Alvaro Cassinelli / Mbed 2 deprecated laserUI

Laser Sensing Display for UI interfaces in the real world

Dependencies:   mbed

Fork of skinGames_forktest by Alvaro Cassinelli

hardwareIO/lockin.cpp@47:199042980678, 2014-04-17 (annotated)

Committer:
mbedalvaro
Date:
Thu Apr 17 08:04:14 2014 +0000
Revision:
47:199042980678
Parent:
41:74e24a0e6e50 
publishing for sharing with Ken Iwasaki

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbedalvaro 41:74e24a0e6e50 1 #include "lockin.h"
mbedalvaro 41:74e24a0e6e50 2
mbedalvaro 41:74e24a0e6e50 3 Lockin lockin=Lockin();//pre-instanciation of object lockin with inter-file scope (declared extern in .h file)
mbedalvaro 41:74e24a0e6e50 4
mbedalvaro 41:74e24a0e6e50 5
mbedalvaro 41:74e24a0e6e50 6 // NOTE: the ADC interrupt catching function is not a method of the Lockin class, hence the use of the pre-instantiated object "lockin":
mbedalvaro 41:74e24a0e6e50 7 void catchInterupt(uint32_t value){
mbedalvaro 41:74e24a0e6e50 8 lockin.buffer_pos=(lockin.buffer_pos+1)%BUFFER_SIZE;
mbedalvaro 41:74e24a0e6e50 9 lockin.buffer[lockin.buffer_pos] = (value>>4)&0xFFF; // this is 12 bit precision ADC (0 to 4095), can be stored in an "unsigned short" (two bytes)
mbedalvaro 41:74e24a0e6e50 10 }
mbedalvaro 41:74e24a0e6e50 11
mbedalvaro 41:74e24a0e6e50 12 // PWM generation is configure as double edge
mbedalvaro 41:74e24a0e6e50 13 // MR0 (Match Register 0) control the frequency
mbedalvaro 41:74e24a0e6e50 14 // 'pwm2' uses MR1 and MR2 (rising and falling edges)
mbedalvaro 41:74e24a0e6e50 15 // 'pwm4' uses MR3 and MR4 (rising and falling edges)
mbedalvaro 41:74e24a0e6e50 16 // 'pwm1' and 'pwm3' cannot be used since they share the same Match Register
mbedalvaro 41:74e24a0e6e50 17 // for the moment, all PWM pin are set as output:
mbedalvaro 41:74e24a0e6e50 18 PwmOut pwm1(p26);
mbedalvaro 41:74e24a0e6e50 19 PwmOut pwm2(LOCKIN_LASER_PIN); //USED: this is pin p25, the LOCKIN_LASER_PIN
mbedalvaro 41:74e24a0e6e50 20 PwmOut pwm3(p24);
mbedalvaro 41:74e24a0e6e50 21 PwmOut pwm4(LOCKIN_REF_PIN); //USED: this is pin p22, the LOCKIN_REF_PIN
mbedalvaro 41:74e24a0e6e50 22 PwmOut pwm5(p22);
mbedalvaro 41:74e24a0e6e50 23 PwmOut pwm6(p21);
mbedalvaro 41:74e24a0e6e50 24
mbedalvaro 41:74e24a0e6e50 25 //Lockin::Lockin(){}
mbedalvaro 41:74e24a0e6e50 26
mbedalvaro 41:74e24a0e6e50 27 void Lockin::init(){
mbedalvaro 41:74e24a0e6e50 28
mbedalvaro 41:74e24a0e6e50 29 //configure PWM for the laser and the Lockin
mbedalvaro 41:74e24a0e6e50 30 refFreq = 147;
mbedalvaro 41:74e24a0e6e50 31 offsetRef = 40;
mbedalvaro 41:74e24a0e6e50 32 halfRefFreq = refFreq / 2;
mbedalvaro 41:74e24a0e6e50 33
mbedalvaro 41:74e24a0e6e50 34 refFrequency = 653; //init the lock-in frequency at 653 kHz
mbedalvaro 41:74e24a0e6e50 35 phaseShiftLaser = 0.546; //offset of 54% for the laser signal
mbedalvaro 41:74e24a0e6e50 36 phaseShiftLockin = 0; //no offset for the lock-in reference
mbedalvaro 41:74e24a0e6e50 37 initPWM();
mbedalvaro 41:74e24a0e6e50 38
mbedalvaro 41:74e24a0e6e50 39 //configure ADC:
mbedalvaro 41:74e24a0e6e50 40 clearBuffer();
mbedalvaro 41:74e24a0e6e50 41
mbedalvaro 41:74e24a0e6e50 42 // SET ADC IN BURST MODE:
mbedalvaro 41:74e24a0e6e50 43 lockin.setADC_forLockin(1);
