Introduction: Distance Meter

Picture of Distance Meter

The distance meter is a cheap and efficient gadget that allows you to measure the distance to an object. Simple and fun to build! Let’s build it.

Step 1: Step 1. Components and Tools

The components listed are replaceable depending on your preferences.
  1. 16 LEDs (different colors - I used blue, orange, yellow and red)
  2. 16 100 Ω Resistors (their values are dependent on the type of LEDs)
  3. 2 M74HC595B chips – 8-bit shift registers with an output latch pin
  4. 1 HC-SR04 –an ultrasonic sensor
  5. 1 Beeper (or any melodic speaker preferably 8-ohm)
  6. Connection wires (different colors preferred)
  7. Soldering Iron and gun
  8. Perforated circuit board (15cm x 6cm)
  9. Microcontroller chip (I used an ATMEGA 328p on an Arduino Uno board)
  10. 2 16-pin DIP sockets [optional but recommended]

Step 2: Step 2. How It Works

Picture of Step 2. How It Works

When powered, the ultrasonic measures the distance, which is translated into a series of ON LEDs. The closer the object is to the sensor the more LEDs are lit.

Step 3: Step 3. Soldering

Picture of Step 3. Soldering

Run your LEDs on the edge of the circuit board starting depending on the colors. Clip the terminals and solder the negative terminals to a common ground. Plug your resistors and solder the positive terminals of the LEDs to the resistors.

Next, if you’re using DIP sockets (recommended), plug and solder them at considerable distances from the resistors. **(For an explanation on the functionality of shift registers and how they are cascaded check online www.bildr.org/2011/02/74hc595)

Solder the HC-SR04 Ultrasonic sensor at the edge of the perforated board. Connect the melodic speaker and solder the common to ground.

Step 4: Step 4. Programming the Meter

Picture of Step 4. Programming the Meter

The following is a code listing on an Arduino IDE
/*
** Created by: Charles Muchene
** @charlesmuchene
**
** Date: 3rd October 2013
**
** Time: 1412hrs
**
** Distance meter code
** The system measures the distance
** using HC-SR04 ultrasonic sensor
** and translates it into a series
** of lit LEDs
**
** Have fun and tweak it!
*/
/* Library for the melodic pitches
** It describes the frequencies to be produced*/
#include "pitches.h"

const int triggerPin = 10; //trigger pin (green)
const int echoPin = 9; //echo pin (orange)
const int tonePin = 8; //tone pin (whilte-blue)
const int serialDataPin = 7; //serial data pin (orange)
const int registerClockPin = 6; //register clock pin (brown)
const int shiftRegisterClockPin = 5; //shift register clock
const int numOfRegisters = 16; //number of registers

const boolean registers[numOfRegisters]; //register array
int litLEDs = 0; //led pin counter
int range = 100; //range value
int distance; //distance

const int count = range / numOfRegisters; // (meters per LED)

// start up melody
int melody[] = {NOTE_C4, NOTE_G3, NOTE_G3, NOTE_A3, NOTE_G3, 0, NOTE_B3, NOTE_C4, NOTE_DS8, NOTE_DS8};

// critical distance melody
int criticalMelody[] = {NOTE_DS8, NOTE_DS8, NOTE_DS8, NOTE_DS8};

// note durations: 4 = quarter note, 8 = eighth note, etc.
int noteDurations[] = {4, 8, 8, 4, 4, 4, 4, 4, 4, 2};
int criticalNoteDurations[] = {4, 4, 4, 4};


void setup()
{
/*Pin configurations*/
pinMode(triggerPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(serialDataPin, OUTPUT);
pinMode(registerClockPin, OUTPUT);
pinMode(shiftRegisterClockPin, OUTPUT);

/*Light 'em up*/
lightEmUp();

/*Start melody*/
playMelody();

/*Turn off all LEDs*/
clearRegisters();

} // setup

/*Get distance from HC-SR04*/
int getDistance()
{
digitalWrite(triggerPin, LOW);
delayMicroseconds(2);
/*Send trigger signal*/
digitalWrite(triggerPin, HIGH);
delayMicroseconds(10);
digitalWrite(triggerPin, LOW);

/*return distance in centimeters*/
return (pulseIn(echoPin, HIGH) / 2) / 29.1;
} //get distance

//light all leds
void lightEmUp()
{
for (int pin = 0; pin < numOfRegisters; pin++)
registers[pin] = HIGH;

writeRegisters();
} //light 'em up

//set all register pins to LOW
void clearRegisters()
{
for(int i = numOfRegisters - 1; i >= 0; i--)
registers[i] = LOW;
writeRegisters();
} //clear registers
/*Write register values and store them*/
void writeRegisters()
{
/*With register clock pin set low
**the contents of the storage register
**are not changed by the changing shift register values
**/
digitalWrite(registerClockPin, LOW);

