Double Transducer: Rotation to Temperature

Indie Lee and Merlin Enriquez

Final images

Indie's double transducer that transforms a rotation angle input via potentiometer, into temperature via heatpad.

Merlin Enriquez double transducer

Detail photos

LED brightness middle step, measured by a photoresistor. (Indie)

Up close of heatpad's barrel plug (above) and LED housing (right). (Indie)

Final project movies

PXL_20260209_165023049.TS.mp4

Video documentation of Indie's double transducer. Rotation of the potentiometer translates into LED brightness, which translates into heat. The skip the middle button translates rotation of the potentiometer directly into heat, and the LED turns off.

IMG_4989.mov

Student 2 documentation video with caption, same advice and requirements as listed above.

Narrative description

When the user turns the potentiometer, the LED brightness increases. The LED is positioned in front of a photoresistor that detects the light intensity. This sensor sends data to an electric heating pad controller. As the photoresistor detects more light, the heating pad produces more heat.

Progress images

At this point, I was excited about the progress I made and thought I had finished the basic setup. Little did I know that some wires that should've been in the same row weren't, and some of my code was completely wrong! (Indie)

Middle step before soldering. Note that I switched to unhoused wires! and organize the protoboard a bit better (one ground pin, components flush against board). (Indie)

Merlin Enriquez

Discussion

Merlin:

I have a bit of experience with electronics because I took intro to arduino. At first, it was relatively easy for me to understand the basics of wiring and electronics. Since I have previous coding experience, the logic of the code felt easy for me to understand---the skills were transferable. It was still a new coding language so there are differences I had to get adjusted to. I found it easier for me to understand the connection by connecting all of the pieces together instead of testing it out one by one. Although, it helped with me writing the code, it was detrimental for me when debugging the wiring. I ran into very small, yet impactful mistakes in my wiring that costed me a lot of time and mental headache to fix. Next time, I plan to do each step little by little to fully understand the wiring.

Indie:

This was a fun introductory project to Arduino. I enjoyed the hands-on aspect of it, I really liked snapping the wires into place and the soldering step. I've never done anything like this before and it felt like solving a fun puzzle. Like Merlin, I also found the wiring part more intuitive. Although I made some wiring mistakes, working through possible wire mistakes by going component to component was a lot easier, visually and physically, than working through my coding mistakes..

One very interesting aspect of my process is that I thought I had my project up and running midway through, only to go to office hours and find some things fundamentally incorrect with my code. What happened there, I have little idea, but this is one potentially frustrating aspect of working between hardware and software that I will look out for in the future. I also had difficulty mapping the input to output values, and this is one thing I couldn't get just right. Mapping the LED brightness to the photoresistor especially was finnicky since the photoresistor was sensitive to surrounding lights in the room. Even though I made housing for the LED, I still found the mapping values a bit strange since the LED brightness wouldn't map one to one to the photoresistor input. Looking back though, I am proud of what I achieved because this is my first time using an Arduino and even using the mapping function at all! I felt accomplished when it came together, and I do think the process went as smoothly as it could've gone.

Working with new components such as the LCD screen and the heatpad was super interesting to me. At the beginning of the year when we looked through former students' projects, I was impressed with their LCD screens. Now I am glad to know that most of the code is already done by someone else and downloadable into a library so that I can easily use one myself! Using the heatpad was also interesting because it was difficult to tell if it was working or not. But honestly, the worse things worked, the better I felt when I fixed it so there's that I guess. All in all, this project was a really fun way to get into arduino and execute something functional.

Functional block diagram and electrical schematic

Code

Although Merlin and I used different types of LEDs for the middle step, we both wrote similar code in which we mapped potentiometer value to LED brightness, and LED brightness to heatpad temperature.

