This project recreates the bus stop request bell commonly found on public buses in Singapore. When passengers press the stop button, a bell sound alerts the driver that someone wants to alight at the next bus stop.
The system is built using an ESP32-C3 Super Mini microcontroller, connected to a MAX98357 I2S audio amplifier and a 3W 8Ω speaker. A 3D-printed stop button serves as the user input. When the button is pressed, the ESP32 triggers a bell sound through the speaker.
To keep the device compact and portable, the electronics are powered by a 3.7V 2000mAh rechargeable battery and assembled on a perfboard after prototyping on a breadboard. This project combines embedded electronics, audio playback, and 3D printing to recreate a familiar real-world transport system.
Tested the ESP32 with a 3W 8Ω speaker and MAX98357 I2S amplifier.
I used example code to turn the ESP32 into a Bluetooth speaker to verify that the amplifier and speaker were working correctly.
Result
- Successfully played audio through the speaker.
Connected the button, MAX98357 amplifier, and ESP32 together on a breadboard to begin prototyping the bus stop bell system.
Goal
- Test if pressing the button can trigger the bell sound.
Added a 3.7V 2000mAh rechargeable battery so the device can operate without USB power.
Replaced the standard ESP32 with an ESP32-C3 Super Mini to make the circuit more compact.
Started soldering all components onto a perfboard to make the circuit permanent.
Steps
- Soldered power wires first
- Connected ESP32, amplifier, and battery
Media
