Mug Heater Project

This project uses the Nucleo STM32-F303K8 microcontroller to create a mug heater device that keeps your drink warm. The device is powered by USB-A.

Contents Overview

1. Project Overview
2. Device Images
3. Circuit Diagram
4. Connected Components
5. System Features
6. Assembly and Setup
7. 3D Printing Files
8. Future Improvements
9. Important Considerations
10. License

Project Overview

The mug heater is designed to:

• Maintain your drink at a desired temperature (default: 60°C).
• Be simple and portable with USB power.
• Use a combination of an NTC thermistor, a MOSFET, and a buzzer for temperature control and alerts.

Device Images

Circuit Diagram

Connected Components

• Load switching MOSFET gate on PA11
• NTC Thermistor on PA3
• Buzzer on PA5 which indicates a reached temperature
• Button on PA7 which turns off and on the heating
• LED on PA4 which indicates the mode of heating:
  • Flashes and then on: Starting heating
  • Flashes and then off: Stopping heating

System Features

• Temperature Control: Reads ADC every 10 seconds and adjusts the load based on a specified temperature (default: 60°C).
• On/Off Button: Turns heating on or off and toggles an indicator LED.
• Buzzer Alert: Plays a sound when the specified temperature is reached.
• LED Feedback: Temperature is displayed as blinks (1 blink per 10°C).
• Debounced Button: Ensures stable toggling with a 50ms debounce threshold.
• Failsafe Temperature: System ignores invalid temperature readings and keeps the load off.

Assembly and Setup

1. Required Components:

   • Nucleo STM32-F303K8 board
   • MOSFET: BUK542-100A (for load switching)
   • 10k NTC Thermistor: R3
   • Buzzer: 2400Hz
   • Button: HX TS-1101-C-W
   • LED: LED-0603_R
   • Resistors:
     • R1: 10kΩ (pull-down for NTC thermistor)
     • R2: 510Ω (series resistor for button)
     • R4: 300Ω (current limiting for LED)
     • R5: 510Ω (NRST Short See Notes)
   • USB-A power source
   • Load: 3.4Ω heating element

2. Setup Instructions:

   • Connect the peripherals as shown in the Circuit Diagram.
   • Flash the microcontroller with the provided firmware.
   • Assemble the device with proper insulation for the heater.

3. Programming:

   • Use PlatformIO with VS Code for flashing the microcontroller.

4. Testing:

   • Verify temperature control functionality.
   • Test the buzzer, button, and LED indicators.

3D Printing Files

The following files are included for 3D printing the device components:

• 3d_print/02_Wire_Plate.SLDPRT
• 3d_print/03_Base.SLDPRT
• 3d_print/04_Top_Base.SLDPRT
• 3d_print/05_Aluminum_Plate.SLDPRT

These files can be used to fabricate the structural parts of the mug heater.

Future Improvements

1. Plastic casing does not lock in place. It needs larger gap around locking mechanism.
2. Custom PCB
3. PID heating control
4. Custom buzzer sounds - like Star Wars Imperial March etc.
5. Automatic shutdown

Important Considerations

• A 510-ohm short from NRST to 3.3V is required to power the device with a single cable. This bypasses the issue where the ST-LINK pulls down the NRST pin, causing the microcontroller to remain in reset when ST-LINK is disconnected.
• Ensure proper insulation for the heating element to prevent accidental burns or short circuits.

License

This project is open-source under the Apache License. Feel free to use and modify it!