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@14:0fc33a3a7b4b, 2012-04-12 (annotated)

Committer:
mbedalvaro
Date:
Thu Apr 12 13:02:59 2012 +0000
Revision:
14:0fc33a3a7b4b
Parent:
10:6f8e48dca1bd
Child:
23:bf666fcc61bc
checking old version, need to branch

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbedalvaro 0:345b3bc7a0ea 1 #include "lockin.h"
mbedalvaro 0:345b3bc7a0ea 2
mbedalvaro 0:345b3bc7a0ea 3 Lockin lockin=Lockin();//pre-instanciation of object lockin with inter-file scope (declared extern in .h file)
mbedalvaro 0:345b3bc7a0ea 4
mbedalvaro 10:6f8e48dca1bd 5
mbedalvaro 10:6f8e48dca1bd 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 0:345b3bc7a0ea 7 void catchInterupt(uint32_t value){
mbedalvaro 0:345b3bc7a0ea 8 lockin.buffer_pos=(lockin.buffer_pos+1)%BUFFER_SIZE;
mbedalvaro 10:6f8e48dca1bd 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 0:345b3bc7a0ea 10 }
mbedalvaro 0:345b3bc7a0ea 11
mbedalvaro 0:345b3bc7a0ea 12 // PWM generation is configure as double edge
mbedalvaro 0:345b3bc7a0ea 13 // MR0 (Match Register 0) control the frequency
mbedalvaro 0:345b3bc7a0ea 14 // 'pwm2' uses MR1 and MR2 (rising and falling edges)
mbedalvaro 0:345b3bc7a0ea 15 // 'pwm4' uses MR3 and MR4 (rising and falling edges)
mbedalvaro 0:345b3bc7a0ea 16 // 'pwm1' and 'pwm3' cannot be used since they share the same Match Register
mbedalvaro 0:345b3bc7a0ea 17 // for the moment, all PWM pin are set as output:
mbedalvaro 0:345b3bc7a0ea 18 PwmOut pwm1(p26);
mbedalvaro 0:345b3bc7a0ea 19 PwmOut pwm2(p25); //also defined as LOCKIN_LASER_PIN
mbedalvaro 0:345b3bc7a0ea 20 PwmOut pwm3(p24);
mbedalvaro 0:345b3bc7a0ea 21 PwmOut pwm4(p23); //also defined as LOCKIN_REF_PIN
mbedalvaro 0:345b3bc7a0ea 22 PwmOut pwm5(p22);
mbedalvaro 0:345b3bc7a0ea 23 PwmOut pwm6(p21);
mbedalvaro 0:345b3bc7a0ea 24
mbedalvaro 0:345b3bc7a0ea 25 //Lockin::Lockin(){}
mbedalvaro 0:345b3bc7a0ea 26
mbedalvaro 0:345b3bc7a0ea 27 void Lockin::init(){
mbedalvaro 0:345b3bc7a0ea 28
mbedalvaro 0:345b3bc7a0ea 29 //configure PWM for the laser and the Lockin
mbedalvaro 0:345b3bc7a0ea 30 refFreq = 147;
mbedalvaro 0:345b3bc7a0ea 31 offsetRef = 40;
mbedalvaro 0:345b3bc7a0ea 32 halfRefFreq = refFreq / 2;
mbedalvaro 0:345b3bc7a0ea 33
mbedalvaro 0:345b3bc7a0ea 34 refFrequency = 653; //init the lock-in frequency at 653 kHz
mbedalvaro 0:345b3bc7a0ea 35 phaseShiftLaser = 0.546; //offset of 54% for the laser signal
mbedalvaro 0:345b3bc7a0ea 36 phaseShiftLockin = 0; //no offset for the lock-in reference
mbedalvaro 0:345b3bc7a0ea 37 initPWM();
mbedalvaro 0:345b3bc7a0ea 38
mbedalvaro 0:345b3bc7a0ea 39 //configure ADC:
mbedalvaro 0:345b3bc7a0ea 40 clearBuffer();
mbedalvaro 0:345b3bc7a0ea 41
mbedalvaro 0:345b3bc7a0ea 42 adc.startmode(0,0);
mbedalvaro 0:345b3bc7a0ea 43 adc.burst(1);
mbedalvaro 0:345b3bc7a0ea 44 adc.setup(LOCKIN_ADC_PIN, 1);