Project 1: Double Transducer

60-223 Intro to Physical Computing

Indie Lee

Pin mapping:

Arduino pin | role | description

-------------------------------------

A0 input potentiometer

A1 input photoresistor

6 output heatpad

8 input button

9 output LED

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

// pin assignments

const int POTPIN = A0, //white

PHOTOPIN = A1, //dark green

HEATPIN = 6, //purple

BUTTONPIN = 8, //green

LEDPIN = 9; //blue

LiquidCrystal_I2C screen(0x27, 16, 2);

const unsigned long LCD_WAIT = 500;

unsigned long lcd_timer = 0;

// input data variables

int potVal, photoVal, buttonVal;

// internal mapping values

int mappedPotVal, mappedPhotoVal;

// output variables

int ledVal, heatVal;

//LCD variables

int i, mo, mi, o;

void setup() {

pinMode(HEATPIN, OUTPUT);

pinMode(BUTTONPIN, INPUT_PULLUP);

pinMode(LEDPIN, OUTPUT);

pinMode(PHOTOPIN, INPUT);

pinMode(POTPIN, INPUT);

Serial.begin(9600);

screen.init(); //initialize the screen

screen.backlight(); //turn on backlight

}

void loop() {

// step 1: read all of the sensors

readInputs();

// step 2: make decisions about what to do

updateInternalState();

// step 3: drive all of the outputs

driveOutputs();

// step 4: report data back to the user

reportBack();

// step 5: update LCD

updateLCD();

// a brief delay at the bottom of the loop is usually a good idea

delay(5);

}

void readInputs() {

// read potentiometer

potVal = analogRead(POTPIN);

// read photoresistor

photoVal = analogRead(PHOTOPIN);

// read button

buttonVal = digitalRead(BUTTONPIN); // will be LOW when pressed

}

void updateInternalState() {

// map the potentiometer value to a range of 0 to 99

mappedPotVal = map(potVal, 0, 1023, 0, 99);

// map the photoresistor value to a range of 99 to 0

// photoresistor values are 1000 low, 50 high, map it reverse

mappedPhotoVal = map(photoVal, 50, 1000, 99, 0);

}

void driveOutputs() {

if (buttonVal == HIGH) { //button is not pressed

ledVal = map(mappedPotVal, 0, 99, 0, 255);

analogWrite(LEDPIN, ledVal);

//heatpad values are 640 low (cold), 40 high (hot)

heatVal = map(mappedPhotoVal, 0, 99, 0, 255);

analogWrite(HEATPIN, heatVal);

} else {

//button is pressed

ledVal = 0;

analogWrite(LEDPIN, ledVal);

heatVal = map(mappedPotVal, 0, 99, 0, 255);

analogWrite(HEATPIN, heatVal);

}

void updateLCD() {

unsigned long cur_time = millis();

if ((cur_time - lcd_timer) >= LCD_WAIT) {

screen.setCursor(0, 0);

screen.print("i:");

i = mappedPotVal;

screen.print(i);

screen.setCursor(6, 0);

screen.print("m:");

mo = map(ledVal, 0, 255, 0, 99);

screen.print(mo);

screen.setCursor(8, 1);

mi = mappedPhotoVal;

screen.print(mi);

screen.setCursor(12, 1);

screen.print("o:");

o = map(heatVal, 0, 255, 0, 99);

o = constrain(o, 0, 99);

screen.print(o);

lcd_timer = cur_time;

}

void reportBack() {

Serial.print("potVal = ");

Serial.print(potVal);

Serial.print(", ledVal = ");

Serial.print(ledVal);

Serial.print(", photoVal = ");

Serial.print(photoVal);

Serial.print(", heatVal = ");

Serial.println(heatVal);

}

// Project 1: Double Transducer

// 60-223 Intro to Physical Computing

// Merlin Enriquez

// button = button(input) (skip middle button)

// pot = potentiometer (input) (first)

// photo = photoresister (input)

// ledring = NeoPixel LED (output) (middle)

// heat = eletric heating pad(output) (final)

// lcd = LCD screen (output)

#include <Adafruit_NeoPixel.h>

#include <LiquidCrystal_I2C.h>

#define LED_COUNT 12 // amt of led bulbs

#define LEDRING_PIN 3 // wire clr = white

LiquidCrystal_I2C screen(0x27, 16, 2);

