Pololu QTR Sensor Library, based on the QTR Arduino Library
Dependents: Nucleo_QTR ZumoReflectanceSensorArray speed_robot
Diff: QTRSensors.cpp
- Revision:
- 0:d54bb6a949bf
- Child:
- 1:a664ab7aba8d
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/QTRSensors.cpp Tue Aug 25 02:44:57 2015 +0000 @@ -0,0 +1,657 @@ +/* + QTRSensors.cpp - Arduino library for using Pololu QTR reflectance + sensors and reflectance sensor arrays: QTR-1A, QTR-8A, QTR-1RC, and + QTR-8RC. The object used will determine the type of the sensor (either + QTR-xA or QTR-xRC). Then simply specify in the constructor which + Arduino I/O pins are connected to a QTR sensor, and the read() method + will obtain reflectance measurements for those sensors. Smaller sensor + values correspond to higher reflectance (e.g. white) while larger + sensor values correspond to lower reflectance (e.g. black or a void). + + * QTRSensorsRC should be used for QTR-1RC and QTR-8RC sensors. + * QTRSensorsAnalog should be used for QTR-1A and QTR-8A sensors. +*/ + +/* + * Written by Ben Schmidel et al., October 4, 2010. + * Copyright (c) 2008-2012 Pololu Corporation. For more information, see + * + * http://www.pololu.com + * http://forum.pololu.com + * http://www.pololu.com/docs/0J19 + * + * You may freely modify and share this code, as long as you keep this + * notice intact (including the two links above). Licensed under the + * Creative Commons BY-SA 3.0 license: + * + * http://creativecommons.org/licenses/by-sa/3.0/ + * + * Disclaimer: To the extent permitted by law, Pololu provides this work + * without any warranty. It might be defective, in which case you agree + * to be responsible for all resulting costs and damages. + * + * Modified by Matthew Phillipps, August 24, 2015 + * Adapted to mbed platform (especially STM Nucleo boards) + * Some changes to memory management + */ + +#include <stdlib.h> +#include "QTRSensors.h" +#include "mbed.h" + + +Timer timer; + + +// Base class data member initialization (called by derived class init()) +void QTRSensors::init(PinName *pins, unsigned char numSensors, + PinName emitterPin, bool analog = false) +{ + calibratedMinimumOn=0; + calibratedMaximumOn=0; + calibratedMinimumOff=0; + calibratedMaximumOff=0; + + if (numSensors > QTR_MAX_SENSORS) + _numSensors = QTR_MAX_SENSORS; + else + _numSensors = numSensors; + + + if (_pins == 0) + { + _pins = (PinName *)malloc(sizeof(PinName)*_numSensors); + if (_pins == 0) + return; + } + unsigned char i; + + // Allocate the arrays + if(calibratedMaximumOn == 0) + { + calibratedMaximumOn = (unsigned int*)malloc(sizeof(unsigned int)*_numSensors); + + // If the malloc failed, don't continue. + if(calibratedMaximumOn == 0) + return; + + // Initialize the max and min calibrated values to values that + // will cause the first reading to update them. + + for(i=0;i<_numSensors;i++) + calibratedMaximumOn[i] = 0; + } + if(calibratedMaximumOff == 0) + { + calibratedMaximumOff = (unsigned int*)malloc(sizeof(unsigned int)*_numSensors); + + // If the malloc failed, don't continue. + if(calibratedMaximumOff == 0) + return; + + // Initialize the max and min calibrated values to values that + // will cause the first reading to update them. + + for(i=0;i<_numSensors;i++) + calibratedMaximumOff[i] = 0; + } + if(calibratedMinimumOn == 0) + { + calibratedMinimumOn = (unsigned int*)malloc(sizeof(unsigned int)*_numSensors); + + // If the malloc failed, don't continue. + if(calibratedMinimumOn == 0) + return; + + for(i=0;i<_numSensors;i++) + calibratedMinimumOn[i] = _maxValue; + } + if(calibratedMinimumOff == 0) + { + calibratedMinimumOff = (unsigned int*)malloc(sizeof(unsigned int)*_numSensors); + + // If the malloc failed, don't continue. + if(calibratedMinimumOff == 