mbedalvaro 0:345b3bc7a0ea 45 adc.select(LOCKIN_ADC_PIN);
mbedalvaro 0:345b3bc7a0ea 46 adc.interrupt_state(LOCKIN_ADC_PIN, 1);
mbedalvaro 0:345b3bc7a0ea 47 adc.append(LOCKIN_ADC_PIN, catchInterupt);
mbedalvaro 0:345b3bc7a0ea 48 }
mbedalvaro 0:345b3bc7a0ea 49
mbedalvaro 0:345b3bc7a0ea 50
mbedalvaro 0:345b3bc7a0ea 51 void Lockin::initPWM(){
mbedalvaro 0:345b3bc7a0ea 52
mbedalvaro 0:345b3bc7a0ea 53 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency; // half shared periof
mbedalvaro 0:345b3bc7a0ea 54 _currentMR[0] = int(1.0 * MBEDFREQUENCY / refFrequency); //save the current value of MR0 (shared periof) //147
mbedalvaro 0:345b3bc7a0ea 55 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1 //40
mbedalvaro 0:345b3bc7a0ea 56 _currentMR[2] = int(_currentMR[1] + halfPeriod); //save the current value of MR2 //40+73
mbedalvaro 0:345b3bc7a0ea 57 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1 //0
mbedalvaro 0:345b3bc7a0ea 58 _currentMR[4] = int(_currentMR[3] + halfPeriod); //save the current value of MR2 //73
mbedalvaro 0:345b3bc7a0ea 59
mbedalvaro 0:345b3bc7a0ea 60
mbedalvaro 0:345b3bc7a0ea 61 // set PWM:
mbedalvaro 0:345b3bc7a0ea 62 LPC_PWM1->TCR = (1 << 1); // Reset counter, disable PWM
mbedalvaro 0:345b3bc7a0ea 63 LPC_SC->PCLKSEL0 &= ~(0x3 << 12);
mbedalvaro 0:345b3bc7a0ea 64 LPC_SC->PCLKSEL0 |= (1 << 12); // Set peripheral clock divider to /1, i.e. system clock
mbedalvaro 0:345b3bc7a0ea 65
mbedalvaro 0:345b3bc7a0ea 66 LPC_PWM1->PCR |= 0x0014; // Double edge PWM for PWM2,4
mbedalvaro 0:345b3bc7a0ea 67
mbedalvaro 0:345b3bc7a0ea 68 LPC_PWM1->MR0 = _currentMR[0]; // Match Register 0 is shared period counter for all PWM1
mbedalvaro 0:345b3bc7a0ea 69
mbedalvaro 0:345b3bc7a0ea 70 LPC_PWM1->MR1 = _currentMR[1]; // Match Register 1 is laser rising edge counter
mbedalvaro 0:345b3bc7a0ea 71 LPC_PWM1->MR2 = _currentMR[2]; // Match Register 2 is laser falling edge counter
mbedalvaro 0:345b3bc7a0ea 72 LPC_PWM1->MR3 = _currentMR[3]; // Match Register 3 is lock-in rising edge counter
mbedalvaro 0:345b3bc7a0ea 73 LPC_PWM1->MR4 = _currentMR[4]; // Match Register 4 is lock-in falling edge counter
mbedalvaro 0:345b3bc7a0ea 74
mbedalvaro 0:345b3bc7a0ea 75 LPC_PWM1->LER |= 1; // Start updating at next period start
mbedalvaro 0:345b3bc7a0ea 76 LPC_PWM1->TCR = (1 << 0) || (1 << 3); // Enable counter and PWM
mbedalvaro 0:345b3bc7a0ea 77 }
mbedalvaro 0:345b3bc7a0ea 78
mbedalvaro 0:345b3bc7a0ea 79 //change the frequency of the PWM after initPWM()
mbedalvaro 0:345b3bc7a0ea 80 void Lockin::setPWMFrequency(float freq){
mbedalvaro 0:345b3bc7a0ea 81 refFrequency = freq;
mbedalvaro 0:345b3bc7a0ea 82 _currentMR[0] = int(MBEDFREQUENCY / refFrequency); //save the current value of MR0
mbedalvaro 0:345b3bc7a0ea 83 LPC_PWM1->MR0 = _currentMR[0]; //update PWM shared period register
mbedalvaro 0:345b3bc7a0ea 84 LPC_PWM1->LER |= 1; //update PWM
