Assignment 3: Input Output!

Left: A short gif of the LEDs reacting and indicating changing lower light levels as I cover and uncover the photosensor with my finger.
Right: Console output showing the original/mapped sensor values and the number of LEDs being lit.

Images:

Code:

        // Indicates current brightness, as detected by a photoresistor, on a scale of 0-3 represented
        // by three LEDs. Also prints values and LED status to the monitor.
        // Uses code from the Arduino "Analog Input" and "Calibration" built-in examples.

        const int analogInPin = A0; // Selects the analog in pin used
        const int lowLed = 4; // Identifies the low signal LED
        const int medLed = 5; // Identifies the medium signal LED
        const int hiLed = 6; // Identifies the high signal LED
        int sensorVal = 0;  // Initial sensor value
        int minVal = 1023; // Initial minimum sensor value
        int maxVal = 0; // Initial max sensor value
        int mapVal = 0; // Initial mapped sensor value

        void setup() {
          pinMode(lowLed, OUTPUT); // Sets the low signal LED pin to output
          pinMode(medLed, OUTPUT); // Sets up the medium signal LED pin to output
          pinMode(hiLed, OUTPUT); // Sets up the high signal LED pin to output
          Serial.begin(9600); // Sets up serial for output text
          while (millis() < 5000) { // 5-second calibration period
            sensorVal = analogRead(analogInPin); // Sensor value reads from pin A0
            if (sensorVal > maxVal) { // Identifies the highest value
              maxVal = sensorVal; // Sets the max value to the new highest
            }
            if (sensorVal < minVal) { // Identifies the lowest value
              minVal = sensorVal; // Sets the min value to the new lowest
            }
          }
        }

        void loop() {
          sensorVal = analogRead(analogInPin); // Sensor value reads from pin A0
          sensorVal = constrain(sensorVal, minVal, maxVal); // Constrains values based on calibration
          mapVal = map(sensorVal, minVal, maxVal, 0, 255); // Maps values to 8-bit (256 units)
          Serial.print("Sensor value: "); // Print sensor value text
          Serial.print(sensorVal); // Print the value
          Serial.print("\t Map value: "); // Print mapped value text
          Serial.print(mapVal); // Print the value
          if (mapVal <= 63) { // Bottom 1/4 of values
            digitalWrite(lowLed, LOW); // Low LED off
            digitalWrite(medLed, LOW); // Medium LED off
            digitalWrite(hiLed, LOW); // High LED off
            Serial.println("\t Lighting no LEDs!"); // Indicate no LEDs lit
          } else if (mapVal > 63 && mapVal <= 127) { // Lower middle quadrant of values
            digitalWrite(lowLed, HIGH); // Low LED on
            digitalWrite(medLed, LOW); // Medium LED off
            digitalWrite(hiLed, LOW); // High LED off
            Serial.println("\t Lighting 1 LED!"); // Indicate one LEDs lit
          } else if (mapVal > 127 && mapVal <= 191) { // Upper middle quadrant of values
            digitalWrite(lowLed, HIGH); // Low LED on
            digitalWrite(medLed, HIGH); // Medium LED on
            digitalWrite(hiLed, LOW); // High LED off
            Serial.println("\t Lighting 2 LEDs!"); // Indicate two LEDs lit
          } else { // Upper quadrant of values
            digitalWrite(lowLed, HIGH); // Low LED on
            digitalWrite(medLed, HIGH); // Medium LED on
            digitalWrite(hiLed, HIGH); // High LED on
            Serial.println("\t Lighting 3 LEDs!"); // Indicate all LEDs lit
          }
        }
      

Responses:

2. Graph: This graph is idealized with a perfectly even change in resistance and a full 5V change, but otherwise represents the voltage being measured at the voltage divider in the example gif. When I covered up the photoresistor, the resistance increased and voltage decreased.

3. Changing the PWM and analog-to-digital converter to 10- and 16-bit, respectively, would mean that I would have to change the mapped value from 0-255 to 0-1023 (2¹⁰). While the code I used is able to calibrate to the environmental light levels, I would also need to change the starting minimum value to 65535 (2¹⁶) to account for the higher possible max 16-bit values.