Revision 1736
joystick demo - not working yet
rangefinder.c | ||
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/** |
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* Copyright (c) 2007 Colony Project |
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* |
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* Permission is hereby granted, free of charge, to any person |
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* obtaining a copy of this software and associated documentation |
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* files (the "Software"), to deal in the Software without |
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* restriction, including without limitation the rights to use, |
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* copy, modify, merge, publish, distribute, sublicense, and/or sell |
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* copies of the Software, and to permit persons to whom the |
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* Software is furnished to do so, subject to the following |
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* conditions: |
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* |
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* The above copyright notice and this permission notice shall be |
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* included in all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES |
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT |
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, |
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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* OTHER DEALINGS IN THE SOFTWARE. |
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**/ |
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/** |
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* @file rangefinder.c |
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* @brief Rangefinders |
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* |
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* Implementation of functions for rangefinder use. |
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* |
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* @author Colony Project, CMU Robotics Club |
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**/ |
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/* |
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Authors: James Kong and Greg Tress |
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Last Modified: 4/30/06 by James |
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-Started log_distance conversion function !!!NOT COMPLETE!!! |
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-Cleaning up comments |
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----------------- |
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rangefinder.c |
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Using Sharp GP2D02 IR Rangefinder |
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Vin is the input to the rangefinder, designated RANGE_CTRL. |
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Vout is the output from the rangefinder, designated RANGE_IN# where # is the rangefinder you are reading from |
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Expected Initial Conditions: |
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Vin is high and Vout should read high. |
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Usage: |
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1.) Set Vin low. Vout should read low. |
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2.) Wait for high on Vout. |
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3.) Begin clocking Vin and reading 8 bits from Vout (MSB first). |
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4.) Set Vin high for 2ms or more to turn off rangefinder |
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*/ |
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#include <avr/pgmspace.h> |
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#include "rangefinder.h" |
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#include "analog.h" |
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#include "dio.h" |
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/* |
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read_distance returns the 8-bit reading from the rangefinder |
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parameters: |
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range_id - dio pin set as the rangefinder Vout [i.e. RANGE_IN0] |
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NOTE: |
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The Sharp GD2D02 returns values on a decreasing logrithmic scale. |
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So higher values correspond to closer distances. Use linearize_distance to convert to normal centimeter scale. |
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Also, when reading distances closer than 8cm, the Sharp GD2D02 will return lower values than the values at 8cm. |
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At this point, we are only reading from one rangefinder [RANGE_IN0]. |
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*/ |
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// constants |
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/* Nasty IR approximation table |
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I'm using this for the heck of it. We can do whatever. |
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Note the minimum value is .4V (20), and the maximum is 2.6V (133). |
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Gives distance in mm. |
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excel formula(valid for inputs 20-133): ROUND(2353.6*(E2^(-1.1146))*10,0) |
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This is only valid for the GP2D12, with objects directly ahead and more than |
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10cm from the detector. See the datasheet for more information. |
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*/ |
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static int IR_dist_conversion[72] PROGMEM = { |
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327,315,303,291,281,271,262,253,245,238,231,224,218,212,206,200, |
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195,190,185,181,177,173,168,165,161,158,155,151,148,145,143,140, |
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137,134,132,130,127,125,123,121,119,117,115,114,111,110,108,106, |
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105,104,102,100,99,98,97,95,94,93,91,90,89,88,87,86,84,83,83,82, |
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81,80,79,78 |
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}; |
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/** |
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* @defgroup rangefinder Rangefinder |
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* @brief Functions for using the IR rangefinders |
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* |
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* Functions for using the IR rangefinders. |
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* |
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* @{ |
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**/ |
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/** |
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* Initializes the rangefinders. This must be called before |
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* range_read_distance. |
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* |
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* @see range_read_distance |
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**/ |
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void range_init(void) |
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{ |
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digital_output(_PIN_B4,0); |
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} |
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/** |
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* Reads the distance measured by one of the rangefinders. |
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* This distance is in arbitrary units. |
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* |
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* @param range_id the rangefinder to use. This should be one |
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* of the constants IR1 - IR5. |
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* |
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* @return the distance measured by the rangefinder |
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* |
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* @see range_init |
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**/ |
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int range_read_distance(int range_id) { |
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return linearize_distance(analog_get8(range_id)); |
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} |
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/** |
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* Transforms distance readings from logarithmic to linear scale. |
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* This probably isn't the function you are looking for. |
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* |
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* Note: pgm_read_word() needs additional testing |
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* |
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* @param value the 8-bit analog value from rangefinder |
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* |
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* @return linearized distance reading from rangefinder (integer in [101,800]) |
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**/ |
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int linearize_distance(int value) { |
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if(value < MIN_IR_ADC8) { |
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return -1; |
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} else if(value > MAX_IR_ADC8) { |
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return -1; |
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} else { |
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return pgm_read_word(&(IR_dist_conversion[value - MIN_IR_ADC8])); |
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} |
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} |
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/** @} **/ //end defgroup |
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