Interactive OUIJA Board

The concept of our Halloween themed project is an Interactive OUIJA board that when it perceives someone's presence through the distance sensor, sends a greeting message saying "hello" via LEDs, moves the planchette to scare them and say goodbye with a "bye" via LEDs.

The following lists include both electronic elements and tools used to assemble a Halloween themed interactive OUIJA board.

ELEGOO UNO R3 Basic Starter Kit

• UNO R3
• Breadboard 1PC
• USB Cable 1PC
• Breadboard Jumper Wire 27PCS
• F-MDupont Wire 4PCS
• Resistor 1 kΩ 6PCS
• Red LED 6PCS
• SG90 Micro Servo Motor 9G 1PC
• Ultrasonic Sensor distance sensors HC-SR04 1PC

OUIJA Board

• Cardboard box
• Black Felt tip pen
• Cutter
• Black Plastic folder
• Glue gun
• Tape

Using the materials listed before, we have created an electrical circuit shown in the electrical connection scheme.

Each LED is connected to a resistance of 1kΩ through the positive cable which are the connected to a pin (13, 12, 11, 8, 7, 6) in the Arduino. The negative wires of the LEDs are linked together to be sent to the ground of the Arduino as a power supply for the circuit. To this ground we have also attached the ground of the ultrasonic sensor and the micro servo motor, shown with black cables.

Regarding the voltage of the circuit, the pin Vcc of the sensor and the red cable of the motor connected to the 5V of the Arduino represented with red wires.

The Trig and Echo pins of the ultrasonic distance sensor are connected to the pins 2 and 3 respectively to the Arduino.

Finally, the yellow cable of the micro servo motor is linked to the pin 9. All of the circuit is supplied by a 9V battery.

This flow diagram shows the steps the circuit follows during the setup and the loop phases.

The planchette is controlled by the servomotor, and the sequence fo messages are created by a series of LEDs.

The servomotor and the LEDs only function when the sensor detects movement up to 25 cm of the board. It sends a signal to the Arduino and the first message appears, then the planchette rotates 4 times, followed by the second message, and finally the LEDs turn off and the servomotor moves to its initial position.

The following instructions clarify each step to assemble the project once the entire circuit is done.

1. Choose a box the size of a ouija board. We have taken out the lid and will work on the bottom face of the box (27cmx34cm for example).
2. Arrange a design, draw it with a marker and cut the letters of the alphabet off with a cutter.
3. Also, make sure to cut out the corresponding holes for the electrical circuit elements.
4. Add some plastic black transparent sheets in order to cover up the holes so that you are not able to see all de cables through them when the LEDs light up and turn off.
5. Finally, place the circuit inside the box, stuck on the back of the bottom face with everything on its reciprocal gap.

To sum up, the following conclusion is where we'll mention all the problems and different decisions we had do make during the making and programming of this whole project. From the planning of our project to the development of bringing it to life.

As the planchette had to be fix we wanted to represent its real movement into an action our Arduino could perform through one of the electrical elements we has learnt on this first half of the course. That is why we decided working with the Servos and ultrasonic distance sensors.

The main problem presented during the making of the circuit and programming it correctly was how to create the sequence between the messages shown with the LEDs and the movement of the servo motor. The two main options were to use a delay() or the millis() functions. Both of them worked correctly but the difference was that, while using the delay() function the three functions were shown one after the other, meanwhile with the millis() function we were able to choose at what point of the circuit each item was going to be functioning with the opportunity of having the message shown and the servo moving at the same time. Finally we resorted to use the delay() function, as we thought it suited more our project to have the first message shown, then the movement of the planchette and to finish off the last message.

Every component mentioned before was going to be managed by an Ultrasonic Sensor distance sensor so that the user can directly interact and be the principal commander of the game.