Source: WeChat Public Account: Wangzai Dad’s Creation Society

Figure 1

The Spring Festival is the most traditional and grand festival in China. Customs during the Spring Festival include posting couplets, setting off firecrackers, and visiting relatives and friends. Of course, the warmest moment is the family gathering for a reunion dinner and watching the Spring Festival Gala on New Year’s Eve. To celebrate the upcoming Year of the Tiger Spring Festival, Wangzai Dad has created a unique flip animation display, which I named the Page-turning display.

Figure 2 Page-turning Animation Display

Since it is a display, it must have a screen. However, this screen is not electronic but rather an old-fashioned flip type, similar to the effect of quickly flipping through a book. In fact, the videos played on screens in our lives are also a frame-by-frame switching effect, but the switching speed is very fast, and the human eye can no longer perceive it. Our flip animation display aims to restore this display principle.

Let’s first take a look at how the flip animation display works through a video.

We designed the flip animation display to resemble a retro television set, using laser cutting technology to process linden wood and acrylic sheets to create the appearance structure of the flip animation display. Figure 3 shows the effect diagram.

Figure 3 Simulation Diagram of Flip Animation Display

From the preliminary observation of the simulation diagram above, we can see that the flip animation display consists of three parts: the rotating display part, the outer frame part, and the electronic control part.

For the driving motor of the rotating display part, there are many options available, such as stepper motors, DC geared motors, and servos. Since the load of this rotating part is not very large and the speed requirement is not very high, it also needs to accurately control the rotation angle while rotating. Therefore, we chose the cost-effective 28BYJ-48 micro stepper motor, which can work with the ULN2003 driver, greatly reducing the difficulty of use and minimizing the space volume. The stepper motor is shown in Figure 4.

Figure 4 28BYJ-48 Micro Stepper Motor

After solving the key driving part, we chose the Arduino Nano as the main control board and added a Hall sensor paired with a magnet to record the number of rotations. The specific details are shown in Figure 5.

Figure 5 Internal Diagram of Flip Animation Display

Once the plan is confirmed, we can start designing the appearance structure of the flip animation display.

We used LaserMaker laser modeling software to design the blueprints.

The download method for the modeling software is shown in Figure 6.

Figure 6 Download of LaserMaker Software

After completing the installation, open the software, and the interface is shown in Figure 7.

Figure 7 LaserMaker Software Running Interface

In the LaserMaker software, we designed the retro television shape as shown in Figure 8. For the flip part used to display images, we used a 1mm thick transparent acrylic sheet, while the other structural parts were made of 3mm thick linden wood. To increase the interactivity of the work, we designed a magic wand as the start-stop switch for the flip display.

Figure 8 Design Diagram of Flip Animation Display

As for the animation stickers for the flip display, you need to search for New Year animation materials (or your favorite anime materials) online, modify them to the same size as the parts, print them out, and stick them onto the acrylic sheet.

Figure 9 Stickers and Acrylic Sheet

Figure 10 Stickers Stuck on Acrylic Sheet

After completing the blueprint design, we used a laser cutter to process it, and the cut parts are shown in Figure 11.

Figure 11 Physical Diagram of Parts After Laser Cutting

In addition to the appearance structure, this flip animation display also requires the following parts:

• Arduino Nano controller with expansion board *1

• Hall sensors *2

• 28BYJ-48 stepper motor *1

• ULN2003 stepper motor driver *1

• Switch *1

• DC power interface *1

• 3mm linden wood *1 (40cm * 60cm)

• 1mm transparent acrylic sheet *2 (40cm * 60cm)

• Dupont wires (several)

• 3mm to 5mm coupling *1

• 20cm D-axis *1

• Hardware (several)

Figure 12 Equipment List for Flip Animation Display

Once the equipment is ready, let’s see how the electronic control part is connected.

The wiring diagram for the flip animation display is shown in Figure 13.

The stepper motor connects to the controller’s digital pins 4-7, and the two Hall sensors connect to digital pins 2 and 3 respectively, with one Hall sensor serving as the start-stop switch and the other Hall sensor detecting how many circles the disk has turned.

Figure 13 Wiring Diagram of Flip Animation Display

With all preparations complete, we can start assembling the project.

The assembly of the flip animation display is not very complicated, but it still requires careful installation step by step.

Step 1: Install Electronic Components

First, we install the switch for the flip display. For this project, we chose a retro-style toggle switch, which is installed on the front wooden panel, as shown in Figures 14 and 15.

