Ivy's Assignment 3!

Here is an image of the circuit I had created.

Above is an image of the schematic of the circuit.

Here I explain the relationship between the variable resistor (photoresistor) and the voltage you can measure at that point.

 // These constants won't change. They're used to give names to the pins used: 

      const int analogInPin = A0;  // Analog input pin that the potentiometer is attached to 

      const int analogOutPin = 9;  // Analog output pin that the LED is attached to 

      const int analogOutPin2 = 10; //Analog output pin that the LED is attached to, two! 

      

      int sensorValue = 0;  // value read from the pot

      int outputValue = 0;  // value output to the PWM (analog out)

      int outputValue2 = 255; // value output to the PWM (analog out)

      

      int sensorMin = 1023;  // minimum sensor value

      int sensorMax = 0;     // maximum sensor value

      

      void setup() {

        // calibrate during the first five seconds

        while (millis() < 5000) {

          sensorValue = analogRead(analogInPin);

          

          // record the maximum sensor value

          if (sensorValue > sensorMax) {

            sensorMax = sensorValue;

          }

          // record the minimum sensor value

          if (sensorValue < sensorMin) {

            sensorMin = sensorValue;

          }

        }

        // initialize serial communications at 9600 bps:

        Serial.begin(9600);

      }

      

      void loop() {

        // read the analog in value:

        sensorValue = analogRead(analogInPin);

        sensorValue = constrain(sensorValue, sensorMin, sensorMax);

        // map it to the range of the analog out:

        outputValue = map(sensorValue, sensorMin, sensorMax, 0, 255);

        // map it to the range of the analog out, but with an inverse relationship

        outputValue2 = map(sensorValue, sensorMin, sensorMax, 255, 0);

        

        // change the analog out value:

        if(outputValue < 15) { //checks that light levels of the photoresistor

          analogWrite(analogOutPin, 0); // sets analogOutPin to 0 if under a certain amount of light, which turns off an LED

          analogWrite(analogOutPin2, 255); // sets analogOutPin2 to 255 if under a certain amount of light, which turns on an LED completely

        } else { // if over a certain amount of light

          analogWrite(analogOutPin, outputValue); // sets analogOutPin in accordance to the amount of light the photoresistor detects. If more light, the more it lights up.

          analogWrite(analogOutPin2, outputValue2); // sets analogOutPin2 in inverse to the amount of light the photoresistor detects. If more light, the more it gets.

        }

        

        // print the values of sensorValue, outputValue, and outputValue2 to the Serial Monitor:

        Serial.print("sensor = "); //prints "sensor"
 
        Serial.print(sensorValue); //prints out the value that the photoresistor senses

        Serial.print("\t output = "); //prints out "output"

        Serial.println(outputValue); //prints out the original mapped value

        Serial.print("\t output2 = "); //prints out "output2"

        Serial.println(outputValue2);

        

        // wait 100 milliseconds before the next loop for the analog-to-digital

        // converter to settle after the last reading:

        delay(100);

      }

Additional Questions

In your voltage divider, can the variable resistor be either R1 or R2 or does it need to be one or the other? Justify your answer with example calculations.

Yes. The code won't work as expected, but it is something you can work around easily. Below is my work.

Draw a graph where the x-axis is time and the y-axis is voltage. Plot the voltage at V-measure of your voltage divider of your shared gif.

This graph is based off of the serial numbers below for sensorValue specifically.

AnalogWrite and analogRead are respectively 8-bit and 10-bit values. Imagine you had 10-bit PWM and a 16-bit analog-to-digital converter instead. How would this change your map() code? Explain your answer.

If we had a 10-bit PWM and we had to read a 8-bit value, I would map it from 0 - 255 to 0 - 1023. If we had a 16-bit PWM and we had to read a 10-bit value, I would map it from 0 - 1023 to 0 - 65535. This is based on how binary works. The max val of n-bit integer is (2^n)-1. When n = 10, (2^10)-1 = 1023. When n = 16, (2^16)-1 = 65535.