mbedalvaro 41:74e24a0e6e50 44 }
mbedalvaro 41:74e24a0e6e50 45
mbedalvaro 41:74e24a0e6e50 46 void Lockin::setADC_forLockin(int mode) {
mbedalvaro 41:74e24a0e6e50 47 if (mode>0) {
mbedalvaro 41:74e24a0e6e50 48 adc.startmode(0,0);
mbedalvaro 41:74e24a0e6e50 49 adc.burst(1);
mbedalvaro 41:74e24a0e6e50 50 adc.setup(LOCKIN_ADC_PIN, 1);
mbedalvaro 41:74e24a0e6e50 51 adc.select(LOCKIN_ADC_PIN);
mbedalvaro 41:74e24a0e6e50 52 adc.interrupt_state(LOCKIN_ADC_PIN, 1);
mbedalvaro 41:74e24a0e6e50 53 adc.append(LOCKIN_ADC_PIN, catchInterupt);
mbedalvaro 41:74e24a0e6e50 54 } else {
mbedalvaro 41:74e24a0e6e50 55 //adc.startmode(0,0);
mbedalvaro 41:74e24a0e6e50 56 adc.burst(0);
mbedalvaro 41:74e24a0e6e50 57 adc.setup(LOCKIN_ADC_PIN, 0);
mbedalvaro 41:74e24a0e6e50 58 //adc.select(LOCKIN_ADC_PIN);
mbedalvaro 41:74e24a0e6e50 59 adc.interrupt_state(LOCKIN_ADC_PIN, 0);
mbedalvaro 41:74e24a0e6e50 60 //adc.append(LOCKIN_ADC_PIN, catchInterupt);
mbedalvaro 41:74e24a0e6e50 61 }
mbedalvaro 41:74e24a0e6e50 62 }
mbedalvaro 41:74e24a0e6e50 63
mbedalvaro 41:74e24a0e6e50 64 void Lockin::initPWM(){
mbedalvaro 41:74e24a0e6e50 65
mbedalvaro 41:74e24a0e6e50 66 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency; // half shared periof
mbedalvaro 41:74e24a0e6e50 67 _currentMR[0] = int(1.0 * MBEDFREQUENCY / refFrequency); //save the current value of MR0 (shared periof) //147
mbedalvaro 41:74e24a0e6e50 68 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1 //40
mbedalvaro 41:74e24a0e6e50 69 _currentMR[2] = int(_currentMR[1] + halfPeriod); //save the current value of MR2 //40+73
mbedalvaro 41:74e24a0e6e50 70 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1 //0
mbedalvaro 41:74e24a0e6e50 71 _currentMR[4] = int(_currentMR[3] + halfPeriod); //save the current value of MR2 //73
mbedalvaro 41:74e24a0e6e50 72
mbedalvaro 41:74e24a0e6e50 73
mbedalvaro 41:74e24a0e6e50 74 // set PWM:
mbedalvaro 41:74e24a0e6e50 75 LPC_PWM1->TCR = (1 << 1); // Reset counter, disable PWM
mbedalvaro 41:74e24a0e6e50 76 LPC_SC->PCLKSEL0 &= ~(0x3 << 12);
mbedalvaro 41:74e24a0e6e50 77 LPC_SC->PCLKSEL0 |= (1 << 12); // Set peripheral clock divider to /1, i.e. system clock
mbedalvaro 41:74e24a0e6e50 78
mbedalvaro 41:74e24a0e6e50 79 LPC_PWM1->PCR |= 0x0014; // Double edge PWM for PWM2,4
mbedalvaro 41:74e24a0e6e50 80
mbedalvaro 41:74e24a0e6e50 81 LPC_PWM1->MR0 = _currentMR[0]; // Match Register 0 is shared period counter for all PWM1
mbedalvaro 41:74e24a0e6e50 82
mbedalvaro 41:74e24a0e6e50 83 LPC_PWM1->MR1 = _currentMR[1]; // Match Register 1 is laser rising edge counter
mbedalvaro 41:74e24a0e6e50 84 LPC_PWM1->MR2 = _currentMR[2]; // Match Register 2 is laser falling edge counter
mbedalvaro 41:74e24a0e6e50 85 LPC_PWM1->MR3 = _currentMR[3]; // Match Register 3 is lock-in rising edge counter
mbedalvaro 41:74e24a0e6e50 86 LPC_PWM1->MR4 = _currentMR[4]; // Match Register 4 is lock-in falling edge counter
mbedalvaro 41:74e24a0e6e50 87
mbedalvaro 41:74e24a0e6e50 88 LPC_PWM1->LER |= 1; // Start updating at next period start
mbedalvaro 41:74e24a0e6e50 89 LPC_PWM1->TCR = (1 << 0) || (1 << 3); // Enable counter and PWM
mbedalvaro 41:74e24a0e6e50 90 }
mbedalvaro 41:74e24a0e6e50 91