Figure 14 Installing the Toggle Switch

Figure 15 Toggle Switch Installed

Next, install the controller, stepper motor, driver, and power interface. The required parts are shown in Figure 16.

Figure 16 Electronic Components

The main control and stepper motor parts are installed as shown in Figure 17.

Figure 17 Main Control and Stepper Motor Installed

Next, install the Hall sensors used to record the number of rotations. The installation is completed as shown in Figure 18.

Figure 18 Hall Sensor Installed

Step 2: Assemble the Frame Structure

Once the electronic components are installed, the next step is to assemble the frame. The frame consists of 5 parts and can be assembled by simply fitting them into the slots.

Figure 19 Parts Needed for Frame Assembly

The frame assembly is completed as shown in Figure 20.

Figure 20 Frame Assembly Completed

After completing the frame, we need to install the rotating skeleton for the flip display. The required parts are shown in Figure 21.

Figure 21 Parts Needed for Installing Rotating Skeleton

During assembly, the D-axis needs to be installed in the rectangular box, and disks need to be installed on both sides of the box. The installation is completed as shown in Figure 22.

Figure 22 Rotating Skeleton Installed

Once the rotating skeleton is assembled, it needs to be combined with the frame, as shown in Figure 23.

Figure 23 Rotating Skeleton and Frame Combined

Using a 5mm to 3mm coupling, connect the stepper motor to the D-axis. On the other side, to ensure the flexibility of the axis during rotation, we can install a bearing in the hole position. The installation is completed as shown in Figure 24.

Figure 24 Rotating Skeleton and Frame Combination Completed

The next step is to install the front wooden panel onto the frame.

Figure 25 Front Wooden Panel and Frame Combined

Figure 26 Front Wooden Panel and Frame Combined Completed

Step 3: Install Display Parts and Others

Now, the overall effect of the “television” is taking shape. If we can add an antenna, it will be even more “soulful”. Let’s install the antenna and the magic wand for starting and stopping the “television”.

Figure 27 Parts Needed for Installing Antenna and Magic Wand

Don’t forget to put a magnet in the middle of the magic wand. The installation is completed as shown in Figure 28.

Figure 28 Antenna and Magic Wand Installed

Finally, we install the most important display image into the skeleton of the display, and the assembly of the flip animation display is complete.

Figure 29 Installing Display Image

When installing the acrylic image, align it with the holes on both sides of the disk. The completed effect of the flip animation display is shown below.

Figure 30 Display Image Installation Completed

Figure 31 Project Assembly Completed

The project assembly is complete. Next, we will write a program to give the project its soul.

This project uses Arduino IDE as the programming environment. The programming environment can be downloaded from the Arduino official website.

Figure 32

Of course, you can also download the latest Mixly graphical programming software from the mixly.org website, which integrates the Arduino IDE programming environment, saving a lot of configuration trouble.

This time, the flip animation display we made (Page-turning display) uses a stepper motor to make the flip animation display rotate, using two Hall sensors to control the animation playback and record the number of rotations. The use of the stepper motor and Hall sensors is the key to this project’s program design, and we will complete it step by step according to the programming ideas.

Figure 33 Program Design Mind Map

Background Knowledge

The Hall sensor is based on the Hall effect and can be used to detect magnetic materials (magnets).

What is the Hall effect? The Hall effect was discovered by physicist Hall in 1879. When a magnetic field approaches a conductor through which current flows, the electrons in the conductor will deflect to one side due to the influence of the magnetic field, creating a potential difference in the conductor. This is the Hall effect, which can be used to detect magnetic materials.

Common Hall sensors include switch-type Hall and linear Hall types.

Linear Hall sensors output analog signals, while switch-type Hall sensors output digital signals.

For this project, we only need to use the Hall sensor to control the start and stop of the flip animation display, so we only need a switch-type Hall sensor.

The programming method for the Hall sensor is very simple; it can detect whether the magnet is present or not.

We input the following program in the programming environment to test the status of the Hall sensor.

#define Hall_START 2 //Hall sensor pinint START;//Variable to store start statusvoid setup(){  pinMode(Hall_START, INPUT);//START  Serial.begin(9600); }void loop(){  START = digitalRead(Hall_START);//Store the status of the Hall sensor  Serial.println(START);  delay(1000);}

The program output result is shown in Figure 34.

When the magnet approaches, the signal is 0, and when the magnet is away, the signal is 1.

Figure 34 Hall Sensor Test

The same method can be used to test the second Hall sensor.

