /*
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2 | Authors: James Kong and Greg Tress
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3 | |||
4 | Last Modified: 4/30/06 by James
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5 | -Started log_distance conversion function !!!NOT COMPLETE!!!
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6 | -Cleaning up comments
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7 | |||
8 | -----------------
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9 | rangefinder.c
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10 | Using Sharp GP2D02 IR Rangefinder
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11 | |||
12 | Vin is the input to the rangefinder, designated RANGE_CTRL.
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13 | Vout is the output from the rangefinder, designated RANGE_IN# where # is the rangefinder you are reading from
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14 | |||
15 | Expected Initial Conditions:
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16 | Vin is high and Vout should read high.
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17 | |||
18 | Usage:
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19 | 1.) Set Vin low. Vout should read low.
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20 | 2.) Wait for high on Vout.
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21 | 3.) Begin clocking Vin and reading 8 bits from Vout (MSB first).
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22 | 4.) Set Vin high for 2ms or more to turn off rangefinder
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23 | |||
24 | */
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25 | |||
26 | #include "firefly+_lib.h" |
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27 | #include "rangefinder.h" |
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28 | |||
29 | /*
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30 | read_distance returns the 8-bit reading from the rangefinder
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31 | parameters:
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32 | range_id - dio pin set as the rangefinder Vout [i.e. RANGE_IN0]
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33 | |||
34 | NOTE:
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35 | The Sharp GD2D02 returns values on a decreasing logrithmic scale.
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36 | So higher values correspond to closer distances. Use linearize_distance to convert to normal centimeter scale.
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37 | Also, when reading distances closer than 8cm, the Sharp GD2D02 will return lower values than the values at 8cm.
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38 | At this point, we are only reading from one rangefinder [RANGE_IN0].
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39 | */
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40 | |||
41 | int read_distance (int range_id) { |
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42 | #ifndef FFPP
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43 | int bitcount;
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44 | int current = 0; |
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45 | digital_output(RANGE_CTRL, 0); //set Vin Low |
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46 | while(digital_input(range_id) == 0); //waits until Vout reads high |
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47 | digital_output(RANGE_CTRL, 1); //first Vin clock high transition |
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48 | |||
49 | for(bitcount = 8; bitcount != 0; bitcount--){ |
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50 | digital_output(RANGE_CTRL, 0); //Vin clock low transition |
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51 | //clock delay (unnecessary)
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52 | current = current << 1; //shifts current 8-bit value left |
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53 | current |= digital_input(range_id); //LSB set to Vout value
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54 | digital_output(RANGE_CTRL, 1); //Vin clock high transition |
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55 | //clock delay (unnecessary)
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56 | } //repeats until all 8 bits are stored
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57 | return current;
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58 | #else
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59 | enable_IR(); |
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60 | _delay_ms(5); ///////Figure out what this should be!!!!!! Maybe if not enabled already? |
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61 | return read_IR_val(range_id);
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62 | #endif
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63 | } |
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64 | |||
65 | /*
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66 | linearize_distance converts an 8-bit rangefinder reading to a centimeter measurement (truncated to an integer)
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67 | parameters:
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68 | reading - 8-bit rangefinder reading
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69 | |||
70 | OFFSET, GAIN, and THRESHOLD are experimentally determined constants
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71 | The conversion is a piecewise defined function with a continuity fix at reading = THRESHOLD3
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72 | |||
73 | NOTE:
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74 | This function is ugly, but it gets the job done without spending a huge amount processing.
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75 | Ideally, you want to compare with the read_distance value directly.
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76 | */
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77 | |||
78 | int linearize_distance (int reading) { |
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79 | #ifndef FFPP
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80 | int temp = reading;
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81 | if(reading > THRESHOLD1){
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82 | temp = temp - OFFSET1; |
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83 | return GAIN1 / temp;
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84 | }else if(reading > THRESHOLD2){ |
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85 | temp = temp - OFFSET2; |
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86 | return GAIN2 / temp + 1; |
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87 | }else if(reading > THRESHOLD3){ |
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88 | temp = temp - OFFSET2; |
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89 | return GAIN2 / temp;
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90 | }else if(reading == THRESHOLD3){ |
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91 | return CONTINUITY_FIX;
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92 | }else if(reading > THRESHOLD4){ |
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93 | temp = temp - OFFSET3; |
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94 | return GAIN3 / temp;
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95 | }else{
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96 | return MAX_DIST;
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97 | } |
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98 | #else
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99 | return convert_IR_distance(reading);
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100 | #endif
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101 | } |
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102 | |||
103 | /*
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104 | log_distance converts a centimeter value to a rangefinder comparable value
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105 | parameters:
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106 | distance - centimeter measurement
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107 | |||
108 | NOTE:
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109 | This is still incomplete, do not use it.
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110 | */
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111 | int log_distance(int distance) { |
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112 | #ifndef FFPP
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113 | if(distance >= MAX_DIST){
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114 | return THRESHOLD4;
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115 | } |
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116 | if(distance <= MIN_DIST){
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117 | return 255; |
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118 | } |
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119 | |||
120 | switch(distance){ //Incomplete need to fill out table |
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121 | case 60: |
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122 | return 56; |
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123 | case 59: |
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124 | return 89; |
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125 | } |
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126 | #endif
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127 | return 0; |
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128 | } |
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129 | |||
130 | |||
131 | #ifdef FFPP
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132 | |||
133 | static int IR_dist_conversion[114] = { |
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134 | 800,791,751,714,681,651,623,597,574,552,531,512,494,478,462,447 |
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135 | ,434,421,408,397,386,375,365,356,347,338,330,322,315,307,301,294 |
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136 | ,288,282,276,270,265,260,255,250,245,241,237,232,228,224,221,217 |
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137 | ,213,210,207,203,200,197,194,191,189,186,183,181,178,176,173,171 |
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138 | ,169,166,164,162,160,158,156,154,152,151,149,147,145,144,142,140 |
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139 | ,139,137,136,134,133,131,130,129,127,126,125,124,122,121,120,119 |
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140 | ,118,117,115,114,113,112,111,110,109,108,107,106,105,105,104,103 |
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141 | ,102,101 |
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142 | }; |
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143 | |||
144 | void enable_IR()
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145 | { |
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146 | // active low, so set enable to low to turn on IR
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147 | PORTC &= ~(_BV(IR_ENABLE)); |
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148 | DDRC |= _BV(IR_ENABLE); |
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149 | } |
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150 | |||
151 | void disable_IR()
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152 | { |
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153 | // active low, so set line high and turn to input for good measure (line has pull-up)
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154 | PORTC |= _BV(IR_ENABLE); |
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155 | DDRC &= ~(_BV(IR_ENABLE)); |
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156 | } |
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157 | |||
158 | int read_IR_val(int which) |
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159 | { |
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160 | return analog8(IR_READ + which);
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161 | } |
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162 | |||
163 | int convert_IR_distance(int value) |
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164 | { |
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165 | if(value < MIN_IR_ADC8)
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166 | { |
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167 | return -1; |
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168 | } |
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169 | else if(value > MAX_IR_ADC8) |
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170 | { |
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171 | return -1; |
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172 | } |
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173 | else
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174 | { |
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175 | return IR_dist_conversion[value - MIN_IR_ADC8];
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176 | } |
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177 | } |
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178 | |||
179 | int get_IR_distance(int which) |
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180 | { |
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181 | return convert_IR_distance(read_IR_val(which));
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182 | } |
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183 | #endif |