Adafruit_NeoPixel ring = Adafruit_NeoPixel(LED_COUNT, LEDRING_PIN, NEO_GRB + NEO_KHZ800);

const int BUTTON_PIN = 5; // wire clr = green

const int POT_PIN = A0; // wire clr = purple

const int PHOTO_PIN = A3; // wire clr = yellow

const int HEAT_PIN = 6; // wire clr = blue

const int LCD_SDA_PIN = A4; // wire clr = orange

const int LCD_SCL_PIN = A5; // wire clr = brown

// input values

int buttonVal;

int potVal;

int photoVal;

//output values

int LcdBrightness;

int heatVal = 0;

//mapped values

int mappedNeoPixelVal;

int mappedPhotoVal;

int mappedNeoLCD; //(converts output into a 0-99)

int mappedPhotoLCD; //(converts input into a 0-99)

//controls opacity

int opacityMin;

int opacityMax;

int brightnessVal;

void setup() {

Serial.begin(9600);

pinMode(BUTTON_PIN, INPUT_PULLUP); // far leg button to ground

pinMode(POT_PIN, INPUT);

pinMode(PHOTO_PIN, INPUT);

pinMode(LEDRING_PIN, OUTPUT);

pinMode(HEAT_PIN, OUTPUT);

analogWrite(HEAT_PIN, heatVal); // converts to analog signal (0,255)

// the ring led is rgba based so im giving a min + max value

// constrain the brightness value between 0,255

opacityMin = 0;

opacityMax = 255;

brightnessVal = 0;

// brightnessVal = constrain(brightnessVal, opacityMin, opacityMax);

ring.begin();

ring.show();

// make sures all led is white

for (int i = 0; i < LED_COUNT; i++) {

ring.setPixelColor(i, ring.Color(255, 255, 255));

}

ring.show();

//lcd

screen.init();

screen.backlight();

screen.clear();

}

void loop() {

readInputs();

updateInternalState();

updateOutputs();

updateLCD();

reportBack();

delay(250);

}

void readInputs() {

photoVal = analogRead(PHOTO_PIN);

potVal = analogRead(POT_PIN);

buttonVal = digitalRead(BUTTON_PIN);

}

void updateInternalState() {

mappedNeoPixelVal = map(potVal, 0, 1023, opacityMin, opacityMax);

mappedPhotoVal = map(photoVal, 0, 1023, 0, 255);

heatVal = mappedPhotoVal;

mappedNeoLCD = map(mappedNeoPixelVal, 0, 255, 0, 99);

mappedPhotoLCD = map(mappedPhotoVal, 0, 255, 0, 99);

//if button is pressed(low)

//then the heat value switches pot val (input) directly

//to controlling eletric heating pad(output)

if (buttonVal == LOW) {

heatVal = map(potVal, 0, 1023, 0, 255);

} else {

heatVal = mappedPhotoVal;

}

void updateOutputs() {

ring.setBrightness(mappedNeoPixelVal);

//so this shows up again when pot is turned back and forth

for (int i = 0; i < LED_COUNT; i++) {

ring.setPixelColor(i, ring.Color(255, 255, 255));

}

ring.show();

analogWrite(HEAT_PIN, heatVal);

Serial.println(heatVal);

//debug neopixel

Serial.print("NeoPixel brightness set to: ");

Serial.println(mappedNeoPixelVal);

}

void updateLCD() {

static unsigned long lastUpdate = 0; // stores last update time

unsigned long currentMillis = millis();

// updates every 5 secs

if (currentMillis - lastUpdate >= 5000) {

lastUpdate = currentMillis;

screen.clear();

screen.setCursor(0, 0);

screen.print("LED:");

screen.print(mappedNeoLCD);

screen.print(" PHO:");

screen.print(mappedPhotoLCD);

screen.setCursor(0, 1);

screen.print("HEAT:");

screen.print(map(heatVal, 0, 255, 0, 99));

if (buttonVal == LOW) {

screen.print(" [BTN]");

}

void reportBack() {

//displays on serial monitor

Serial.print("photoVal = ");

Serial.print(photoVal);

Serial.print(", potVal = ");

Serial.print(potVal);

Serial.print(", buttonVal = ");

Serial.println(buttonVal);

}

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