Alvaro Cassinelli / Mbed 2 deprecated laserUI

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   mbed

Fork of skinGames_forktest by Alvaro Cassinelli

hardwareIO/lockin.cpp@34:1244fa3f2559, 2012-11-07 (annotated)

Committer:
mbedalvaro
Date:
Wed Nov 07 14:41:55 2012 +0000
Revision:
34:1244fa3f2559
Parent:
31:5f039cbddee8
Child:
37:fa6b1f15819f
added hardware button & potentiometer to select the thresholding mode and parameters. Problems with the ADC conversion though...

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbedalvaro 34:1244fa3f2559 1 #include "lockin.h"
mbedalvaro 34:1244fa3f2559 2
mbedalvaro 34:1244fa3f2559 3 Lockin lockin=Lockin();//pre-instanciation of object lockin with inter-file scope (declared extern in .h file)
mbedalvaro 34:1244fa3f2559 4
mbedalvaro 34:1244fa3f2559 5
mbedalvaro 34:1244fa3f2559 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 34:1244fa3f2559 7 void catchInterupt(uint32_t value){
mbedalvaro 34:1244fa3f2559 8 lockin.buffer_pos=(lockin.buffer_pos+1)%BUFFER_SIZE;
mbedalvaro 34:1244fa3f2559 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 34:1244fa3f2559 10 }
mbedalvaro 34:1244fa3f2559 11
mbedalvaro 34:1244fa3f2559 12 // PWM generation is configure as double edge
mbedalvaro 34:1244fa3f2559 13 // MR0 (Match Register 0) control the frequency
mbedalvaro 34:1244fa3f2559 14 // 'pwm2' uses MR1 and MR2 (rising and falling edges)
mbedalvaro 34:1244fa3f2559 15 // 'pwm4' uses MR3 and MR4 (rising and falling edges)
mbedalvaro 34:1244fa3f2559 16 // 'pwm1' and 'pwm3' cannot be used since they share the same Match Register
mbedalvaro 34:1244fa3f2559 17 // for the moment, all PWM pin are set as output:
mbedalvaro 34:1244fa3f2559 18 PwmOut pwm1(p26);
mbedalvaro 34:1244fa3f2559 19 PwmOut pwm2(LOCKIN_LASER_PIN); //USED: this is pin p25, the LOCKIN_LASER_PIN
mbedalvaro 34:1244fa3f2559 20 PwmOut pwm3(p24);
mbedalvaro 34:1244fa3f2559 21 PwmOut pwm4(LOCKIN_REF_PIN); //USED: this is pin p23, the LOCKIN_REF_PIN
mbedalvaro 34:1244fa3f2559 22 PwmOut pwm5(p22);
mbedalvaro 34:1244fa3f2559 23 PwmOut pwm6(p21);
mbedalvaro 34:1244fa3f2559 24
mbedalvaro 34:1244fa3f2559 25 //Lockin::Lockin(){}
mbedalvaro 34:1244fa3f2559 26
mbedalvaro 34:1244fa3f2559 27 void Lockin::init(){
mbedalvaro 34:1244fa3f2559 28
mbedalvaro 34:1244fa3f2559 29 //configure PWM for the laser and the Lockin
mbedalvaro 34:1244fa3f2559 30 refFreq = 147;
mbedalvaro 34:1244fa3f2559 31 offsetRef = 40;
mbedalvaro 34:1244fa3f2559 32 halfRefFreq = refFreq / 2;
mbedalvaro 34:1244fa3f2559 33
mbedalvaro 34:1244fa3f2559 34 refFrequency = 653; //init the lock-in frequency at 653 kHz
mbedalvaro 34:1244fa3f2559 35 phaseShiftLaser = 0.546; //offset of 54% for the laser signal
mbedalvaro 34:1244fa3f2559 36 phaseShiftLockin = 0; //no offset for the lock-in reference
mbedalvaro 34:1244fa3f2559 37 initPWM();
mbedalvaro 34:1244fa3f2559 38
mbedalvaro 34:1244fa3f2559 39 //configure ADC:
mbedalvaro 34:1244fa3f2559 40 clearBuffer();
mbedalvaro 34:1244fa3f2559 41
mbedalvaro 34:1244fa3f2559 42 // SET ADC IN BURST MODE:
mbedalvaro 34:1244fa3f2559 43 lockin.setADC_forLockin(1);
mbedalvaro 34:1244fa3f2559 44 }