mbedalvaro 0:345b3bc7a0ea 85 }
mbedalvaro 0:345b3bc7a0ea 86
mbedalvaro 0:345b3bc7a0ea 87 //change the phase shift of the sensing laser after initPWM()
mbedalvaro 0:345b3bc7a0ea 88 void Lockin::setLaserPhaseShift(float phaseShift){
mbedalvaro 0:345b3bc7a0ea 89 phaseShiftLaser = phaseShift;
mbedalvaro 0:345b3bc7a0ea 90 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 0:345b3bc7a0ea 91 _currentMR[1] = int(phaseShiftLaser * halfPeriod); //save the current value of MR1
mbedalvaro 0:345b3bc7a0ea 92 _currentMR[2] = _currentMR[1] + halfPeriod; //save the current value of MR2
mbedalvaro 0:345b3bc7a0ea 93
mbedalvaro 0:345b3bc7a0ea 94 LPC_PWM1->MR1 = _currentMR[1]; //update Laser rising edge match register
mbedalvaro 0:345b3bc7a0ea 95 LPC_PWM1->MR2 = _currentMR[2]; //update Laser faling edge match register
mbedalvaro 0:345b3bc7a0ea 96 }
mbedalvaro 0:345b3bc7a0ea 97
mbedalvaro 0:345b3bc7a0ea 98 //change the phase shift of the lock-in after initPWM()
mbedalvaro 0:345b3bc7a0ea 99 void Lockin::setLockinPhaseShift(float phaseShift){
mbedalvaro 0:345b3bc7a0ea 100 phaseShiftLockin = phaseShift;
mbedalvaro 0:345b3bc7a0ea 101 float halfPeriod = 0.5 * MBEDFREQUENCY / refFrequency;
mbedalvaro 0:345b3bc7a0ea 102 _currentMR[3] = int(phaseShiftLockin * halfPeriod); //save the current value of MR1
mbedalvaro 0:345b3bc7a0ea 103 _currentMR[4] = _currentMR[3] + halfPeriod; //save the current value of MR2
mbedalvaro 0:345b3bc7a0ea 104
mbedalvaro 0:345b3bc7a0ea 105 LPC_PWM1->MR3 = _currentMR[3]; //update lock-in rising edge match register
mbedalvaro 0:345b3bc7a0ea 106 LPC_PWM1->MR4 = _currentMR[4]; //update lock-in faling edge match register
mbedalvaro 0:345b3bc7a0ea 107 }
mbedalvaro 0:345b3bc7a0ea 108
mbedalvaro 0:345b3bc7a0ea 109
mbedalvaro 0:345b3bc7a0ea 110 void Lockin::setLaserPower(bool power){
mbedalvaro 0:345b3bc7a0ea 111 if(power){
mbedalvaro 0:345b3bc7a0ea 112 LPC_PWM1->MR1 = _currentMR[1];
mbedalvaro 0:345b3bc7a0ea 113 LPC_PWM1->MR2 = _currentMR[2];
mbedalvaro 0:345b3bc7a0ea 114 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 0:345b3bc7a0ea 115 }
mbedalvaro 0:345b3bc7a0ea 116 else{
mbedalvaro 0:345b3bc7a0ea 117 LPC_PWM1->MR1 = 0; //set rising edge at 0
mbedalvaro 0:345b3bc7a0ea 118 LPC_PWM1->MR2 = 0; //set falling edge at 0
mbedalvaro 0:345b3bc7a0ea 119 LPC_PWM1->LER |= 1; // update PWM at the next period
mbedalvaro 0:345b3bc7a0ea 120 }
mbedalvaro 0:345b3bc7a0ea 121 }
mbedalvaro 0:345b3bc7a0ea 122
mbedalvaro 0:345b3bc7a0ea 123 void Lockin::clearBuffer(){
mbedalvaro 0:345b3bc7a0ea 124 for(int i=0; i<BUFFER_SIZE; i++){
mbedalvaro 0:345b3bc7a0ea 125 buffer[i] = 0;
mbedalvaro 0:345b3bc7a0ea 126 }
mbedalvaro 0:345b3bc7a0ea 127 buffer_pos = BUFFER_SIZE;
mbedalvaro 0:345b3bc7a0ea 128 }
mbedalvaro 0:345b3bc7a0ea 129
mbedalvaro 0:345b3bc7a0ea 130 /*
mbedalvaro 0:345b3bc7a0ea 131 void Lockin::catchInterupt(uint32_t value){