We will continue to modify the program based on the original.

#define Hall_START 2 //Hall sensor pin#define Hall_END 3 //Hall sensor pinint START;//Variable to store start statusint END;//Variable to store end statusvoid setup(){  pinMode(Hall_START, INPUT);//START  pinMode(Hall_END, INPUT);//END  Serial.begin(9600);}void loop(){  START = digitalRead(Hall_START);//Store the status of Hall sensor  END = digitalRead(Hall_END);//Store the status of the second Hall sensor  Serial.print(F("First Hall sensor status:"));  Serial.println(START);  delay(1000);  Serial.print(F("Second Hall sensor status:"));  Serial.println(END);  delay(1000);}

The effect after downloading and running the program is shown in Figure 35.

Figure 35 Testing Two Hall Sensors Simultaneously

Thus, both Hall sensors can be controlled.

Next, let’s enrich the program and set it so that when the magnet approaches the Hall sensor for more than 0.5 seconds, it starts working. The program is as follows.

#define Hall_START 2 //Hall sensor pin#define Hall_END 3 //Hall sensor pin#define OVER 1    //Determine whether to enter the final stageint START;//Variable to store start statusint END;//Variable to store end statusbool is_working = false;//Working statusbool is_free = true;//Idle statusint count=0;//Counterint SPEED=0;//speedchar MODEL;          //Modevoid setup(){  pinMode(Hall_START, INPUT);//START  pinMode(Hall_END, INPUT);//END  Serial.begin(9600);}void loop(){   if(START == 1 && digitalRead(Hall_START) == 0)//Two detections of the button status  {    delay(500);    if ( digitalRead(Hall_START) == 0 && is_free == true) //If the device is in idle state, enter working mode    {      is_free = false;      is_working = true;    }  }  START = digitalRead(Hall_START);//Store the status of Hall sensor  END = digitalRead(Hall_END);//Store the status of the second Hall sensor   //Start working  if(is_free == false && is_working == true )  {      Serial.println(F("Working"));        //Counter counts, ignore the first detection status           count++;      if(count > 500)  { MODEL = OVER; }  }  //End working  if (MODEL == OVER && END == 0)  {    Serial.println(F("End Working"));    count = 0;//Reset counter    is_working = false;//Reset working indicator variable    is_free = true;//Reset idle indicator variable    MODEL = 0;//Reset status  }}

In the program, we set two variables, “START” and “END”, to store the values of the two Hall sensors, and use two variables, “is_free” and “is_working”, to mark the working status, using the variable “MODEL” to store the working status. When a magnet approaches Hall sensor 1 and remains for more than 0.5 seconds, it enters working status, and the variable “count” starts counting. When the variable “count” exceeds 500, it ends working and resets all variable statuses.

The running result after downloading the program is shown in Figure 36. When the magnet approaches the Hall sensor for more than 0.5 seconds, counting starts, and when the counter value exceeds 500, it stops working.

Figure 36 Hall Sensor Start-Stop Test

Thus, we have achieved the function of using a magnet to control the start and stop. Next, we only need to add the program for the stepper motor rotation to achieve the actual page-turning action.

Let’s learn how to control the stepper motor.

Background Knowledge

The stepper motor we chose this time is the 28BYJ-48 stepper motor, which is formally named the permanent magnet unipolar four-phase stepper motor. Such a complex name can be a bit daunting.

First, let’s take a look at the origin of the name 28BYJ-48 stepper motor.

• 28: The effective maximum outer diameter of the stepper motor is 28mm.

• B: Indicates that it is a stepper motor.

• Y: Indicates that it is a permanent magnet type.

• J: Indicates that it is a geared type (gear ratio 1:64).

• 48: Indicates four-phase eight-step.

In other words, the meaning of 28BYJ-48 is a 28mm outer diameter four-phase eight-step permanent magnet geared stepper motor. Isn’t it a bit confusing? Don’t worry, we will look at it step by step.

Typically, a motor consists of a stator and a rotor. Each tooth of the rotor carries a permanent magnet, which is the concept of a permanent magnet type.

The stator is on the outer ring, and there are 8 teeth on the stator, each wound with a coil, two at a time, creating 4 phases, which is the concept of four phases. As for the eight steps, we won’t go into detail here; you can simply understand it as the power-on sequence of the four groups of coils.

Next, let’s explain the concept of gearing in the name. Figure 37 shows the disassembly diagram of the 28BYJ-48 stepper motor.

