Digital Measuring Tape

Our IoT project utilizes ultrasonic sensor technology to create a modern-day measuring tape.

IntermediateWork in progressOver 2 days1,097

Things used in this project

Hardware components

Ultrasonic Sensor - HC-SR04 (Generic)

Jumper wires (generic)

Particle Argon

Adafruit RGB Backlight LCD - 16x2

Breadboard (generic)

Light Switch

Wire, Magnet

Software apps and online services

Particle Build Web IDE

Fritzing

Hand tools and fabrication machines

Wire Stripper & Cutter, 32-20 AWG / 0.05-0.5mm² Solid & Stranded Wires

Story

Introduction

Our IoT project is, ultrasonic sensor technology, to create a modern-day measuring tape. By incorporating this sensor into a compact and portable device, we enable users to quickly and accurately measure distances in various settings. From construction sites to home renovation projects, our ultrasonic sensor-based measuring tape provides measurements without the need for bulky and cumbersome traditional measuring tools. Our device is easy to use, highly portable, and delivers reliable real-time results, allowing users to complete their projects with increased efficiency and accuracy. Whether you're a professional contractor or a DIY enthusiast, our ultrasonic sensor-based measuring tape is the perfect tool for all your measuring needs.

Ultrasonic Sensor Background

Ultrasonic sensors work by emitting high-frequency sound waves and then measuring the time it takes for those waves to bounce back after they hit an object. These sensors typically consist of a transmitter, which emits the sound waves, and a receiver, which detects the waves as they return.

When the sound waves emitted by the sensor hit an object, they bounce back to the sensor at a speed that depends on the distance between the sensor and the object. The sensor then calculates the time it takes for the sound waves to travel to the object and back, using this time to determine the distance to the object.

The accuracy of ultrasonic sensors depends on several factors, including the frequency of the sound waves, the power of the transmitter, and the sensitivity of the receiver. These sensors can be used in various applications, from measuring distances and detecting objects to monitoring fluid levels and even guiding autonomous vehicles.

Figure 1: Ultrasonic Sensor

Design

With the digital measuring tape, two separate circuits, each with a Particle Argon-Based IoT, were developed in order to construct the device. One holds the LCD Display Module with an on/off button while the other contains the ultrasonic sensor to measure distance. In essence, when the button is manually pressed the ultrasonic sensor will activate and take a measurement of the object that is directly in front of it. After taking a measurement, the Particle Argon from the circuit will communicate to the other Particle and display the measurement on the LCD Display.

Figure 2: Ultrasonic Senor Schematic

Figure 3: Ultrasonic Senor Circuit

Figure 4: Switch Schematic

Figure 5: Switch Circuit

Testing

Before assessing the actual project with the ultrasonic sensor, it is important to acknowledge the previous attempts with the project. The original plan was to create a digital measuring device with the use of a laser. With the laser, one would be able to make a measurement by allowing the light of the laser to transmit onto an object and then reflect back. The distance it takes for the laser to hit the object would be recorded and inputted into a database. The project was functioning well enabling us to have an operational laser and develop a switch to activate such functionality. To enhance the performance of the laser and have a better reception of data accuracy, a lidar sensor was purchased as recommended by Professor McAlpine. Unfortunately, the lidar sensor that was ordered came in way smaller than expected and we did not have the proper tools to connect it to the circuit. Therefore, we transitioned from the laser to the ultrasonic sensor. The functionality would be the same but a different conception of capturing distance would be the only difference between the laser and the ultrasonic sensor.

For this project, the ultrasonic sensor will face an object and be turned on by clicking the push button. When turned on the ultrasonic sensor would send out waves to hit the object and reflect back to the sensor. The distance of the reflected waves will be recorded and placed into a database. When first experimenting with the project, we tested it with several objects including a box, soda can, headphone case, etc. just to ensure that there was a consistent measurement of distance that would capture any data no matter the object in use. From there, we used a box as our measured object for distance and tested our design at different distances.