0) + return; + + for(i=0;i<_numSensors;i++) + calibratedMinimumOff[i] = _maxValue; + } + + + + for (i = 0; i < _numSensors; i++) + { + _pins[i] = pins[i]; + } + + _emitterPin = emitterPin; + _emitter = new DigitalOut(emitterPin); + + _analog = analog; + if (_analog) { + _qtrAIPins.reserve(_numSensors); + } else { + _qtrPins.reserve(_numSensors); + } + for (i = 0; i < _numSensors; i++) + { + if (_analog) { + _qtrAIPins.push_back(new AnalogIn(pins[i])); + } else { + _qtrPins.push_back(new DigitalInOut(pins[i])); + } + } + +} + + +// Reads the sensor values into an array. There *MUST* be space +// for as many values as there were sensors specified in the constructor. +// Example usage: +// unsigned int sensor_values[8]; +// sensors.read(sensor_values); +// The values returned are a measure of the reflectance in abstract units, +// with higher values corresponding to lower reflectance (e.g. a black +// surface or a void). +void QTRSensors::read(unsigned int *sensor_values, unsigned char readMode) +{ + unsigned int off_values[QTR_MAX_SENSORS]; + unsigned char i; + + + if(readMode == QTR_EMITTERS_ON || readMode == QTR_EMITTERS_ON_AND_OFF) + { + emittersOn(); } + else + { + emittersOff(); + } + + + readPrivate(sensor_values); + + emittersOff(); + + if(readMode == QTR_EMITTERS_ON_AND_OFF) + { + readPrivate(off_values); + + for(i=0;i<_numSensors;i++) + { + sensor_values[i] += _maxValue - off_values[i]; + } + } +} + + +// Turn the IR LEDs off and on. This is mainly for use by the +// read method, and calling these functions before or +// after the reading the sensors will have no effect on the +// readings, but you may wish to use these for testing purposes. +void QTRSensors::emittersOff() +{ + if (_emitterPin == QTR_NO_EMITTER_PIN) + return; +// pinMode(_emitterPin, OUTPUT); +// digitalWrite(_emitterPin, LOW); + _emitter->write(LOW); // 0 is low +// delayMicroseconds(200); + wait_ms(20); //200 was too long + +} + +void QTRSensors::emittersOn() +{ + if (_emitterPin == QTR_NO_EMITTER_PIN) + return; + + //pinMode(_emitterPin, OUTPUT); + //digitalWrite(_emitterPin, HIGH); + _emitter->write(HIGH); + //delayMicroseconds(200); + wait_ms(20); // 200 was too long +} + +// Resets the calibration. +void QTRSensors::resetCalibration() +{ + unsigned char i; + for(i=0;i<_numSensors;i++) + { + if(calibratedMinimumOn) + calibratedMinimumOn[i] = _maxValue; + if(calibratedMinimumOff) + calibratedMinimumOff[i] = _maxValue; + if(calibratedMaximumOn) + calibratedMaximumOn[i] = 0; + if(calibratedMaximumOff) + calibratedMaximumOff[i] = 0; + } +} + +// Reads the sensors 10 times and uses the results for +// calibration. The sensor values are not returned; instead, the +// maximum and minimum values found over time are stored internally +// and used for the readCalibrated() method. +void QTRSensors::calibrate(unsigned char readMode) +{ + if(readMode == QTR_EMITTERS_ON_AND_OFF || readMode == QTR_EMITTERS_ON) + { + calibrateOnOrOff(&calibratedMinimumOn, + &calibratedMaximumOn, + QTR_EMITTERS_ON); + } + + + if(readMode == QTR_EMITTERS_ON_AND_OFF || readMode == QTR_EMITTERS_OFF) + { + calibrateOnOrOff(&calibratedMinimumOff, + &calibratedMaximumOff, + QTR_EMITTERS_OFF); + } +} + +void QTRSensors::calibrateOnOrOff(unsigned int **calibratedMinimum, + unsigned int **calibratedMaximum, + unsigned char readMode) +{ + int i; + unsigned int sensor_values[16]; + unsigned int max_sensor_values[16]; + unsigned int min_sensor_values[16]; + for(i=0;i<_numSensors;i++) { + sensor_values[i] = 0; + max_sensor_values[i] = 0; + min_sensor_values[i] = _maxValue; + } + + int j; + for(j=0;j<10;j++) + { + read(sensor_values,readMode); + for(i=0;i<_numSensors;i++) + { + // set the max we found THIS time + if(j == 0 || max_sensor_values[i] < sensor_values[i]) + max_sensor_values[i] = sensor_values[i]; + + // set the min we found THIS time + if(j == 0 || min_sensor_values[i] > sensor_values[i]) + min_sensor_values[i] = sensor_values[i]; + } + } + + // record the min and max calibration values + for(i=0;i<_numSensors;i++) + { + if(min_sensor_values[i] > (*calibratedMaximum)[i]) // this was min_sensor_values[i] > (*calibratedMaximum)[i] + (*calibratedMaximum)[i] = min_sensor_values[i]; + if(max_sensor_values[i] < (*calibratedMinimum)[i]) + (*calibratedMinimum)[i] = max_sensor_values[i]; + } + +} + + +// Returns values calibrated to a value between 0 and 1000, where +// 0 corresponds to the minimum value read by calibrate() and 1000 +// corresponds to the maximum value. Calibration values are +// stored separately for each sensor, so that differences in the +// sensors are accounted for automatically. +void QTRSensors::readCalibrated(unsigned int *sensor_values, unsigned char readMode) +{ + int i; + + // if not calibrated, do nothing + if(readMode == QTR_EMITTERS_ON_AND_OFF || readMode == QTR_EMITTERS_OFF) + if(!calibratedMinimumOff || !calibratedMaximumOff) + return; + if(readMode == QTR_EMITTERS_ON_AND_OFF || readMode == QTR_EMITTERS_ON) + if(!calibratedMinimumOn || !calibratedMaximumOn) + return; + + // read the needed values + read(sensor_values,readMode); + + for(i=0;i<_numSensors;i++) + { + unsigned int calmin,calmax; + unsigned int denominator; + + // find the correct calibration + if(readMode == QTR_EMITTERS_ON) + { + calmax = calibratedMaximumOn[i]; + calmin = calibratedMinimumOn[i]; + } + else if(readMode == QTR_EMITTERS_OFF) + { + calmax = calibratedMaximumOff[i]; + calmin = calibratedMinimumOff[i]; + } + else // QTR_EMITTERS_ON_AND_OFF + { + + if(calibratedMinimumOff[i] < calibratedMinimumOn[i]) // no meaningful signal + calmin = _maxValue; + else + calmin = calibratedMinimumOn[i] + _maxValue - calibratedMinimumOff[i]; // this won't go past _maxValue + + if(calibratedMaximumOff[i] < calibratedMaximumOn[i]) // no meaningful signal + calmax = _maxValue; + else + calmax = calibratedMaximumOn[i] + _maxValue - calibratedMaximumOff[i]; // this won't go past _maxValue + } + + denominator = calmax - calmin; + + signed int x = 0; + if(denominator != 0) + x = (((signed long)sensor_values[i]) - calmin) + * 1000 / denominator; + if(x < 0) + x = 0; + else if(x > 1000) + x = 1000; + sensor_values[i] = x; + } + +} + + +// Operates the same as read calibrated, but also returns an +// estimated position of the robot with respect to a line. The +// estimate is made using a weighted average of the sensor indices +// multiplied by 1000, so that a return value of 0 indicates that +// the line is directly below sensor 0, a return value of 1000 +// indicates that the line is directly below sensor 1, 2000 +// indicates that it's below sensor 2000, etc. Intermediate +// values indicate that the line is between two sensors. The +// formula is: +// +// 0*value0 + 1000*value1 + 2000*value2 + ... +// -------------------------------------------- +// value0 + value1 + value2 + ... +// +// By default, this function assumes a dark line (high values) +// surrounded by white (low values). If your line is light on +// black, set the optional second argument white_line to true. In +// this case, each sensor value will be replaced by (1000-value) +// before the averaging. +int QTRSensors::readLine(unsigned int *sensor_values, + unsigned char readMode, unsigned char white_line) +{ + unsigned char i, on_line = 0; + unsigned long avg; // this is for the weighted total, which is long + // before division + unsigned int sum; // this is for the denominator which is <= 64000 + static int last_value=0; // assume initially that the line is