File content as of revision 11:dd860c2e12ec:

# include "mbed.h"
# include "Timer.h"

# include <stdlib.h>
# include <time.h>
# include <limits>
# include <queue>

# define NUM_HOLES 32
# define CIRCUMFRENCE_CM 48.6946861

# define LIGHT_SENSOR_PIN p15
# define FLASH_THRESHOLD 0.97


AnalogIn lightSensorVoltage(LIGHT_SENSOR_PIN);
Serial pc(USBTX, USBRX);

DigitalOut myled(LED1);

int lastFlash = 0;
float prevVoltReading = 0.0;
float currVoltReading = 0.0;
float miliPerRotation = std::numeric_limits<float>::max();

//float getAverage(queue<float> q) {
//printf("g");
//    float sum = 0;
//    while(!q.empty()) {
//printf("h");
//        sum += q.front();
//        q.pop();
//    }
//    
//    return sum / q.size();
//}

void sendFloat(float value) {
    for (int i=0; i<4; i++)
        pc.putc(*(((char*) &value)+i));
}

int main() {
    Timer timer;
    timer.start();
    int currTime = 0;
    int prevTime = 0;
    
    float velocity = 0;
    
    sendFloat(0);
    while(1) {
        currVoltReading = lightSensorVoltage.read();
//printf("volt %f\n", currVoltReading);
        if(currVoltReading - prevVoltReading > 0.02) {
            currTime = timer.read_ms();
//printf("currTime %i\n", currTime);
//printf("prevTime %i\n", prevTime);
            miliPerRotation = (currTime - prevTime) * NUM_HOLES;
//printf("time diff %i\n", currTime - prevTime);
//printf("MPRs %f\n", miliPerRotation);
            
            prevTime = currTime;
            velocity = CIRCUMFRENCE_CM * 1000 / miliPerRotation;
            
            sendFloat(velocity);
        }
//printf("velocity %f\n", velocity);
        prevVoltReading = currVoltReading;
        //wait(0.05);
    }
}