mbedalvaro 41:74e24a0e6e50 92 //change the frequency of the PWM after initPWM()
mbedalvaro 41:74e24a0e6e50 93 void Lockin::setPWMFrequency(float freq){
mbedalvaro 41:74e24a0e6e50 94 refFrequency = freq;
mbedalvaro 41:74e24a0e6e50 95 _currentMR[0] = int(MBEDFREQUENCY / refFrequency); //save the current value of MR0
mbedalvaro 41:74e24a0e6e50 96 LPC_PWM1->MR0 = _currentMR[0]; //update PWM shared period register
mbedalvaro 41:74e24a0e6e50 97 LPC_PWM1->LER |= 1; //update PWM
mbedalvaro 41:74e24a0e6e50 98 }
mbedalvaro 41:74e24a0e6e50 99
mbedalvaro 41:74e24a0e6e50 100 //change the phase shift of the sensing laser after initPWM()
mbedalvaro 41:74e24a0e6e50 101 void Lockin::setLaserPhaseShift(float phaseShift){
mbedalvaro 41:74e24a0e6e50 102 phaseShiftLaser = phaseShift;
mbedalvaro 41:74e24a0e6e50 103 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 41:74e24a0e6e50 104 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1
mbedalvaro 41:74e24a0e6e50 105 _currentMR[2] = _currentMR[1] + halfPeriod; //save the current value of MR2
mbedalvaro 41:74e24a0e6e50 106
mbedalvaro 41:74e24a0e6e50 107 LPC_PWM1->MR1 = _currentMR[1]; //update Laser rising edge match register
mbedalvaro 41:74e24a0e6e50 108 LPC_PWM1->MR2 = _currentMR[2]; //update Laser faling edge match register
mbedalvaro 41:74e24a0e6e50 109 }
mbedalvaro 41:74e24a0e6e50 110
mbedalvaro 41:74e24a0e6e50 111 //change the phase shift of the lock-in after initPWM()
mbedalvaro 41:74e24a0e6e50 112 void Lockin::setLockinPhaseShift(float phaseShift){
mbedalvaro 41:74e24a0e6e50 113 phaseShiftLockin = phaseShift;
mbedalvaro 41:74e24a0e6e50 114 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 41:74e24a0e6e50 115 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1
mbedalvaro 41:74e24a0e6e50 116 _currentMR[4] = _currentMR[3] + halfPeriod; //save the current value of MR2
mbedalvaro 41:74e24a0e6e50 117
mbedalvaro 41:74e24a0e6e50 118 LPC_PWM1->MR3 = _currentMR[3]; //update lock-in rising edge match register
mbedalvaro 41:74e24a0e6e50 119 LPC_PWM1->MR4 = _currentMR[4]; //update lock-in faling edge match register
mbedalvaro 41:74e24a0e6e50 120 }
mbedalvaro 41:74e24a0e6e50 121
mbedalvaro 41:74e24a0e6e50 122
mbedalvaro 41:74e24a0e6e50 123 void Lockin::setLaserPower(bool power){
mbedalvaro 41:74e24a0e6e50 124 if(power){
mbedalvaro 41:74e24a0e6e50 125 LPC_PWM1->MR1 = _currentMR[1];
mbedalvaro 41:74e24a0e6e50 126 LPC_PWM1->MR2 = _currentMR[2];
mbedalvaro 41:74e24a0e6e50 127 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 41:74e24a0e6e50 128 }
mbedalvaro 41:74e24a0e6e50 129 else{
mbedalvaro 41:74e24a0e6e50 130 LPC_PWM1->MR1 = 0; //set rising edge at 0
mbedalvaro 41:74e24a0e6e50 131 LPC_PWM1->MR2 = 0; //set falling edge at 0
mbedalvaro 41:74e24a0e6e50 132 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 41:74e24a0e6e50 133 }
mbedalvaro 41:74e24a0e6e50 134 }
mbedalvaro 41:74e24a0e6e50 135
mbedalvaro 41:74e24a0e6e50 136 void Lockin::clearBuffer(){
mbedalvaro 41:74e24a0e6e50 137 for(int i=0; i<BUFFER_SIZE; i++){
mbedalvaro 41:74e24a0e6e50 138 buffer[i] = 0;
mbedalvaro 41:74e24a0e6e50 139 }
mbedalvaro 41:74e24a0e6e50 140 buffer_pos = BUFFER_SIZE;
mbedalvaro 41:74e24a0e6e50 141 }