/*Loop through all the registers*/
for(int i = numOfRegisters - 1; i >= 0; i--)
{
digitalWrite(shiftRegisterClockPin, LOW);
int val = registers[i];
digitalWrite(serialDataPin, val);
digitalWrite(shiftRegisterClockPin, HIGH);
} // loops all registers

/*This signal tranfers the contents of
**of the shift register to the storage registers
*/
digitalWrite(registerClockPin, HIGH);
} //write registers

//set an individual pin HIGH or LOW
void setRegisterPin(int index, int value)
{
registers[index] = value;
} //set register pin value

/*Play start uMelody*/
void playMelody()
{
for (int thisNote = 0; thisNote < 10; thisNote++)
{
/* To calculate the note duration,
take one second divided by note type
/* e.g. quarter note = 1000 / 4,
** eighth note = 1000/8, etc */
int noteDuration = 1000/noteDurations[thisNote];
tone(tonePin, melody[thisNote], noteDuration);

/* To distinguish the notes, set a minimum time between them.
** the note's duration + 30% seems to work well */
int pauseBetweenNotes = noteDuration * 1.30;
delay(pauseBetweenNotes);
noTone(8);
} // all notes
} //play start up melody

/*Critical Melody*/
void playCriticalMelody()
{
for (int thisNote = 0; thisNote < 4; thisNote++)
{
int noteDuration = 1000/noteDurations[thisNote];

tone(tonePin, criticalMelody[thisNote], noteDuration);

/* To distinguish the notes, set a minimum time between them.
** the note's duration + 30% seems to work well*/
int pauseBetweenNotes = noteDuration * 1.30;

delay(pauseBetweenNotes);

noTone(8);

} // loop all notes

} //play critical melody

void loop()
{
/*Get distance*/
distance = getDistance();

/*Calculate the LEDs to light*/
if (range >= distance)
litLEDs = (range - distance) / count;
else
litLEDs = -1;

/*Light LEDs depending on the distance calculated*/
for (int pin = 0; pin < numOfRegisters; pin++)
{
if (pin <= litLEDs)
setRegisterPin(pin, HIGH);
else
setRegisterPin(pin, LOW);
} //for loop

writeRegisters(); // effect changes

/*Play critical proximity melody*/
if (litLEDs >= 13)
playCriticalMelody();

} //loop
/*************************************************
* “pitches.h” definition
*
* Public Constants
* The constants represent the pitch frequencies
* of the respective notes on a standard concert
* instrument tuning such as a Piano
*************************************************/
#define NOTE_B0 31
#define NOTE_C1 33
#define NOTE_CS1 35
#define NOTE_D1 37
#define NOTE_DS1 39
#define NOTE_E1 41
#define NOTE_F1 44
#define NOTE_FS1 46
#define NOTE_G1 49
#define NOTE_GS1 52
#define NOTE_A1 55
#define NOTE_AS1 58
#define NOTE_B1 62
#define NOTE_C2 65
#define NOTE_CS2 69
#define NOTE_D2 73
#define NOTE_DS2 78
#define NOTE_E2 82
#define NOTE_F2 87
#define NOTE_FS2 93
#define NOTE_G2 98
#define NOTE_GS2 104
#define NOTE_A2 110
#define NOTE_AS2 117
#define NOTE_B2 123
#define NOTE_C3 131
#define NOTE_CS3 139
#define NOTE_D3 147
#define NOTE_DS3 156
#define NOTE_E3 165
#define NOTE_F3 175
#define NOTE_FS3 185
#define NOTE_G3 196
#define NOTE_GS3 208
#define NOTE_A3 220
#define NOTE_AS3 233
#define NOTE_B3 247
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
#define NOTE_C6 1047
#define NOTE_CS6 1109
#define NOTE_D6 1175
#define NOTE_DS6 1245
#define NOTE_E6 1319
#define NOTE_F6 1397
#define NOTE_FS6 1480
#define NOTE_G6 1568
#define NOTE_GS6 1661
#define NOTE_A6 1760
#define NOTE_AS6 1865
#define NOTE_B6 1976
#define NOTE_C7 2093
#define NOTE_CS7 2217
#define NOTE_D7 2349
#define NOTE_DS7 2489
#define NOTE_E7 2637
#define NOTE_F7 2794
#define NOTE_FS7 2960
#define NOTE_G7 3136
#define NOTE_GS7 3322
#define NOTE_A7 3520
#define NOTE_AS7 3729
#define NOTE_B7 3951
#define NOTE_C8 4186
#define NOTE_CS8 4435
#define NOTE_D8 4699
#define NOTE_DS8 4978

Step 5: Schematics

Picture of Schematics

Here are schematic diagrams of the distance meter circuit and a video of how it works. Happy hacking!

Comments

Gearboxmakers (author)2013-12-03

Sure thing! just added the circuit diagrams to the last step.

Honus (author)2013-11-25

Neat! Could you possibly include a video and circuit diagram? Thanks!

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