3. Zoetrope

Introduction

In this project, we aim to create a device called a Zootropio, capable of giving the illusion of movement through a sequence of images. To make the project more engaging, we will use a motor, a switch to control the direction, another switch to turn it on and off, and a potentiometer for speed control.
To enable the carousel to rotate in one direction only, we will introduce H-Bridges.

Bridge H

H-Bridges are known as integrated circuits (ICs). Integrated circuits are components that contain complex circuits within a very small space. You can access the integrated circuit through the pins that extend from the sides.

Necessary components

• H-Bridge
• 10 kilo-ohm resistor
• Motor
• Push button
• 9V battery
• Potentiometer
• Battery holder

Construction

1. Connect the power and ground to one side of the breadboard.
2. Add 2 push buttons to the breadboard, connecting each one to a 10 kilo-ohm resistor with the other end of the resistor connected to ground. The button on pin 4 controls the direction, while the other button turns the motor on and off.
3. Connect the potentiometer to the breadboard. Connect 5 volts to one side and ground to the other side. Finally, connect the center pin to Arduino's analog input 0.
4. Place the H-Bridge on the breadboard. Connect pin 1 of the H-Bridge to Arduino's digital pin 9. This pin controls the motor; applying 5 volts turns it on, while 0 volts turns it off, enabling pulse-width modulation for speed control.
5. Connect pin 2 of the H-Bridge to Arduino's digital pin 3, and pin 7 to digital pin 2. These pins communicate with the H-Bridge to specify the direction of rotation.
6. The H-Bridge is powered from pin 16; connect it to 5 volts, and pins 4 and 5 should be connected to ground.
7. Connect the motor to pins 3 and 6 of the H-Bridge.
8. Connect pin 8 of the H-Bridge to the positive terminal of the battery.

Code explanation

const int controlPin1 = 2;
const int controlPin2 = 3;
const int enablePin = 9;
const int directionSwitchPin = 4;
const int onOffSwitchStateSwitchPin = 5;
const int potPin = A0;

int onOffSwitchState = 0;
int previousOnOffSwitchState = 0;
int directionSwitchState = 0;
int previousDirectionSwitchState = 0;

int motorEnabled = 0;
int motorSpeed = 0;
int motorDirection = 1;

void setup() {

  pinMode(directionSwitchPin, INPUT);
  pinMode(onOffSwitchStateSwitchPin, INPUT);
  pinMode(controlPin1, OUTPUT);
  pinMode(controlPin2, OUTPUT);
  pinMode(enablePin, OUTPUT);
  digitalWrite(enablePin, LOW);
  
}

void loop() {

  onOffSwitchState = digitalRead(onOffSwitchStateSwitchPin);
  delay(1);
  directionSwitchState = digitalRead(directionSwitchPin);
  motorSpeed = analogRead(potPin)/4;

  if(onOffSwitchState != previousOnOffSwitchState){
    if(onOffSwitchState == HIGH){
      motorEnabled = !motorEnabled;
    }
  }

  if(directionSwitchState != previousDirectionSwitchState){
    if(directionSwitchState == HIGH){
      motorDirection = !motorDirection;
    }
  }

  if(motorDirection == 1){
    digitalWrite(controlPin1, HIGH);
    digitalWrite(controlPin2, LOW);
  }else{
    digitalWrite(controlPin1, LOW);
    digitalWrite(controlPin2, HIGH);
  }

  if(motorEnabled == 1){
    analogWrite(enablePin, motorSpeed);
  }else{
    analogWrite(enablePin, 0);
  }

  previousDirectionSwitchState = directionSwitchState;
  previousOnOffSwitchState = onOffSwitchState;

}

Declared Variables:

• controlPin1, controlPin2, enablePin: These variables define the control pins of the H-Bridge and the enable pin (for PWM control of the motor speed).

• directionSwitchPin, onOffSwitchStateSwitchPin: These variables define the pins to which switches are connected to control the motor direction and motor on/off functionality.

• potPin: This variable defines the pin to which the potentiometer is connected to adjust the motor speed.

• Other variables like onOffSwitchState, previousOnOffSwitchState, directionSwitchState, previousDirectionSwitchState, motorEnabled, motorSpeed, motorDirection are used to store switch states and control motor behavior.

setup() Function:

• pinMode(): Configures the pins as either inputs or outputs required for H-Bridge and switch operation. The control pins (controlPin1, controlPin2, enablePin) are set as outputs to control the H-Bridge. The switches (directionSwitchPin, onOffSwitchStateSwitchPin) are set as inputs to read switch states.

• digitalWrite(enablePin, LOW): Initially sets the enable pin (enablePin) to LOW to disable the motor at startup.

loop() Function:

• Reads the state of switches and potentiometer on each iteration of the loop.

• digitalRead(): Reads the state of switches (onOffSwitchStateSwitchPin, directionSwitchPin) and saves the current state into variables (onOffSwitchState, directionSwitchState).

• analogRead(potPin): Reads the analog value from the potentiometer (potPin) and converts it to a value ranging from 0 to 1023. This value is then used to set the motorSpeed variable controlling the motor speed.

• Handles switch state changes:

  • If the on/off switch (onOffSwitchStateSwitchPin) is pressed, toggles the motorEnabled state (turns the motor on/off).
  • If the direction switch (directionSwitchPin) is pressed, toggles the motorDirection state (changes the motor direction).

• Controls the motor direction based on the motorDirection state. If motorDirection is equal to 1, the motor spins forward; otherwise, it spins backward.

• Controls motor activation and speed:

  • If motorEnabled is equal to 1 (motor is on), uses analogWrite(enablePin, motorSpeed) to activate the motor at the current speed (motorSpeed).
  • If motorEnabled is equal to 0 (motor is off), sets analogWrite(enablePin, 0) to turn off the motor.

• Updates the previous switch values for the next cycle (previousOnOffSwitchState, previousDirectionSwitchState).

In summary, this code allows control of a motor using Arduino, enabling the user to adjust motor direction and speed using switches and a potentiometer.