mbedalvaro 34:1244fa3f2559 45
mbedalvaro 34:1244fa3f2559 46 void Lockin::setADC_forLockin(int mode) {
mbedalvaro 34:1244fa3f2559 47 if (mode>0) {
mbedalvaro 34:1244fa3f2559 48 adc.startmode(0,0);
mbedalvaro 34:1244fa3f2559 49 adc.burst(1);
mbedalvaro 34:1244fa3f2559 50 adc.setup(LOCKIN_ADC_PIN, 1);
mbedalvaro 34:1244fa3f2559 51 adc.select(LOCKIN_ADC_PIN);
mbedalvaro 34:1244fa3f2559 52 adc.interrupt_state(LOCKIN_ADC_PIN, 1);
mbedalvaro 34:1244fa3f2559 53 adc.append(LOCKIN_ADC_PIN, catchInterupt);
mbedalvaro 34:1244fa3f2559 54 } else {
mbedalvaro 34:1244fa3f2559 55 //adc.startmode(0,0);
mbedalvaro 34:1244fa3f2559 56 adc.burst(0);
mbedalvaro 34:1244fa3f2559 57 adc.setup(LOCKIN_ADC_PIN, 0);
mbedalvaro 34:1244fa3f2559 58 //adc.select(LOCKIN_ADC_PIN);
mbedalvaro 34:1244fa3f2559 59 adc.interrupt_state(LOCKIN_ADC_PIN, 0);
mbedalvaro 34:1244fa3f2559 60 //adc.append(LOCKIN_ADC_PIN, catchInterupt);
mbedalvaro 34:1244fa3f2559 61 }
mbedalvaro 34:1244fa3f2559 62 }
mbedalvaro 34:1244fa3f2559 63
mbedalvaro 34:1244fa3f2559 64 void Lockin::initPWM(){
mbedalvaro 34:1244fa3f2559 65
mbedalvaro 34:1244fa3f2559 66 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency; // half shared periof
mbedalvaro 34:1244fa3f2559 67 _currentMR[0] = int(1.0 * MBEDFREQUENCY / refFrequency); //save the current value of MR0 (shared periof) //147
mbedalvaro 34:1244fa3f2559 68 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1 //40
mbedalvaro 34:1244fa3f2559 69 _currentMR[2] = int(_currentMR[1] + halfPeriod); //save the current value of MR2 //40+73
mbedalvaro 34:1244fa3f2559 70 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1 //0
mbedalvaro 34:1244fa3f2559 71 _currentMR[4] = int(_currentMR[3] + halfPeriod); //save the current value of MR2 //73
mbedalvaro 34:1244fa3f2559 72
mbedalvaro 34:1244fa3f2559 73
mbedalvaro 34:1244fa3f2559 74 // set PWM:
mbedalvaro 34:1244fa3f2559 75 LPC_PWM1->TCR = (1 << 1); // Reset counter, disable PWM
mbedalvaro 34:1244fa3f2559 76 LPC_SC->PCLKSEL0 &= ~(0x3 << 12);
mbedalvaro 34:1244fa3f2559 77 LPC_SC->PCLKSEL0 |= (1 << 12); // Set peripheral clock divider to /1, i.e. system clock
mbedalvaro 34:1244fa3f2559 78
mbedalvaro 34:1244fa3f2559 79 LPC_PWM1->PCR |= 0x0014; // Double edge PWM for PWM2,4
mbedalvaro 34:1244fa3f2559 80
mbedalvaro 34:1244fa3f2559 81 LPC_PWM1->MR0 = _currentMR[0]; // Match Register 0 is shared period counter for all PWM1
mbedalvaro 34:1244fa3f2559 82
mbedalvaro 34:1244fa3f2559 83 LPC_PWM1->MR1 = _currentMR[1]; // Match Register 1 is laser rising edge counter
mbedalvaro 34:1244fa3f2559 84 LPC_PWM1->MR2 = _currentMR[2]; // Match Register 2 is laser falling edge counter
mbedalvaro 34:1244fa3f2559 85 LPC_PWM1->MR3 = _currentMR[3]; // Match Register 3 is lock-in rising edge counter
mbedalvaro 34:1244fa3f2559 86 LPC_PWM1->MR4 = _currentMR[4]; // Match Register 4 is lock-in falling edge counter
mbedalvaro 34:1244fa3f2559 87
mbedalvaro 34:1244fa3f2559 88 LPC_PWM1->LER |= 1; // Start updating at next period start
mbedalvaro 34:1244fa3f2559 89 LPC_PWM1->TCR = (1 << 0) || (1 << 3); // Enable counter and PWM
mbedalvaro 34:1244fa3f2559 90 }
