Interactive STM32 Quiz with LED & Audio Feedback

Interactive STM32 Quiz with Red/Green LED Feedback & Buzzer

WHAT WE BUILT

We built NeoQuiz as a small, tactile way to turn a serial terminal into a hardware quiz buzzer. I wanted something simple that could run on an STM32 board, show questions on a 16x2 I2C LCD, accept answers over UART, and immediately tell the user whether they were right or wrong using only a buzzer and two LEDs. The result is a compact, reliable demo that’s great for classroom demos, maker nights, or just practicing embedded development with HAL/CubeMX.

Quick Summary

• An STM32-based quiz device that:
• Displays a question on an I2C LCD
• Accepts typed answers over UART (serial terminal)
• Lights a green LED and plays a positive tone for correct answers
• Lights a red LED and plays a negative tone for wrong answers

Components Used

• STM32 development board (STM32F407)
• 16x2 I2C character LCD (with PCF8574 I2C backpack)
• Wires, USB cable

Key features

• UART text input for user answers (serial console)
• I2C LCD display for questions and feedback
• Red and green LEDs for visual feedback (green = correct, red = wrong)
• Passive buzzer (PB0) for audible correct/wrong tones
• Simple STM32 HAL/CubeMX code and a small ws2812b-free driver
• Easy to expand: add more questions, non-blocking sounds, or additional indicators

Wiring

I2C -> STM32

• LCD I2C SDA -> PB7 (I2C1 SDA)
• LCD I2C SCL -> PB6 (I2C1 SCL)
• GND -> GND
• VCC -> 5V

CubeMX (.ioc) settings (how I set it up)

1. MCU: choose your STM32 part (STM32F407)

2. Clock: set system clock to appropriate frequency for your board (default HSI works for this demo).

3. Peripherals:

• I2C1: Enabled, pins PB6 (SCL) / PB7 (SDA) — leave default Timing for 100 kHz or set as required.
• USART1: Enabled, Asynchronous, 9600 baud, pins PA9 (TX) / PA10 (RX).
• GPIO: Configure three pins as GPIO_Output:
• PB0 — Buzzer
• PB10 — Green LED
• PB2 — Red LED
• Set GPIO Pull = NoPull, Speed = VeryHigh (optional).

4. Generate code and open the project in STM32CubeIDE.

How it works

• The MCU displays a question string on the I2C LCD.
• The user types the answer on a serial terminal (9600 baud) and presses Enter.
• The MCU reads the input (blocking read for simplicity), compares it case-insensitively to the stored correct answer, and:
• If correct: lights the green LED and plays a positive buzzer pattern.
• If wrong: lights the red LED and plays a negative buzzer pattern.
• After a short delay the LEDs turn off and the loop repeats.

Source Codes ( Insert all the source code into your src or inc file)

https://github.com/MichelleannArtiaga/-Interactive-STM32-Quiz-with-LED-Audio-Feed/tree/main

Build & flash

1. After adding the code and configuring pins in CubeMX, generate the project and open it in STM32CubeIDE.

2. Build the project (Project → Build).

3. Connect your board to your PC and flash (Run → Debug or use ST-Link utility).

4. Open a serial terminal at 9600 baud, type an answer, and press Enter.

Usage demo

- Power the board and open serial terminal. The LCD will show a question.

- Type "206" and press Enter. If correct, the green LED lights and a pleasant ding sequence plays. If wrong, the red LED lights and a low beep plays.

Video Demo

https://drive.google.com/file/d/1J-3u2UFI7LImi6mL_zV2R8tJtIgQzqxq/view