root / trunk / code / projects / rangefinders / rangefinder.c @ 1475
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1 | 1455 | dshope | /**
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2 | * Copyright (c) 2007 Colony Project
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3 | *
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4 | * Permission is hereby granted, free of charge, to any person
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5 | * obtaining a copy of this software and associated documentation
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6 | * files (the "Software"), to deal in the Software without
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7 | * restriction, including without limitation the rights to use,
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8 | * copy, modify, merge, publish, distribute, sublicense, and/or sell
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9 | * copies of the Software, and to permit persons to whom the
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10 | * Software is furnished to do so, subject to the following
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11 | * conditions:
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12 | *
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13 | * The above copyright notice and this permission notice shall be
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14 | * included in all copies or substantial portions of the Software.
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15 | *
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16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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17 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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18 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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19 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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20 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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21 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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22 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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23 | * OTHER DEALINGS IN THE SOFTWARE.
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24 | **/
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25 | |||
26 | |||
27 | /**
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28 | * @file rangefinder.c
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29 | * @brief Rangefinders
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30 | *
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31 | * Implementation of functions for rangefinder use.
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32 | *
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33 | * @author Colony Project, CMU Robotics Club
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34 | **/
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35 | |||
36 | /*
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37 | Authors: James Kong and Greg Tress
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38 | |||
39 | 1475 | dshope | Last Modified: 10/30/09 by Dan Shope
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40 | 1455 | dshope | -Revised LUT to match GP2D120X Sensors (4-30cm)
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41 | -range_read_distance() now returns -1 for below lower bound, -2 for beyond upper bound
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42 | |||
43 | Modified: 4/30/06 by James
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44 | -Started log_distance conversion function !!!NOT COMPLETE!!!
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45 | -Cleaning up comments
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46 | |||
47 | -----------------
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48 | rangefinder.c
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49 | 1475 | dshope | Using Sharp GP2D02 IR Rangefinder
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50 | 1455 | dshope | |
51 | Vin is the input to the rangefinder, designated RANGE_CTRL.
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52 | Vout is the output from the rangefinder, designated RANGE_IN# where # is the rangefinder you are reading from
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53 | |||
54 | Expected Initial Conditions:
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55 | Vin is high and Vout should read high.
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56 | |||
57 | Usage:
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58 | 1.) Set Vin low. Vout should read low.
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59 | 2.) Wait for high on Vout.
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60 | 3.) Begin clocking Vin and reading 8 bits from Vout (MSB first).
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61 | 4.) Set Vin high for 2ms or more to turn off rangefinder
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62 | |||
63 | */
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64 | 1475 | dshope | #include <avr/pgmspace.h> |
65 | 1455 | dshope | |
66 | 1475 | dshope | #include "dragonfly_defs.h" |
67 | #include "analog.h" |
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68 | #include "dio.h" |
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69 | 1455 | dshope | #include "rangefinder.h" |
70 | |||
71 | 1475 | dshope | unsigned char range_initd=0; |
72 | |||
73 | 1455 | dshope | /*
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74 | read_distance returns the 8-bit reading from the rangefinder
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75 | parameters:
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76 | range_id - dio pin set as the rangefinder Vout [i.e. RANGE_IN0]
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77 | |||
78 | NOTE:
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79 | The Sharp GD2D02 returns values on a decreasing logrithmic scale.
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80 | So higher values correspond to closer distances. Use linearize_distance to convert to normal centimeter scale.
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81 | Also, when reading distances closer than 8cm, the Sharp GD2D02 will return lower values than the values at 8cm.
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82 | At this point, we are only reading from one rangefinder [RANGE_IN0].
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83 | */
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84 | |||
85 | // constants
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86 | /* Averaged over 5 robots, should give real (mm) values to +/-10 millimeters
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87 | |||
88 | Note the minimum value is .4V (20), and the maximum is 2.6V (133).
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89 | Gives distance in mm.
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90 | |||
91 | excel formula(valid for inputs 20-133): ROUND(2353.6*(E2^(-1.1146))*10,0)
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92 | |||
93 | This is only valid for the GP2D120X, with objects directly ahead and more than
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94 | 10cm from the detector. See the datasheet for more information.
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95 | */
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96 | |||
97 | 1475 | dshope | static int IR_dist_conversion[72] PROGMEM = { |
98 | 1455 | dshope | 327,315,303,291,281,271,262,253,245,238,231,224,218,212,206,200, |
99 | 195,190,185,181,177,173,168,165,161,158,155,151,148,145,143,140, |
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100 | 137,134,132,130,127,125,123,121,119,117,115,114,111,110,108,106, |
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101 | 105,104,102,100,99,98,97,95,94,93,91,90,89,88,87,86,84,83,83,82, |
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102 | 81,80,79,78 |
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103 | }; |
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104 | |||
105 | /**
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106 | * @defgroup rangefinder Rangefinder
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107 | * @brief Functions for using the IR rangefinders
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108 | *
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109 | * Functions for using the IR rangefinders.
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110 | *
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111 | * @{
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112 | **/
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113 | |||
114 | /**
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115 | * Initializes the rangefinders. This must be called before
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116 | * range_read_distance.
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117 | *
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118 | * @see range_read_distance
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119 | **/
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120 | 1475 | dshope | int range_init(void) |
121 | 1455 | dshope | { |
122 | 1475 | dshope | if(range_initd)
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123 | return ERROR_INIT_ALREADY_INITD;
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124 | |||
125 | 1455 | dshope | digital_output(_PIN_B4,0);
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126 | 1475 | dshope | |
127 | range_initd=1;
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128 | return 0; |
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129 | 1455 | dshope | } |
130 | |||
131 | /**
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132 | * Reads the distance measured by one of the rangefinders.
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133 | * This distance is in arbitrary units.
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134 | *
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135 | * @param range_id the rangefinder to use. This should be one
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136 | * of the constants IR1 - IR5.
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137 | *
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138 | 1475 | dshope | * @return the distance measured by the rangefinder, or an error code
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139 | 1455 | dshope | *
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140 | * @see range_init
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141 | **/
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142 | int range_read_distance(int range_id) { |
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143 | 1475 | dshope | if(!range_initd)
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144 | return -3; |
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145 | |||
146 | 1455 | dshope | return linearize_distance(analog8(range_id));
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147 | } |
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148 | |||
149 | /**
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150 | * Transforms distance readings from logarithmic to linear scale.
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151 | * This probably isn't the function you are looking for.
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152 | *
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153 | 1475 | dshope | * Note: pgm_read_word() needs additional testing
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154 | *
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155 | 1455 | dshope | * @param value the 8-bit analog value from rangefinder
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156 | *
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157 | * @return linearized distance reading from rangefinder (integer in [78,327])
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158 | 1475 | dshope | * @return (-2) if below MIN_IR_ADC8
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159 | * @return (-1) if beyond MAX_IR_ADC8
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160 | 1455 | dshope | **/
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161 | int linearize_distance(int value) { |
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162 | if(value < MIN_IR_ADC8) {
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163 | 1475 | dshope | return -2; |
164 | } else if(value > MAX_IR_ADC8) { |
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165 | 1455 | dshope | return -1; |
166 | } else {
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167 | 1475 | dshope | return pgm_read_word(&(IR_dist_conversion[value - MIN_IR_ADC8]));
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168 | 1455 | dshope | } |
169 | } |
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170 | |||
171 | 1475 | dshope | |
172 | 1455 | dshope | /** @} **/ //end defgroup |