Figure 37 Internal Diagram of 28BYJ-48 Stepper Motor

From the diagram, we can see that the small white gear in the center is the rotor shaft of the stepper motor, which drives a large gear for one level of reduction. The motor shown in the figure has a total of 4 levels of reduction. So what is the total gear ratio? That is, how many times must the rotor turn for the output shaft to turn once?

Looking back at the gear ratio parameter in the motor specifications, it is 1:64. That is, the rotor must turn 64 times for the output shaft to turn once. No matter which manufacturer produces the motor, as long as the model is 28BYJ-48, the specified gear ratio is always 1:64.

We will stop here for the basic control principle introduction.

Figure 38 Illustration of Stepper Motor Gear Ratio

In fact, controlling a stepper motor with just a controller is quite difficult; a driver is needed to drive the stepper motor. The ULN2003 driver is a good companion for the 28BYJ-48 stepper motor and usually appears together.

After becoming familiar with the 28BYJ-48 stepper motor, let’s write a program to control the stepper motor. We can choose either the built-in 【Stepper】 library in Arduino IDE or the 【AccelStepper】 third-party library.

Since the built-in 【Stepper】 library in Arduino does not allow other programs to run while controlling the stepper motor, we need the simple, easy-to-use, and powerful 【AccelStepper】 third-party library, allowing Arduino to control the stepper motor while completing other tasks.

Installing the AccelStepper Library

In the Arduino IDE programming environment, click on the 【Library Management】 option in the Tools menu, enter 【AccelStepper】 in the input box, and click install, as shown in Figure 39.

Figure 39 Installing AccelStepper Library

Once installed, you can use this library to control the stepper motor.

We input the following program in the programming environment.

#include "AccelStepper.h"// Motor step mode definition#define FULLSTEP 4    //Full step parameter#define HALFSTEP 8    //Half step parameter// Define stepper motor pins#define motor1Pin1  4     // Pin in1 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin2  5     // Pin in2 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin3  6    // Pin in3 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin4  7    // Pin in4 connected to ULN2003 motor driver for 28BYJ48// Define stepper motor object// The order of ULN2003 driver pins is in1-in3-in2-in4// The motor is set to run in full step modeAccelStepper stepper(FULLSTEP, motor1Pin1, motor1Pin3, motor1Pin2, motor1Pin4);void setup(){  stepper.setMaxSpeed(500.0);    // Maximum speed of 500  stepper.setAcceleration(50.0);  // Acceleration of 50.0  Serial.begin(9600); }void loop(){  if ( stepper.currentPosition() == 0 )  {    // Motor rotates one circle    stepper.moveTo(2048);                 }   else if ( stepper.currentPosition() == 2048 )  {    // Motor rotates one circle    stepper.moveTo(0);             }           stepper.run();   // Motor runs}

In the program, we set the maximum running speed of the stepper motor using 【setMaxSpeed】 and set the acceleration using 【setAcceleration】. The 【currentPosition】 function retrieves the current position of the stepper motor, and the 【moveTo】 command sets the absolute target position for the stepper motor, which is to rotate to a specified angle. When the stepper motor is powered on, its position is 0.

After running the program, we will see that the stepper motor rotates one circle and then stops. Why is stepper.moveTo(2048) one rotation? The 2048 here refers to the number of steps required for the output shaft to rotate once.

The step angle of the four-phase eight-step stepper motor is 11.25°. To complete one rotation, the rotor needs to take 360/11.25=32 steps. With a gear ratio of 1:64, the output shaft requires 32*64=2048 steps to complete one rotation.

Moreover, the 【AccelStepper】 library also provides some other commonly used functions, as follows.

Common Functions and Operations

• setCurrentPosition – Reset the initial position of the stepper motor.

Using the setCurrentPosition function allows you to modify the current position value. For example, if the stepper motor is currently at position 0, inputting stepper.setCurrentPosition(512) will change the original position from 0 to 512.

Figure 40 Illustration of setCurrentPosition Function

• move – Set the relative target position for the stepper motor to move.

stepper.move(1024); // The move function can make the stepper motor run the corresponding number of steps.

For example, if the stepper motor is currently at position 0, move(512) will make it turn 512 steps to position 512. Another move(512) command will make it point to position 1024.

Figure 41 Illustration of move Function

• moveTo – Set the absolute target position for the stepper motor to move.

The moveTo command can make the stepper motor rotate to a specified angle. For example, moveTo(1024) will make the stepper motor point to position 1024. If you input moveTo(1024) again, the stepper motor will not move since it is already at position 1024.