mbedalvaro 34:1244fa3f2559 91
mbedalvaro 34:1244fa3f2559 92 //change the frequency of the PWM after initPWM()
mbedalvaro 34:1244fa3f2559 93 void Lockin::setPWMFrequency(float freq){
mbedalvaro 34:1244fa3f2559 94 refFrequency = freq;
mbedalvaro 34:1244fa3f2559 95 _currentMR[0] = int(MBEDFREQUENCY / refFrequency); //save the current value of MR0
mbedalvaro 34:1244fa3f2559 96 LPC_PWM1->MR0 = _currentMR[0]; //update PWM shared period register
mbedalvaro 34:1244fa3f2559 97 LPC_PWM1->LER |= 1; //update PWM
mbedalvaro 34:1244fa3f2559 98 }
mbedalvaro 34:1244fa3f2559 99
mbedalvaro 34:1244fa3f2559 100 //change the phase shift of the sensing laser after initPWM()
mbedalvaro 34:1244fa3f2559 101 void Lockin::setLaserPhaseShift(float phaseShift){
mbedalvaro 34:1244fa3f2559 102 phaseShiftLaser = phaseShift;
mbedalvaro 34:1244fa3f2559 103 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 34:1244fa3f2559 104 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1
mbedalvaro 34:1244fa3f2559 105 _currentMR[2] = _currentMR[1] + halfPeriod; //save the current value of MR2
mbedalvaro 34:1244fa3f2559 106
mbedalvaro 34:1244fa3f2559 107 LPC_PWM1->MR1 = _currentMR[1]; //update Laser rising edge match register
mbedalvaro 34:1244fa3f2559 108 LPC_PWM1->MR2 = _currentMR[2]; //update Laser faling edge match register
mbedalvaro 34:1244fa3f2559 109 }
mbedalvaro 34:1244fa3f2559 110
mbedalvaro 34:1244fa3f2559 111 //change the phase shift of the lock-in after initPWM()
mbedalvaro 34:1244fa3f2559 112 void Lockin::setLockinPhaseShift(float phaseShift){
mbedalvaro 34:1244fa3f2559 113 phaseShiftLockin = phaseShift;
mbedalvaro 34:1244fa3f2559 114 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 34:1244fa3f2559 115 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1
mbedalvaro 34:1244fa3f2559 116 _currentMR[4] = _currentMR[3] + halfPeriod; //save the current value of MR2
mbedalvaro 34:1244fa3f2559 117
mbedalvaro 34:1244fa3f2559 118 LPC_PWM1->MR3 = _currentMR[3]; //update lock-in rising edge match register
mbedalvaro 34:1244fa3f2559 119 LPC_PWM1->MR4 = _currentMR[4]; //update lock-in faling edge match register
mbedalvaro 34:1244fa3f2559 120 }
mbedalvaro 34:1244fa3f2559 121
mbedalvaro 34:1244fa3f2559 122
mbedalvaro 34:1244fa3f2559 123 void Lockin::setLaserPower(bool power){
mbedalvaro 34:1244fa3f2559 124 if(power){
mbedalvaro 34:1244fa3f2559 125 LPC_PWM1->MR1 = _currentMR[1];
mbedalvaro 34:1244fa3f2559 126 LPC_PWM1->MR2 = _currentMR[2];
mbedalvaro 34:1244fa3f2559 127 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 34:1244fa3f2559 128 }
mbedalvaro 34:1244fa3f2559 129 else{
mbedalvaro 34:1244fa3f2559 130 LPC_PWM1->MR1 = 0; //set rising edge at 0
mbedalvaro 34:1244fa3f2559 131 LPC_PWM1->MR2 = 0; //set falling edge at 0
mbedalvaro 34:1244fa3f2559 132 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 34:1244fa3f2559 133 }
mbedalvaro 34:1244fa3f2559 134 }
mbedalvaro 34:1244fa3f2559 135
mbedalvaro 34:1244fa3f2559 136 void Lockin::clearBuffer(){
mbedalvaro 34:1244fa3f2559 137 for(int i=0; i<BUFFER_SIZE; i++){
mbedalvaro 34:1244fa3f2559 138 buffer[i] = 0;
mbedalvaro 34:1244fa3f2559 139 }
