UV Curing Box

UV PCB Curing Box

A dedicated, safety-interlocked UV exposure and resin curing chamber controller powered by the ultra-low-cost WCH CH32V003 RISC-V microcontroller, featuring a 4x4 matrix keypad, a 4-digit TM1637 7-segment display, software PWM brightness control, and custom KiCad hardware.

Features

• RISC-V Microcontroller Core:
  • Implemented on the WCH CH32V003A4M6 (QingKe 32-bit RISC-V2A core @ 48 MHz, 16 KB Flash, 2 KB SRAM).
  • Built with the PlatformIO Community CH32V Arduino core (ch32v003fun HAL).
• Fail-Safe UV Safety Interlocking:
  • The high-power UV LED MOSFET (pin A2) is strictly energized ONLY during the active RUNNING state.
  • Transitions to BOOT, IDLE, READY, PAUSED, or FINISHED instantly and continuously force the gate LOW.
• Dual Timing Modes:
  • Timer Mode: Countdown timer with customizable duration (capped at 8:00 minutes) and automated shutoff.
  • Stopwatch Mode: Elapsed time counter with live LED toggling.
• Fast Presets & Matrix Keypad Input:
  • 4x4 matrix keypad interface for direct numeric entry, pause/resume, and reset.
  • One-touch curing duration presets:
    • A: 1:00 min
    • B: 1:30 min
    • C: 2:00 min
    • D: 3:00 min
  • On-the-fly cycle extension (# button adds +5 seconds, clamped to 8:00).
• PWM Exposure Brightness Regulation:
  • 50 Hz sampled software PWM (0–100%) designed to eliminate flicker and ensure accurate optical dose delivery.
  • Dedicated on-screen brightness tuning menu (b 0 to b100).
• Telemetry & Status Display:
  • TM1637 4-digit 7-segment display showing MM:SS with blinking colon indicators during exposure.
• Custom Hardware & PCB:
  • Designed in KiCad with full schematics, PCB routing, 3D step models, and vector silkscreens.

Hardware Specification

Components & Microcontroller

• MCU: WCH CH32V003A4M6 (TSSOP-20).
• Display: TM1637 4-digit 0.36" / 0.56" 7-segment clock display module.
• Keypad: 4x4 tactile matrix keypad.
• Switching MOSFET: N-Channel Power MOSFET (low-side switch on A2 driving 395nm/405nm UV LED arrays).
• Power Input: 12V DC input for LED strings with onboard 5V / 3.3V LDO regulation for logic.

Hardware Prototype & Visual Design

Live Hardware Prototype

Below is the operational controller prototype executing a countdown exposure on the TM1637 4-digit display:

Electrical Schematic

PCB Board Layout & Copper Routing

Complete Board Layout	Top Copper Layer (F_Cu)	Bottom Copper Layer (B_Cu)

Pinout Mapping

State Machine

stateDiagram-v2
    [*] --> BOOT
    BOOT --> IDLE: Initialization Complete
    IDLE --> READY: Digit Entry or Preset (A-D)
    READY --> RUNNING: Press '#' (Start)
    RUNNING --> PAUSED: Press '*' (Pause)
    PAUSED --> RUNNING: Press '#' (Resume)
    PAUSED --> IDLE: Press '*' (Reset to Zero)
    RUNNING --> FINISHED: Time Reaches 0:00 (Timer) or 8:00 (Stopwatch)
    FINISHED --> IDLE: 5s Auto-timeout or Any Key

Project Structure

UV-Curing-Box/
├── Programs/                         # PlatformIO firmware project
│   ├── platformio.ini                # CH32V003 target configuration
│   └── src/
│       └── main.cpp                  # Complete non-blocking state machine & firmware
├── Schematic.pdf                     # Schematic diagram export
├── UV_curing_box.kicad_sch           # KiCad schematic
├── UV_curing_box.kicad_pcb           # KiCad PCB board layout
├── MCU_WCH_CH32V003xxx6.kicad_sym   # Custom CH32V003 symbol library
├── led_string.kicad_sch              # UV LED array layout
├── UV_curing_box.svg                 # Scalable vector graphics board plot
├── .gitignore                        # Git ignore rules
└── README.md                         # Project documentation

Firmware Compilation & Flashing

Using PlatformIO (VS Code / CLI)

1. Install PlatformIO Core and the Community CH32V platform:

   cd Programs
   pio run

2. Connect a WCH-LinkE programmer to the single-wire debug interface (SWDIO on pin D1, GND, 3V3).
3. Upload firmware:

   pio run --target upload

License

Open hardware and embedded firmware. All rights reserved by the author.