Figure 42 Illustration of moveTo Function

• runToNewPosition – Make the motor run to the user-specified position value, with the target position being absolute.

stepper.runToNewPosition(2048); // Using runToNewPosition function to make the motor run to the user-specified position value.

The runToNewPosition command is similar to the previous moveTo command, but the runToNewPosition command will not execute subsequent program content until the stepper motor reaches the target position.

Figure 43 Illustration of runToNewPosition Function

• setSpeed – Set the running speed of the stepper motor.

• run – Stepper motor runs (acceleration and deceleration mode).

• runSpeed – Stepper motor runs (constant speed mode).

If you want the stepper motor to rotate at a constant speed, you need to use setSpeed to set the running speed of the stepper motor and the runSpeed() function.

For example, inputting the following two lines of code will make the stepper motor run at a constant speed of 300.

stepper.setSpeed(300);  // Initialize motor speed to 300stepper.runSpeed();

The above is an introduction to the commonly used functions of the AccelStepper library (here we reference the materials provided by the Taiji Maker Team, and we thank Taiji Maker for their contributions to the maker community). There are many other functions not listed here in the AccelStepper library. We believe that once you master the above functions, it will be easier to understand and master the other functions of the AccelStepper library. If you need more information on using the AccelStepper library, you can find it on the AirSpayce official website.

In this flip animation display, we just need the stepper motor to run at a constant speed.

We will combine the program for the Hall sensor with the stepper motor program to complete the program control for the flip animation display.

The complete program is as follows:

#include "AccelStepper.h"// Motor step mode definition#define FULLSTEP 4    //Full step parameter#define HALFSTEP 8    //Half step parameter// Define stepper motor pins#define motor1Pin1  4     // Pin in1 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin2  5     // Pin in2 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin3  6    // Pin in3 connected to ULN2003 motor driver for 28BYJ48#define motor1Pin4  7    // Pin in4 connected to ULN2003 motor driver for 28BYJ48#define Hall_START 2 //Hall sensor pin#define Hall_END 3 //Hall sensor pin#define OVER 1    //Determine whether to enter the final stage// Define stepper motor object// The order of ULN2003 driver pins is in1-in3-in2-in4// The motor is set to run in full step modeAccelStepper stepper(FULLSTEP, motor1Pin1, motor1Pin3, motor1Pin2, motor1Pin4);int START;//Variable to store start statusint END;//Variable to store end statusbool is_working = false;//Working statusbool is_free = true;//Idle statusint count=0;//Counterint SPEED=0;//speedchar MODEL;          //Modevoid setup(){  pinMode(Hall_START, INPUT);//START  pinMode(Hall_END, INPUT);//END  stepper.setMaxSpeed(500.0);    // Maximum speed of 500  stepper.setSpeed(0);      // Initialize motor speed to 0  Serial.begin(9600);  //Reset to initial position  while(digitalRead(Hall_END) == 1)  {    stepper.setSpeed(100);    stepper.runSpeed();  }  stepper.setSpeed(0);  stepper.runSpeed(); }void loop(){  if(START == 1 && digitalRead(Hall_START) == 0)//Two detections of the button status  {    delay(500);    if ( digitalRead(Hall_START) == 0 && is_free == true) //If the device is in idle state, enter working mode    {      is_free = false;      is_working = true;    }  }  START = digitalRead(Hall_START);//Store the status of Hall sensor  END = digitalRead(Hall_END);//Store the status of the second Hall sensor  //Start working  if(is_free == false && is_working == true )  {      SPEED = 100;         //Counter counts, ignore the first detection status      if(count > 500)  { MODEL = OVER; }      count++;  }  //End working  if (MODEL == OVER && END == 0)  {    SPEED = 0;//Reset speed    count = 0;//Reset counter    is_working = false;//Reset working indicator variable    is_free = true;//Reset idle indicator variable    MODEL = 0;//Reset status  }  Serial.println(count);  stepper.setSpeed(SPEED);   stepper.runSpeed();}

Figure 44 Final Product Display

Thus, the flip animation display is fully completed.

In this project, we mastered the working principle of the Hall sensor and learned how to use the 28BYJ-48 stepper motor. With these skills, more interesting animation content can be easily displayed, such as various anime-themed materials. So what are you waiting for? Go try it out!

As the Year of the Tiger Spring Festival is approaching, I wish everyone a happy and healthy new year!