mbedalvaro 0:345b3bc7a0ea 132 buffer_pos++;
mbedalvaro 0:345b3bc7a0ea 133 buffer_pos%=BUFFER_SIZE;
mbedalvaro 0:345b3bc7a0ea 134 buffer[buffer_pos] = value;
mbedalvaro 0:345b3bc7a0ea 135 }
mbedalvaro 0:345b3bc7a0ea 136 */
mbedalvaro 0:345b3bc7a0ea 137
mbedalvaro 0:345b3bc7a0ea 138 //****** aquisition method *****//
mbedalvaro 10:6f8e48dca1bd 139 unsigned short Lockin::getLastValue(){
mbedalvaro 0:345b3bc7a0ea 140 return buffer[buffer_pos];
mbedalvaro 0:345b3bc7a0ea 141 }
mbedalvaro 0:345b3bc7a0ea 142
mbedalvaro 10:6f8e48dca1bd 143 unsigned short Lockin::getSmoothValue(){
mbedalvaro 10:6f8e48dca1bd 144 unsigned short smoothValue = buffer[0];
mbedalvaro 0:345b3bc7a0ea 145 for(int i=1; i<BUFFER_SIZE; i++){
mbedalvaro 0:345b3bc7a0ea 146 smoothValue += buffer[i];
mbedalvaro 0:345b3bc7a0ea 147 }
mbedalvaro 10:6f8e48dca1bd 148 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 0:345b3bc7a0ea 149
mbedalvaro 0:345b3bc7a0ea 150 return smoothValue;
mbedalvaro 0:345b3bc7a0ea 151 }
mbedalvaro 0:345b3bc7a0ea 152
mbedalvaro 10:6f8e48dca1bd 153 unsigned short Lockin::getMedianValue(){
mbedalvaro 0:345b3bc7a0ea 154 //this method applies a median filter to the buffer
mbedalvaro 0:345b3bc7a0ea 155 //It reduces the salt-and-pepper noise
mbedalvaro 0:345b3bc7a0ea 156 //It seems that this noise is very strong on certain mBed board, but not all...
mbedalvaro 0:345b3bc7a0ea 157
mbedalvaro 14:0fc33a3a7b4b 158 // unsigned short orderedBuffer[BUFFER_SIZE_MEDIAN];
mbedalvaro 0:345b3bc7a0ea 159
mbedalvaro 0:345b3bc7a0ea 160 //sort half of the buffer:
mbedalvaro 0:345b3bc7a0ea 161
mbedalvaro 0:345b3bc7a0ea 162 //copy buffer
mbedalvaro 0:345b3bc7a0ea 163 for(int i=0; i<BUFFER_SIZE_MEDIAN; i++){
mbedalvaro 0:345b3bc7a0ea 164 orderedBuffer[i] = buffer[(buffer_pos+BUFFER_SIZE-i+DELAY_BUFFER_MEDIAN)%BUFFER_SIZE];
mbedalvaro 0:345b3bc7a0ea 165 }
mbedalvaro 0:345b3bc7a0ea 166
mbedalvaro 0:345b3bc7a0ea 167 //order buffer
mbedalvaro 0:345b3bc7a0ea 168 for(int i=0; i<BUFFER_SIZE_MEDIAN-1; i++){
mbedalvaro 0:345b3bc7a0ea 169 int minPos = i;
mbedalvaro 0:345b3bc7a0ea 170
mbedalvaro 0:345b3bc7a0ea 171 //get min
mbedalvaro 0:345b3bc7a0ea 172 for(int j=i+1; j<BUFFER_SIZE_MEDIAN; j++){
mbedalvaro 0:345b3bc7a0ea 173 if(orderedBuffer[j] < orderedBuffer[minPos]) minPos = j;
mbedalvaro 0:345b3bc7a0ea 174 }
mbedalvaro 0:345b3bc7a0ea 175
mbedalvaro 0:345b3bc7a0ea 176 //swap min to the right position
mbedalvaro 0:345b3bc7a0ea 177 if(minPos != i){
mbedalvaro 0:345b3bc7a0ea 178 int tmpMin = orderedBuffer[minPos];
mbedalvaro 0:345b3bc7a0ea 179 orderedBuffer[minPos] = orderedBuffer[i];
mbedalvaro 0:345b3bc7a0ea 180 orderedBuffer[i] = tmpMin;
mbedalvaro 0:345b3bc7a0ea 181 }
mbedalvaro 0:345b3bc7a0ea 182 }
mbedalvaro 0:345b3bc7a0ea 183
mbedalvaro 0:345b3bc7a0ea 184 return orderedBuffer[BUFFER_SIZE_MEDIAN/2];
mbedalvaro 0:345b3bc7a0ea 185 }