mbedalvaro 34:1244fa3f2559 140 buffer_pos = BUFFER_SIZE;
mbedalvaro 34:1244fa3f2559 141 }
mbedalvaro 34:1244fa3f2559 142
mbedalvaro 34:1244fa3f2559 143 /*
mbedalvaro 34:1244fa3f2559 144 void Lockin::catchInterupt(uint32_t value){
mbedalvaro 34:1244fa3f2559 145 buffer_pos++;
mbedalvaro 34:1244fa3f2559 146 buffer_pos%=BUFFER_SIZE;
mbedalvaro 34:1244fa3f2559 147 buffer[buffer_pos] = value;
mbedalvaro 34:1244fa3f2559 148 }
mbedalvaro 34:1244fa3f2559 149 */
mbedalvaro 34:1244fa3f2559 150
mbedalvaro 34:1244fa3f2559 151 //****** aquisition method *****//
mbedalvaro 34:1244fa3f2559 152 unsigned short Lockin::getLastValue(){
mbedalvaro 34:1244fa3f2559 153 return buffer[buffer_pos];
mbedalvaro 34:1244fa3f2559 154 }
mbedalvaro 34:1244fa3f2559 155
mbedalvaro 34:1244fa3f2559 156 unsigned short Lockin::getSmoothValue(){
mbedalvaro 34:1244fa3f2559 157 unsigned short smoothValue = buffer[0];
mbedalvaro 34:1244fa3f2559 158 for(int i=1; i<BUFFER_SIZE; i++){
mbedalvaro 34:1244fa3f2559 159 smoothValue += buffer[i];
mbedalvaro 34:1244fa3f2559 160 }
mbedalvaro 34:1244fa3f2559 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 34:1244fa3f2559 162
mbedalvaro 34:1244fa3f2559 163 return smoothValue;
mbedalvaro 34:1244fa3f2559 164 }
mbedalvaro 34:1244fa3f2559 165
mbedalvaro 34:1244fa3f2559 166 unsigned short Lockin::getMedianValue(){
mbedalvaro 34:1244fa3f2559 167 //this method applies a median filter to the buffer
mbedalvaro 34:1244fa3f2559 168 //It reduces the salt-and-pepper noise
mbedalvaro 34:1244fa3f2559 169 //It seems that this noise is very strong on certain mBed board, but not all...
mbedalvaro 34:1244fa3f2559 170
mbedalvaro 34:1244fa3f2559 171 // unsigned short orderedBuffer[BUFFER_SIZE_MEDIAN];
mbedalvaro 34:1244fa3f2559 172
mbedalvaro 34:1244fa3f2559 173 //sort half of the buffer:
mbedalvaro 34:1244fa3f2559 174
mbedalvaro 34:1244fa3f2559 175 //copy buffer
mbedalvaro 34:1244fa3f2559 176 for(int i=0; i<BUFFER_SIZE_MEDIAN; i++){
mbedalvaro 34:1244fa3f2559 177 orderedBuffer[i] = buffer[(buffer_pos+BUFFER_SIZE-i+DELAY_BUFFER_MEDIAN)%BUFFER_SIZE];
mbedalvaro 34:1244fa3f2559 178 }
mbedalvaro 34:1244fa3f2559 179
mbedalvaro 34:1244fa3f2559 180 //order buffer
mbedalvaro 34:1244fa3f2559 181 for(int i=0; i<BUFFER_SIZE_MEDIAN-1; i++){
mbedalvaro 34:1244fa3f2559 182 int minPos = i;
mbedalvaro 34:1244fa3f2559 183
mbedalvaro 34:1244fa3f2559 184 //get min
mbedalvaro 34:1244fa3f2559 185 for(int j=i+1; j<BUFFER_SIZE_MEDIAN; j++){
mbedalvaro 34:1244fa3f2559 186 if(orderedBuffer[j] < orderedBuffer[minPos]) minPos = j;
mbedalvaro 34:1244fa3f2559 187 }
mbedalvaro 34:1244fa3f2559 188
mbedalvaro 34:1244fa3f2559 189 //swap min to the right position
mbedalvaro 34:1244fa3f2559 190 if(minPos != i){
mbedalvaro 34:1244fa3f2559 191 int tmpMin = orderedBuffer[minPos];
mbedalvaro 34:1244fa3f2559 192 orderedBuffer[minPos] = orderedBuffer[i];
mbedalvaro 34:1244fa3f2559 193 orderedBuffer[i] = tmpMin;
mbedalvaro 34:1244fa3f2559 194 }
mbedalvaro 34:1244fa3f2559 195 }
mbedalvaro 34:1244fa3f2559 196
mbedalvaro 34:1244fa3f2559 197 return orderedBuffer[BUFFER_SIZE_MEDIAN/2];
mbedalvaro 34:1244fa3f2559 198 }