left. + + readCalibrated(sensor_values, readMode); + + avg = 0; + sum = 0; + + for(i=0;i<_numSensors;i++) { + int value = sensor_values[i]; + if(white_line) + value = 1000-value; + + // keep track of whether we see the line at all + if(value > 200) { + on_line = 1; + } + + // only average in values that are above a noise threshold + if(value > 50) { + avg += (long)(value) * (i * 1000); + sum += value; + } + } + + if(!on_line) + { + // If it last read to the left of center, return 0. + if(last_value < (_numSensors-1)*1000/2) + return 0; + + // If it last read to the right of center, return the max. + else + return (_numSensors-1)*1000; + + } + + last_value = avg/sum; + + return last_value; +} + + + +// Derived RC class constructors +QTRSensorsRC::QTRSensorsRC() +{ + calibratedMinimumOn = 0; + calibratedMaximumOn = 0; + calibratedMinimumOff = 0; + calibratedMaximumOff = 0; + _pins = 0; +} + +QTRSensorsRC::QTRSensorsRC(PinName* pins, + unsigned char numSensors, unsigned int timeout, PinName emitterPin) +{ + calibratedMinimumOn = 0; + calibratedMaximumOn = 0; + calibratedMinimumOff = 0; + calibratedMaximumOff = 0; + _pins = 0; + + init(pins, numSensors, timeout, emitterPin); +} + + +// The array 'pins' contains the Arduino pin number for each sensor. + +// 'numSensors' specifies the length of the 'pins' array (i.e. the +// number of QTR-RC sensors you are using). numSensors must be +// no greater than 16. + +// 'timeout' specifies the length of time in microseconds beyond +// which you consider the sensor reading completely black. That is to say, +// if the pulse length for a pin exceeds 'timeout', pulse timing will stop +// and the reading for that pin will be considered full black. +// It is recommended that you set timeout to be between 1000 and +// 3000 us, depending on things like the height of your sensors and +// ambient lighting. Using timeout allows you to shorten the +// duration of a sensor-reading cycle while still maintaining +// useful analog measurements of reflectance + +// 'emitterPin' is the Arduino pin that controls the IR LEDs on the 8RC +// modules. If you are using a 1RC (i.e. if there is no emitter pin), +// or if you just want the emitters on all the time and don't want to +// use an I/O pin to control it, use a value of 255 (QTR_NO_EMITTER_PIN). +void QTRSensorsRC::init(PinName* pins, + unsigned char numSensors, + unsigned int timeout, PinName emitterPin) +{ + QTRSensors::init(pins, numSensors, emitterPin, false); + + _maxValue = timeout; +} + + +// Reads the sensor values into an array. There *MUST* be space +// for as many values as there were sensors specified in the constructor. +// Example usage: +// unsigned int sensor_values[8]; +// sensors.read(sensor_values); +// ... +// The values returned are in microseconds and range from 0 to +// timeout (as specified in the constructor). +void QTRSensorsRC::readPrivate(unsigned int *sensor_values) +{ + unsigned char i; + + if (_pins == 0) + return; + + + for(i = 0; i < _numSensors; i++) + { + sensor_values[i] = _maxValue; + + _qtrPins[i]->write(HIGH); // make sensor line an output + //pinMode(_pins[i], OUTPUT); // drive sensor line high + } + + wait_ms(10); // charge lines for 10 us + + for(i = 0; i < _numSensors; i++) + { +// important: disable internal pull-up! + _qtrPins[i]->write(LOW); + } + + timer.start(); + unsigned long startTime = timer.read_ms(); + while ((timer.read_ms() - startTime) < _maxValue) + { + unsigned int time = timer.read_ms() - startTime; + for (i = 0; i < _numSensors; i++) + { + if (_qtrPins[i]->read() == LOW && time < sensor_values[i]) + sensor_values[i] = time; + } + } + + timer.stop(); +} + + + +// Derived Analog class constructors +QTRSensorsAnalog::QTRSensorsAnalog() +{ + calibratedMinimumOn = 0; + calibratedMaximumOn = 0; + calibratedMinimumOff = 0; + calibratedMaximumOff = 0; + _pins = 0; +} + +QTRSensorsAnalog::QTRSensorsAnalog(PinName* pins, + unsigned char numSensors, + unsigned char numSamplesPerSensor, + PinName emitterPin) +{ + calibratedMinimumOn = 0; + calibratedMaximumOn = 0; + calibratedMinimumOff = 0; + calibratedMaximumOff = 0; + _pins = 0; + + // this is analog - so use analog = true as a parameter + + init(pins, numSensors, numSamplesPerSensor, emitterPin); +} + + +// the array 'pins' contains the Arduino analog pin assignment for each +// sensor. For example, if pins is {0, 1, 7}, sensor 1 is on +// Arduino analog input 0, sensor 2 is on Arduino analog input 1, +// and sensor 3 is on Arduino analog input 7. + +// 'numSensors' specifies the length of the 'analogPins' array (i.e. the +// number of QTR-A sensors you are using). numSensors must be +// no greater than 16. + +// 'numSamplesPerSensor' indicates the number of 10-bit analog samples +// to average per channel (i.e. per sensor) for each reading. The total +// number of analog-to-digital conversions performed will be equal to +// numSensors*numSamplesPerSensor. Note that it takes about 100 us to +// perform a single analog-to-digital conversion, so: +// if numSamplesPerSensor is 4 and numSensors is 6, it will take +// 4 * 6 * 100 us = ~2.5 ms to perform a full readLine(). +// Increasing this parameter increases noise suppression at the cost of +// sample rate. The recommended value is 4. + +// 'emitterPin' is the Arduino pin that controls the IR LEDs on the 8RC +// modules. If you are using a 1RC (i.e. if there is no emitter pin), +// or if you just want the emitters on all the time and don't want to +// use an I/O pin to control it, use a value of 255 (QTR_NO_EMITTER_PIN). +void QTRSensorsAnalog::init(PinName* pins, + unsigned char numSensors, + unsigned char numSamplesPerSensor, + PinName emitterPin) +{ + QTRSensors::init(pins, numSensors, emitterPin, true); + + _numSamplesPerSensor = numSamplesPerSensor; + _maxValue = 1023; // this is the maximum returned by the A/D conversion +} + + +// Reads the sensor values into an array. There *MUST* be space +// for as many values as there were sensors specified in the constructor. +// Example usage: +// unsigned int sensor_values[8]; +// sensors.read(sensor_values); +// The values returned are a measure of the reflectance in terms of a +// 10-bit ADC average with higher values corresponding to lower +// reflectance (e.g. a black surface or a void). +void QTRSensorsAnalog::readPrivate(unsigned int *sensor_values) +{ + unsigned char i, j; + + if (_pins == 0) + return; + + // reset the values + for(i = 0; i < _numSensors; i++) + sensor_values[i] = 0; + + for (j = 0; j < _numSamplesPerSensor; j++) + { + for (i = 0; i < _numSensors; i++) + { + sensor_values[i] += (unsigned int) _qtrAIPins[i]->read_u16(); // add the conversion result + } + } + + // get the rounded average of the readings for each sensor + for (i = 0; i < _numSensors; i++) + sensor_values[i] = (sensor_values[i] + (_numSamplesPerSensor >> 1)) / + _numSamplesPerSensor; +} + +// the destructor frees up allocated memory +QTRSensors::~QTRSensors() +{ + if(calibratedMinimumOff) + free(calibratedMinimumOff); + if(calibratedMinimumOn) + free(calibratedMinimumOn); + if(calibratedMaximumOff) + free(calibratedMaximumOff); + if(calibratedMaximumOn) + free(calibratedMaximumOn); + if (_pins) + free(_pins); + unsigned int i; + for (i = 0; i < _numSensors; i++) { + if (_analog) { + delete _qtrAIPins[i]; + } else { + delete _qtrPins[i]; + } + } + if (_analog) { + _qtrAIPins.clear(); + vector<AnalogIn *>().swap(_qtrAIPins); + } else { + _qtrPins.clear(); + vector<DigitalInOut *>().swap(_qtrPins); + } +}