72 lines
3.0 KiB
C
72 lines
3.0 KiB
C
// IRDistance.c
|
|
// Runs on any microcontroller
|
|
// Provide mid-level functions that convert raw ADC
|
|
// values from the GP2Y0A21YK0F infrared distance sensors to
|
|
// distances in mm. STUDENTS WILL NEED TO CALIBRATE THEIR OWN SENSORS
|
|
// Jonathan Valvano
|
|
// Jan 15, 2020
|
|
|
|
/* This example accompanies the book
|
|
"Embedded Systems: Introduction to Robotics,
|
|
Jonathan W. Valvano, ISBN: 9781074544300, copyright (c) 2020
|
|
For more information about my classes, my research, and my books, see
|
|
http://users.ece.utexas.edu/~valvano/
|
|
|
|
Simplified BSD License (FreeBSD License)
|
|
Copyright (c) 2020, Jonathan Valvano, All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without modification,
|
|
are permitted provided that the following conditions are met:
|
|
|
|
1. Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
2. Redistributions in binary form must reproduce the above copyright notice,
|
|
this list of conditions and the following disclaimer in the documentation
|
|
and/or other materials provided with the distribution.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
|
|
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
|
|
USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
The views and conclusions contained in the software and documentation are
|
|
those of the authors and should not be interpreted as representing official
|
|
policies, either expressed or implied, of the FreeBSD Project.
|
|
*/
|
|
|
|
|
|
|
|
#include <stdint.h>
|
|
|
|
/* Calibration data
|
|
distance measured from front of the sensor to the wall
|
|
d(cm) 1/d bL al aR bR adcSample d (0.01cm) error
|
|
10 0.100 2813 2830 2820 2830 2823.25 1006 0.06
|
|
15 0.067 1935 1976 1986 1978 1968.75 1482 -0.18
|
|
20 0.050 1520 1500 1520 1550 1522.5 1966 -0.34
|
|
30 0.033 1040 1096 1028 933 1024.25 3099 0.99
|
|
|
|
adcSample = 26813/d+159 2681300
|
|
d = 26813/(adcSample-159) -159
|
|
*/
|
|
const int32_t A[4] = { 268130,268130,268130,268130};
|
|
const int32_t B[4] = { -159,-159,-159,-159};
|
|
const int32_t C[4] = { 0,0,0,0};
|
|
const int32_t IRmax[4] = { 494,494,494,494};
|
|
// returns distance in mm
|
|
int32_t IRDistance_Convert(int32_t adcSample, uint32_t sensor){
|
|
if(adcSample < IRmax[sensor]){
|
|
return 800;
|
|
}
|
|
return A[sensor]/(adcSample + B[sensor]) + C[sensor];
|
|
}
|
|
|
|
|
|
|