mbedalvaro 41:74e24a0e6e50 142
mbedalvaro 41:74e24a0e6e50 143 /*
mbedalvaro 41:74e24a0e6e50 144 void Lockin::catchInterupt(uint32_t value){
mbedalvaro 41:74e24a0e6e50 145 buffer_pos++;
mbedalvaro 41:74e24a0e6e50 146 buffer_pos%=BUFFER_SIZE;
mbedalvaro 41:74e24a0e6e50 147 buffer[buffer_pos] = value;
mbedalvaro 41:74e24a0e6e50 148 }
mbedalvaro 41:74e24a0e6e50 149 */
mbedalvaro 41:74e24a0e6e50 150
mbedalvaro 41:74e24a0e6e50 151 //****** aquisition method *****//
mbedalvaro 41:74e24a0e6e50 152 unsigned short Lockin::getLastValue(){
mbedalvaro 41:74e24a0e6e50 153 return buffer[buffer_pos];
mbedalvaro 41:74e24a0e6e50 154 }
mbedalvaro 41:74e24a0e6e50 155
mbedalvaro 41:74e24a0e6e50 156 unsigned short Lockin::getSmoothValue(){
mbedalvaro 41:74e24a0e6e50 157 unsigned short smoothValue = buffer[0];
mbedalvaro 41:74e24a0e6e50 158 for(int i=1; i<BUFFER_SIZE; i++){
mbedalvaro 41:74e24a0e6e50 159 smoothValue += buffer[i];
mbedalvaro 41:74e24a0e6e50 160 }
mbedalvaro 41:74e24a0e6e50 161 smoothValue = (unsigned short)(smoothValue/BUFFER_SIZE); // note: we could have more precision (sub-12 bit), but it's not required and would imply using a float as output
mbedalvaro 41:74e24a0e6e50 162
mbedalvaro 41:74e24a0e6e50 163 return smoothValue;
mbedalvaro 41:74e24a0e6e50 164 }
mbedalvaro 41:74e24a0e6e50 165
mbedalvaro 41:74e24a0e6e50 166 unsigned short Lockin::getMedianValue(){
mbedalvaro 41:74e24a0e6e50 167 //this method applies a median filter to the buffer
mbedalvaro 41:74e24a0e6e50 168 //It reduces the salt-and-pepper noise
mbedalvaro 41:74e24a0e6e50 169 //It seems that this noise is very strong on certain mBed board, but not all...
mbedalvaro 41:74e24a0e6e50 170
mbedalvaro 41:74e24a0e6e50 171 // unsigned short orderedBuffer[BUFFER_SIZE_MEDIAN];
mbedalvaro 41:74e24a0e6e50 172
mbedalvaro 41:74e24a0e6e50 173 //sort half of the buffer:
mbedalvaro 41:74e24a0e6e50 174
mbedalvaro 41:74e24a0e6e50 175 //copy buffer
mbedalvaro 41:74e24a0e6e50 176 for(int i=0; i<BUFFER_SIZE_MEDIAN; i++){
mbedalvaro 41:74e24a0e6e50 177 orderedBuffer[i] = buffer[(buffer_pos+BUFFER_SIZE-i+DELAY_BUFFER_MEDIAN)%BUFFER_SIZE];
mbedalvaro 41:74e24a0e6e50 178 }
mbedalvaro 41:74e24a0e6e50 179
mbedalvaro 41:74e24a0e6e50 180 //order buffer
mbedalvaro 41:74e24a0e6e50 181 for(int i=0; i<BUFFER_SIZE_MEDIAN-1; i++){
mbedalvaro 41:74e24a0e6e50 182 int minPos = i;
mbedalvaro 41:74e24a0e6e50 183
mbedalvaro 41:74e24a0e6e50 184 //get min
mbedalvaro 41:74e24a0e6e50 185 for(int j=i+1; j<BUFFER_SIZE_MEDIAN; j++){
mbedalvaro 41:74e24a0e6e50 186 if(orderedBuffer[j] < orderedBuffer[minPos]) minPos = j;
mbedalvaro 41:74e24a0e6e50 187 }
mbedalvaro 41:74e24a0e6e50 188
mbedalvaro 41:74e24a0e6e50 189 //swap min to the right position
mbedalvaro 41:74e24a0e6e50 190 if(minPos != i){
mbedalvaro 41:74e24a0e6e50 191 int tmpMin = orderedBuffer[minPos];
mbedalvaro 41:74e24a0e6e50 192 orderedBuffer[minPos] = orderedBuffer[i];
mbedalvaro 41:74e24a0e6e50 193 orderedBuffer[i] = tmpMin;
mbedalvaro 41:74e24a0e6e50 194 }
mbedalvaro 41:74e24a0e6e50 195 }
mbedalvaro 41:74e24a0e6e50 196
mbedalvaro 41:74e24a0e6e50 197 return orderedBuffer[BUFFER_SIZE_MEDIAN/2];
mbedalvaro 41:74e24a0e6e50 198 }
mbedalvaro 41:74e24a0e6e50 199