Cheapest Arduino based robot: parts, examples of use and documentation

This entry is part 3 of 5 in the series Cheapest robot (Arduino)
Ultrasonic Smart Car Kit

Ultrasonic Smart Car Kit

Arduino cheap robot car

Arduino cheap robot car

Funduino Arduino DuemilaNove clon

Funduino Arduino DuemilaNove clon

It’s really cheap but it does not include any documentation; but don’t panic, all you will need can be found on Internet. And now, the main electronic components: the microcontroller, the dual motor driver, the ultrasonic sensor and the servo:

The microcontroller brain is a Funduino (Arduino Duemilanove clone), and as far I’ve used it (and as other buyer said is fully, at least for software, compatible). Here we will not have any problem because there are a lot of documentation about Arduino and Duemilanove.

A simple hello world example (here the file)

// Blinking LED

int ledPin = 13;                 // LED connected to digital pin 13

void setup()
{
  Serial.begin(57600);
  printf ("Setup/n/l");
  Serial.println("Hello world!");
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  printf ("2009");
  Serial.println("2009");
  digitalWrite(ledPin, HIGH);   // sets the LED on
  delay(1000);                  // waits for a second
  digitalWrite(ledPin, LOW);    // sets the LED off
  delay(1000);                  // waits for a second
}
Dual_H-Bridge_Motor_Driver

Dual_H-Bridge_Motor_Driver

But to control the two motors this kit use an Dual H-Bridge motor driver (L298). Here (read the Drive Two DC Motors section) you can find a lot of useful documentation and examples, and  here and here you can find also more information, specially about electronics.

Here a file with a simple example, and here another example with speed control

int ENA=5;//connected to Arduino's port 5(output pwm)
int IN1=2;//connected to Arduino's port 2
int IN2=3;//connected to Arduino's port 3
int ENB=6;//connected to Arduino's port 6(output pwm)
int IN3=4;//connected to Arduino's port 4
int IN4=7;//connected to Arduino's port 7

int ledPin = 13;

void blink(int times)
{  
  while (times>0)
  {
    digitalWrite(ledPin, HIGH);   // sets the LED on
    delay(500);                  // waits for a second
    digitalWrite(ledPin, LOW);    // sets the LED off
    delay(500);
    times--;
  }
}

void initialize()
{
  Serial.println("Two motors");

  pinMode(ENA,OUTPUT);
  pinMode(ENB,OUTPUT);
  pinMode(IN1,OUTPUT);
  pinMode(IN2,OUTPUT);
  pinMode(IN3,OUTPUT);
  pinMode(IN4,OUTPUT);

  digitalWrite(ENA,LOW);
  digitalWrite(ENB,LOW);//stop motors

  digitalWrite(IN1,HIGH);
  digitalWrite(IN2,LOW);//setting motorA's forward directon
  digitalWrite(IN3,HIGH);
  digitalWrite(IN4,LOW);//setting motorB's forward directon
}

void setup()
{
  Serial.begin(57600);
  initialize();
}

void loop()
{
  int t=1;
  initialize();

  Serial.println("1 Full forward");
  analogWrite(ENA,255);//start driving motorA
  analogWrite(ENB,255);//start driving motorB

  delay(1000*t);

  Serial.println("2.1 Turning A");

  // Backwards motor A, turning robot
  digitalWrite(IN1,LOW);
  digitalWrite(IN2,HIGH);// setting motorA's backwards directon

  delay(500*t);

  // full forward again
  digitalWrite(IN1,HIGH);
  digitalWrite(IN2,LOW);//setting motorA's forward directon

  delay (1000*t);

  Serial.println("2.2 Turning B");

  // Backwards motor B, turning robot
  digitalWrite(IN3,LOW);
  digitalWrite(IN4,HIGH);//setting motorB's backward directon

  delay(500*t);

  // full forward again
  digitalWrite(IN3,HIGH);
  digitalWrite(IN4,LOW);//setting motorB's forward directon

  delay (1000*t);

  Serial.println("3 Full backward");
  // full backwards
  digitalWrite(IN1,LOW);
  digitalWrite(IN2,HIGH);// setting motorA's backwards directon

  digitalWrite(IN3,LOW);
  digitalWrite(IN4,HIGH);//setting motorB's backward directon

  delay (2000*t);
  // Slowing motors

  Serial.println("4 slowing motors");
  analogWrite (ENA,180);
  analogWrite (ENB,180);
  delay(1000*t);

  Serial.println("5 more slowing motors");
  analogWrite (ENA,110);//stop driving motorA
  analogWrite (ENB,110);//stop driving motorB
  delay(1000*t);

  Serial.println("6 stoping motors");
  analogWrite (ENA,0);//stop driving motorA
  analogWrite (ENB,0);//stop driving motorB

  blink (3);
Ultrasonic sensor hc-sr04

Ultrasonic sensor hc-sr04

The HC-SR04 ultrasonic distance sensor, example of use (here the file):

/*
HC-SR04 Ping distance sensor]
VCC to arduino 5v GND to arduino GND
Echo to Arduino pin 13 Trig to Arduino pin 12
More info at: http://goo.gl/kJ8Gl
*/

#define trigPin 9
#define echoPin 11

void setup() {
  Serial.begin (115200);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  int duration, distance;

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(1000);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;
  if (distance > 400 || distance < 0){
    Serial.println("Out of range");
  }
  else {
    Serial.print(distance);
    Serial.println(" cm");
  }

  delay(500);
}

TowerPro micro servo SG90

TowerPro micro servo SG90

And the Tower PRO SG-90 micro servo (and here the file with the example):

// Sweep
// by BARRAGAN <http://barraganstudio.com>
// This example code is in the public domain.

#include

Servo myservo;  // create servo object to control a servo
// a maximum of eight servo objects can be created

int pos = 0;    // variable to store the servo position

void setup()
{
  myservo.attach(3);  // attaches the servo on pin 3 to the servo object
}

void loop()
{
  // goes from 0 degrees to 180 degrees in steps of 1 degree 
  for(pos = 0; pos < 180; pos += 1) {
    myservo.write(pos); // tell servo to go to position in variable 'pos' 
    delay(15); // waits 15ms for the servo to reach the position 
  } 

  for(pos = 180; pos>=1; pos-=1)     // goes from 180 degrees to 0 degrees
  {
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(15);                       // waits 15ms for the servo to reach the position
  }
}

Soon I will add an LCD display with 6 buttons

Series Navigation<< Cheapest robotic platform: Smart carArduino LCD 1602 (16×2) display >>

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