Diff: hardwareIO/lockin.h

Revision:

41:74e24a0e6e50

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hardwareIO/lockin.h	Wed Oct 16 17:26:13 2013 +0000
@@ -0,0 +1,80 @@
+#ifndef MBED_LOCKIN_H
+#define MBED_LOCKIN_H
+
+#include "mbed.h"
+#include "adc.h"
+
+#define MBEDFREQUENCY 96000 //frequency of the mBed in KHz
+
+//#define I_Volts_SAT 5 // this is 5V (the saturation voltage for the APD+LockIn+ADC, being it the arduino (when in normal mode) or the SPI. This saturation voltage could be different for each mode!?
+
+#define LOCKIN_ADC_PIN      p18 //ADC pin : connect to lockin "output"
+
+#define LOCKIN_REF_PIN      p23 //PWM pin : connect to lockin reference signal.
+#define LOCKIN_LASER_PIN    p25 //PWM pin : connect to laser control - note: the red laser by default, but could be a fourth IR laser...
+// p21 to p25 are used by the PWM timers even if only 2 pin are connected to the circuit
+
+#define BUFFER_SIZE 15
+#define BUFFER_SIZE_MEDIAN 5
+#define DELAY_BUFFER_MEDIAN 0
+
+
+class Lockin {
+public:
+    // default constructor (untouched!)
+    // Lockin();
+    
+    // initialization of object modes (could have parameters):
+    void init();
+    
+    void initPWM(); //setup the laser and reference signal used by the lockin
+    void setPWMFrequency(float freq); //change the shared period of the pwm signals
+    void setLaserPhaseShift(float phaseShift); //change the phase shift of the laser (from 0 to 1)
+    void setLockinPhaseShift(float phaseShift); //change the phase shift of the lock-in (from 0 to 1)
+    //future works: 
+    //add function to change frequency or offset with a potentiometer for exemple
+    //or scan the best frequency...
+    
+    void setLaserPower(bool power); //change PWM settings to turn on/off the laser
+    
+    void setADC_forLockin(int mode); //1 set, 0 reset (this is needed because we may use normal ADC from pins, or a special mode for the lockin - fast ADC)
+    
+    unsigned short getSmoothValue(); //return the average of the value stored on the buffer
+    unsigned short getLastValue(); //return the last conversion of the ADC
+    unsigned short getMedianValue(); //return the median value of the buffer
+    //it is just a begining; we can add more complex method for denoising for exemple
+    //maybe, needs function to start and stop the lockin
+    
+    void clearBuffer();
+    
+    //can be private
+    //void catchInterupt(uint32_t value);
+    
+    //variables
+    unsigned short buffer[BUFFER_SIZE];  // does not need to be a float - in fact values are from 0 to 4096 (i.e., 
+    //unsigned short int buffer[BUFFER_SIZE]; // this is two bytes (0 to 65535)
+    unsigned short orderedBuffer[BUFFER_SIZE_MEDIAN]; // for computation of the MEDIAN value
+    int buffer_pos;
+    
+    float refFrequency;     // frequency of sensing laser and lock-in (in KHz)
+    //Phase shift of the pwm signals (from 0 to 1):
+    //it corresponds to a percentage of the half of a period
+    //(no phase shift ==> 0% / 90deg phase shift ==> 100%)
+    float phaseShiftLaser;  // phase shift of the sensing laser 
+    float phaseShiftLockin; // phase shift of the lock-in reference
+    
+    int refFreq; //frequency of the lockin
+    int offsetRef; //offset between the laser signal and the lockin reference signal
+    int halfRefFreq;
+    
+private:
+    // PWM match register value are saved as private 
+    // to avoid computation when turn on/off for exemple
+    int _currentMR[6]; 
+    
+
+};
+
+extern Lockin lockin;
+
+#endif