Make a sketch using getPhoto() to control the LED using proportional control. He

Question

Make a sketch using getPhoto() to control the LED using proportional control. Here is an outline: Setout=0; Loop for k=1 to 100 Set analogWrite() to out Wait 100ms. Measure V using getPhoto Serial.println V Define err ie e=Vset-V; Define out=P*e; Make sure out is between [0 255]. Serial.println theta and out End loop Find the largest value of P=Pmax that does not causes the V to oscillate. How does it compare to your estimate from part I? What is the value of the error for the largest P that will not oscillate? Plot V and out verses step k from above for Pmax, Pmax/2, and Pmax/10. Add Integral control. Initialize es to 0 before the loop and after line g above add es=es+e; Then change line h to out=P*e+I*res. Find values of P=P0 and I=I0 that give good control. Plot V and out verses step k for (P0.I0), (P0, I0/10), (P0/10, I0). and (P0/10, I0/10). You may have to lengthen the k loop to see the full effects. Give a brief explanation of the plots.

Explanation / Answer

/*
Mega analogWrite() test

This sketch fades LEDs up and down one at a time on digital pins 2 through 13.
This sketch was written for the Arduino Mega, and will not work on previous boards.

The circuit:
* LEDs attached from pins 2 through 13 to ground.

created 8 Feb 2009
by Tom Igoe

This example code is in the public domain.

*/
// These constants won't change. They're used to give names
// to the pins used:
const int lowestPin = 2;
const int highestPin = 13;


void setup() {
  // set pins 2 through 13 as outputs:
  for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++) {
  pinMode(thisPin, OUTPUT);
  }
}

void loop() {
  // iterate over the pins:
  for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++) {
  // fade the LED on thisPin from off to brightest:
  for (int brightness = 0; brightness < 255; brightness++) {
  analogWrite(thisPin, brightness);
  delay(2);
  }
  // fade the LED on thisPin from brithstest to off:
  for (int brightness = 255; brightness >= 0; brightness--) {
  analogWrite(thisPin, brightness);
  delay(2);
  }
  // pause between LEDs:
  delay(100);
  }
}

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