Wireless Quiz Buzzer System With ESP Boards

I created this wireless quiz system during my bachelor's year to explore the development of wireless projects. The system consists of four player buttons and one master controller. The master controller identifies which player pressed their button first and can reset the system or remove players from the active list.

Hardware

For the players push button

1. 4 x Enclosure
2. 4 x ESP01s board
3. 4 x Arcade push button
4. 4 x White LED: for each button
5. 4 x Metal switch button: self locking system
6. 8 x 18650 Battery:
7. 4 x Two 18650 in series Battery holder
8. 4 x Step down converter: step down to 3.3V
9. 4 x Charge protector: HX-2X-A10
10. 1 x PCB
11. Wires
12. Header Pins

For the master controller :

1. 1 x Enclosure
2. 1 x ESP32
3. 5 x Colored LED: for each button
4. 5 x Button: Self-resetting pbs-33b
5. 1 x Passive Buzzer
6. 1 x PCB
7. 1 x Female USB C port
8. 5 x 330 Resistors
9. Wires
10. Headers pins

I drilled a hole in the top cover of my enclosure to install the arcade push button. Then, I drilled a smaller hole for the metal on/off switch. Finally, I cut the PCB and soldered everything according to the circuit diagram.

I drilled holes in the enclosure for the LEDs, buttons, and USB-C port, then installed the buttons, LEDs, and USB-C port. After that, I connected them to the ESP32 on the PCB and added the buzzer.

The buttons communicate with the master controller using the ESP-NOW protocol. Each button operates in one of five states, dictating its behavior:

They have 5 state dictating their behaviour:

1. State 0: Waits for the quiz button to be pressed. When pressed, it sends the board number to the master controller.
2. State 1: Blinks 5 times, then changes to State 0.
3. State 2: Blinks once, then changes to State 4.
4. State 3: Turns off the LED.
5. State 4: Turns on the LED.

The master controller can change the state of the buttons.

For example, when the master controller receives data from the Red quiz button, it:

1. Sends State 3 to the other quiz buttons to turn off their LEDs.
2. Activates the onboard LED corresponding to the Red quiz button.
3. Sends State 2 to the Red quiz button, which turns on its onboard LED.

If the button on the master controller corresponding to the Red quiz button is pressed, the system:

1. Turns off the corresponding onboard LED.
2. Sends State 3 to the Red quiz button.
3. Removes the Red quiz button from the player list.
4. Sends State 0 to the other quiz buttons to reset them.

When the reset button (White) on the master controller is pressed, it:

1. Sends State 1 to all quiz buttons.
2. Blinks all its onboard buttons 5 times."

I made this project a while ago when I first began my prototyping journey, so there are plenty of improvements that could be made, including:

1. The power supply is overkill for the task at hand, using a battery with built-in over-discharge protection would eliminate the need for a charge controller.
2. A single 18650 battery or a smaller one would be sufficient to power the system for hours or even days (though this requires testing).
3. If a single battery is used, the DC-to-DC converter could be replaced by a diode to provide the necessary voltage drop.
4. The enclosure could be made of lighter materials or redesigned and 3D-printed for a more efficient build.
5. A charging system could be integrated to allow the batteries to be charged onboard.
6. The communication between the buttons and the master controller could be further optimized to reduce data transfer over Wi-Fi by leveraging the built-in data confirmation feature of the ESP-NOW protocol.