Figure 6: Ultrasonic Senor Testing

Conclusion/Analysis

From this experiment, one can confirm the use of an ultrasonic sensor for the purpose of determining distances. The measured distances may not be as accurate and precise as they could be but on the surface, they are valid measurements that are relatively close to the actual measurement. This was one of the major difficulties in the development of the digital measurement tape.

The greatest challenge of this whole project would have been coding the programs for the device to work properly. Given the regular functionality of the Particle Argon-Based Internet of Things, the experiment faced many difficulties in finding and running any proper code that would enable the Particle to measure and record distance data. Even with the plethora of resources to derive code from, it was complicated in finding commands that could produce and archive measurements. The simplest part of the project was building the circuits for the device to function; however, it was problematic determining whether the builds of circuits were correct since the code did run correctly often. The source of the issue stems from the lack of experience and knowledge of coding with Particle devices but also implementing code that could not only record distance from an ultrasonic sensor but have it communicate such data to an LCD Display. A collection of various codes were utilized in the process to compensate and bypass certain functions and commands in order to get the project going. Eventually, we learned how to use the code library and implement our own code to have certain commands work.

In the near future, there are prospective plans to enhance the overall performance of the project and have access to better equipment in order to produce a better system. Eventually, we would like to fully develop an operational digital measuring tape device that can be used in real-world applications.

Code

// This #include statement was automatically added by the Particle IDE.
#include <Grove-Ultrasonic-Ranger.h>

const int trigPin = A2;
const int echoPin = D5;
int lastSecond = 0;
float inches;
unsigned long duration;
int distanceCm, distanceInch;
Ultrasonic ultrasonic(D4);          // Ultrasonic object constructor

	long RangeInCentimeters; 
void setup()
{
	Serial.begin(9600);             // Begin serial communications
  	Particle.subscribe("status", "on", PUBLIC);
  // Set the trigger pin as an output and the echo pin as an input
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT_PULLDOWN);
}

void loop()
{
	RangeInCentimeters = ultrasonic.MeasureInCentimeters();     // Get the current distance value
	Serial.print(RangeInCentimeters);                           // Out put the value over serial
	Serial.println(" cm"); // use 'particle serial monitor --follow' in the CLI to see serial output
	  digitalWrite(trigPin, LOW);
  delay(2);
  digitalWrite(trigPin, HIGH);
  delay(10);
  digitalWrite(trigPin, LOW);
  delayMicroseconds(100);
	Particle.publish("Distance", String(inches), PUBLIC);
  Serial.print("Distance: ");
  Serial.print(inches);
  Serial.println(" inches");
	delay(1000);                     // small delay, so the sensor has some time to do it's thing
}

int switchPin = D2; // switch connected to digital pin 2
int ledPin = D4;   // LED connected to digital pin 4
float inches;
LiquidCrystal_I2C *lcd;

void setup() {
  pinMode(switchPin, INPUT); // set switch pin as input with internal pull-up resistor
  pinMode(ledPin, OUTPUT);          // set LED pin as output
   lcd = new LiquidCrystal_I2C(0x27, 16, 2);
  lcd->init();
  lcd->backlight();
  lcd->clear();
  lcd->print("Distance");
  Particle.subscribe("Distance", String(inches), PUBLIC);
}

void loop() {
    
    lcd->setCursor(0, 1);
  lcd->print("Dist: ");
  lcd->print(inches);
  lcd->print("inch");
	delay(100);
  int switchState = digitalRead(switchPin); // read switch state

  if (switchState == LOW) {    // if switch is pressed
    digitalWrite(ledPin, HIGH); // turn on LED
    Particle.publish("status", "ON",PUBLIC);  //subscribe to this mouse event.
    delay(1000);  //delay to prevent overloading the cloud communication.
  } else {                     // otherwise
    digitalWrite(ledPin, LOW);  // turn off LED
    Particle.publish("status", "OFF",PUBLIC);  //subscribe to this mouse event.
    delay(1000);  //delay to prevent overloading the cloud communication.
    
    
  }
  
}