Project Details

Basic Setup:

Arduino Mega w ESP 8266 

CNC Shield

Arduino Nano on Print head

4 x LDO6AJSA LED Driver boards link

4 x 3W 380nm UV LED link

1 x Heatsink link

I. System Architecture Diagram

The system operates across three distinct tiers, separating the user interface, the motion control, and the real-time hardware execution.

======================================================================
                  TIER 1: THE NETWORK HUB (ESP32)
======================================================================
  [ Web Browser ]  --> HTTP POST (JSON) -->  [ ESP32 Web Server ]
  - User draws UI                            - Broadcasts standalone AP
  - Sends gridData                           - Hosts index.html & app.js
                                             - Converts JSON to Hex
                                                      |
                                                      | Serial2 (115200 Baud)
                                                      | TX/RX Protocol
                                                      v
======================================================================
               TIER 2: THE MAIN BRAIN (Mega 2560 + CNC Shield)
======================================================================
  [ Arduino Mega 2560 ] <----> [ Hardware Peripherals ]
  - Parses Hex image data      - X, Y, Z Stepper Motors
  - Calculates Mesh Bed        - SSD1306 OLED Screen
    Leveling (MBL)             - SD Card (Config & Mesh Storage)
  - Orchestrates X/Y motion    - User Input Buttons
                                                      |
                                                      | Serial1 (115200 Baud)
                                                      | TX/RX Protocol
                                                      v
======================================================================
               TIER 3: THE PRINTHEAD MCU (Nano Custom PCB)
======================================================================
  [ Arduino Nano ] <---------> [ Printhead Hardware ]
  - Real-time peripheral device - D10, D11, D12, D13: 4x UV LEDs
  - Never blocks UART          - D3, D7: CR Touch (Servo & Signal)
  - Microsecond timers         - A0-A5: TMP36 Temp Sensors
                               - D8: NeoPixel Status Indicator
======================================================================

I. System Architecture

The system operates across three distinct tiers, separating the user interface, the motion control, and the real-time hardware execution.

TIER 1: THE NETWORK HUB (ESP32)

• Input: Receives HTTP POST (JSON) from the User's Web Browser.
• Core Functions: * Broadcasts a standalone Wi-Fi Access Point.
  • Hosts the index.html and app.js frontend files.
  • Converts the JSON pixel arrays into Hexadecimal strings.
• Output: Sends data down to Tier 2 via Hardware Serial2 (115200 Baud).

TIER 2: THE MAIN BRAIN (Arduino Mega 2560)

• Hardware Attached: CNC Shield V3 (X, Y, Z Steppers), SSD1306 OLED Screen, SPI SD Card Module, and physical UI buttons.
• Core Functions: * Parses the Hex image data from the ESP32.
  • Calculates the Mesh Bed Leveling (MBL) interpolation.
  • Orchestrates the X/Y physical motion path.
• Output: Sends real-time hardware triggers down to Tier 3 via Hardware Serial1 (115200 Baud).

TIER 3: THE PRINTHEAD MCU (Arduino Nano Custom PCB)

• Hardware Attached: 4x UV LEDs (D10-D13), CR Touch (D3 Servo, D7 Signal), 6x TMP36 Temp Sensors (A0-A5), and a NeoPixel Status LED (D8).
• Core Functions: * Operates as a real-time peripheral device (never blocks the UART line).
  • Executes microsecond-precise UV exposure timers.
  • Manages the CR Touch deployment and background thermal polling.

II. Protocol: Website to ESP32 (The Payload)

The frontend uses a simple, modern REST approach to send the user's design to the ESP32.

1. The HTTP POST Request When the user clicks "Print," the JavaScript fetch API fires a JSON payload to the "/print" ESP32's endpoint.

• Format: JSON
• Structure:
  • width (int): The width of the image in pixels.
  • height (int): The height of the image in pixels.
  • pixels (array of ints): A flat, 1D array representing the pixel intensities. Each pixel is an integer from 0 (off) to 15 (max intensity).

2. ESP32 to Mega Translation The ESP32 intercepts this JSON, strips out the network overhead, and compresses the pixel array into a single, continuous hexadecimal string to save RAM on the Mega. It sends this over hardware UART.

• Format: P:[width],[height]:[HexData]\n
• Example: P:8,8:000F0000FF00FF00...
• Mechanics: 0 stays 0, 15 becomes F. The Mega reads this string, unpacks the hex characters back into integers, and loads them into its local memory for serpentine printing.

III. Protocol: Mega to Printhead (The Hardware UART Dictionary)

The Arduino Nano operates as a strict, non-blocking peripheral. It sits on Serial1 at 115200 baud, listening for newline-terminated ASCII commands. It immediately executes them and responds with a status string and a NeoPixel color flash.

Command Reference Table