Final images

Detail photos

Final project movies

Emily's Double Transducer Video

Magnolia's Double Transducer shown close up on the mechanical middle component

Magnolia's Double Transducer Skip the Middle Button

Narrative description

Our device begins with a sensor that detects the magnetic field from a nearby magnet. This sensor measures the magnetic strength in one direction (the Y-axis) and uses it to adjust a motor that can turn between 10 and 170 degrees. As the magnetic field changes, the motor moves an object up or down using a pulley system. A laser sensor below measures how far the object is, and this distance then determines a sound frequency: the farther the object, the higher the pitch.

Progress images

Discussion

The double transducer project was quite challenging overall, with many components not working as expected and numerous unexpected issues. Our double transducer consisted of four components that were new to us, it took us a while to make each work. Ultimately we learn a lot about Arduino-based techniques such as debugging, soldering, and breadboarding. 

Most of our components required different libraries to be downloaded and one major challenge we faced was a library conflict. Our code produced long error messages, and we initially had no idea what was wrong. We spent a lot of time troubleshooting the wiring but found out later that the problem was due to the fact that most of the libraries we used were timer-based. Running them simultaneously caused the system to crash. Fortunately, we resolved this issue by replacing some of the libraries. In the future, we would approach debugging with more consideration, ensuring that we fully understand the errors before assuming the problem is with the wiring.

In addition to coding challenges, crafting the physical setup was a significant part of the project. We have a pulley system as a middle step, which added a hands-on element to the build. Initially, our pulley had a very limited range of movement, only spanning a few centimeters. We replaced the ultrasonic sensor with a laser distance sensor to improve accuracy. However, the laser sensor’s readings were highly dependent on how well the pulley was constructed, which made it difficult to get stable data and map the values accurately.

Overall, project 1 has prepared us to work with new components and design interactive devices using Arduino more confidently. 

Functional block diagram and electrical schematic

Code

//Double Transducer: Magnetic Field to Pitch

//Emily Lau and Magnolia Luu

// Receives input from the magnetometer, and maps that to the 0-180 degree servo, the distance sensor reads the object's distance. That's then mapped to the tone of the speaker. All the maps are displayed on the LCD Display

//Pin Map:

// SDA & SCL --> 3-Axis Magnetometer, LCD Display, and Laser Distance Sensor VL53L0X

// Pin 2     --> input  --> Servo Motor

// Pin 8     --> input  --> Skip the Middle Button

// Pin 10    --> output --> Speaker

#include<Servo.h>

#include<Wire.h>

#include<LiquidCrystal_I2C.h>

#include <DFRobot_VL53L0X.h>

#include <QMC5883LCompass.h>

QMC5883LCompass Magnet;

DFRobot_VL53L0X sensor;

Servo motor;

const int motorPin = 2;

const int SPEAKER_PIN = 10;

const int BUTTON_PIN = 8;

//event timer (Taken from the course website)

//const int QUARTERWAIT = 250; // this variable, of type integer, is the number of milliseconds to wait between blinks

//unsigned long quarterTimer = 0; // this variable, of type "unsigned long," will help keep track of passing time

const unsigned long quarterSecondWait = 500;

unsigned long next_time_to_run = 0;

//unsigned long WAIT = 0; // each event loop needs a unique timer variable

LiquidCrystal_I2C screen(0x27, 16, 2);

void setup() {

  Serial.begin(115200);

  pinMode(BUTTON_PIN, INPUT);

  pinMode(SPEAKER_PIN, OUTPUT);

//Servo motor

  motor.attach(motorPin);

//magnetometer

  Magnet.init();

//distance sensor

  Wire.begin();

  sensor.begin(0x50);

  sensor.setMode(sensor.eContinuous, sensor.eHigh);

  sensor.start();

//LCD Display

  screen.init();

  screen.backlight();

  screen.home();

}

void loop() {

  //step 1: gather input

  Magnet.read(); //read Magnet

  int y = Magnet.getY();//read the Y value output from the magnetometer

  int abMField = abs(y); //magnetic field variable assigned to abs. value of y

  int sensorDist = sensor.getDistance();

  int buttonVal = digitalRead(8); //high and low for the skip the middle button

  int motorPosition = map(abMField, 30, 28000, 5, 175); //map magnetometer output to servo motor output

  unsigned int frequency = 2000;

  //Step 2: make decision do math (Compute and make decisions based on the inputs)

  if (buttonVal == LOW) { //when button is not pressed

    frequency = map(sensorDist, 35, 85, 2000, 4210); 

    tone(SPEAKER_PIN, frequency, 0); //tone based on laser distance sensor

    //Step 3: do output

    motor.write(motorPosition);

  } else { //if button is pressed

    tone(SPEAKER_PIN, abMField, 0); //tone based on magnetometer

    motorPosition = 5; //reset motor position to lowest part of its range

    motor.write(motorPosition);

  }

  //Step 4: print/report information back to the user

  //Serial.println(avMField);

  //Serial.print("Distance: ");

  //Serial.println(frequency);

  // if it has at least 250 milliseconds since the quarter-second light last changed:

  //if ( (millis() - quarterTimer) >= QUARTERWAIT ) { // millis() is always the number of milliseconds since the Arduino powered up

  if (millis() >= next_time_to_run) {

    //LCD

    screen.setCursor(0, 0);

    screen.print("I:");

    //Print Magnetometer Input

    int fieldConstrain = constrain(abMField, 30, 28000);

    screen.print(map(fieldConstrain, 30, 28000, 0, 99));

    //Print Motor Position

    screen.setCursor(5, 0);

    int motorPositionConstrain = constrain(motorPosition, 5, 175);

    screen.print("m:");

    screen.print(map(motorPositionConstrain, 5, 175, 0, 99));

    //Print Distance Sensor 

    screen.setCursor(5, 1);

    int sensorDistConstrain = constrain(sensorDist, 35, 85);

    screen.print("m:");

    screen.print(map(sensorDistConstrain, 35, 85, 0, 99));

    //Print Speaker Output

    screen.setCursor(12, 1);

    int frequencyConstrain = constrain(frequency, 2000, 4210);

    screen.print("O:");

    screen.print(map(frequencyConstrain, 2000, 4210, 0, 99));

    next_time_to_run = millis() + quarterSecondWait; // reset the timer before exiting the function.

  }

}