File content as of revision 0:c5d947408ea3:

#include "mbed.h"

//Program to control a sun tracking platform for solar panels.
//Details of the hardware can be found at mdpub.com

void stop();
void moveW();
void moveE();
void resetE();
void readcells();

Serial pc(USBTX, USBRX); 
AnalogIn Ecell(p19), Wcell(p20);
DigitalIn ELimit(p5), WLimit(p6);
InterruptIn EInt(p8), WInt(p9);
DigitalOut MotorOn(p22), Direction(p21);
DigitalOut MyLed1(LED1), MyLed2(LED2);
int AtReset;
float Sunup, Threshold, RunTime;
float Eval, Wval, Ambval;

void stop() { //Stop the drive motor. The interrupt calls this if either limit switch opens.
    pc.printf("Stop!\n\r"); //Print "Stop!" to the serial terminal for calibration/troubleshooting purposes.
    Direction = 0; //Open the direction and motor drive relays.
    MotorOn = 0;
}

void moveW() { //Move the panel W.
    Direction = 0; //Set direction to W.
    MotorOn = 1; //Run the motor.
    pc.printf("Motor on W!\n\r"); //Print "Motor on W!" to the serial terminal for calibration/troubleshooting purposes.
    wait(RunTime); //Run the motor for RunTime.
    MotorOn = 0; //Turn the motor off.
    AtReset = 0; //Set AtReset to 0 because we are not all the way E.
}

void moveE() { //Move the panel E.
    Direction = 1; //Set direction to E.
    wait(0.5);
    MotorOn = 1; //Run the motor.
    pc.printf("Motor on E!\n\r"); //Print "Motor on E!" to the serial terminal for calibration/troubleshooting purposes.
    wait(RunTime); //Run the motor for RunTime.
    MotorOn = 0; //Open the motor power and direction relays.
    Direction = 0;
}    

void resetE() { //Move the panel all the way E after dark so that the sun will shine on it after sunrise.
    while (!ELimit) { //While the E limit switch is closed.
        moveE();
    }
    AtReset = 1; //Set AtReset to 1 since we are now all the way E.
}

void readcells() {  //Read the values of the E & W cells 5 times each and average the values.
    int i;
    for(i = 0; i < 5; i++){ //Loop 5 times
        Wval += Wcell.read(); //Read the values
        Eval += Ecell.read();
    }
    Wval = Wval / 5; //Average the values
    Eval = Eval / 5;
}

int main() {
    pc.printf("Powered Up\n\r"); //Print "Powered Up" to the serial terminal for calibration/troubleshooting purposes.
    EInt.rise(&stop); //Call motor stop if either limit switch opens.
    WInt.rise(&stop);
    AtReset = 0; //1=at E limit.
    Sunup = 0.08; //Ambient light threshold at which sun is considered to be up.
    Threshold = 0.035; //Max allowed difference between E & W inputs.
    RunTime = 1.25; //How long the motor shold run on each move. (about 6 deg/sec after slight turn-on delay) 
        while(1) {  //Loop forever.
        readcells();  //Read the values of the E & W cells.
        Ambval = Wval + Eval; //Find the ambient light level
        MyLed1 = ELimit; MyLed2 = WLimit;
        pc.printf("%f  %f  %f\r\n", Wval, Eval, Ambval); //Print the west, east, and ambient values to the serial terminal for calibration purposes.
        if ((Ambval > (Sunup + 0.4)) ){ //If the sun is up ...
            if (((Wval-Eval) > Threshold) && !WLimit){ //If the W cell is illuminated by more than the threshhold and the W limit swich is closed...
                moveW(); //Move the panel W.
            }
            if (((Eval-Wval) > Threshold) && !ELimit){ //If the E cell is illuminated by more than the threshhold and the E limit swich is closed...
                moveE(); //Move the panel E.
            }            
        }    
        if ((Ambval < Sunup) && !AtReset) { //If the sun is down and the panel is not reset to the E...
            resetE(); //Move the panel to the E reset position.
        }
        wait(60); //Kill time. Set to 5 seconds during calibration/testing.
    }
}