Matrix Display (ESP32 + RS485 + HUB75)

This project reads data from a FATEK PLC over Modbus RTU (RS485) and shows status messages on a HUB75 LED matrix panel.

The firmware runs on ESP32 and uses two FreeRTOS tasks:

• one task for Modbus communication;
• one task for LED matrix rendering.

What This Application Does

• Reads PLC coils and registers (M, D, R) through Modbus RTU.
• Converts selected register ranges into text.
• Chooses a display scenario based on PLC state.
• Shows 3-line messages with centered text and smooth scrolling.
• Detects PLC communication timeout and shows error status.

Scenario Priority and Hierarchy

The firmware always shows only one active scenario, based on this priority order (top = highest priority):

1. Scenario 6 - Communication error
   Condition: Modbus communication timeout.
   Display: Acest post este INDISPONIBIL E0

2. Scenario 7 - Unavailable
   Condition: M120 = 0 (only when communication is OK).
   Display: Acest post este INDISPONIBIL E1

3. Scenario 5 - Pause finished
   Condition: M99 = 1 and D0 > 0.

4. Scenario 4 - Pause
   Condition: M97 = 1 and D0 > 0.

5. Scenario 3 - Function display
   Condition: M94 = 1, exactly one of M71..M79 = 1, and D0 > 0.

6. Scenario 1 / 1.1 / 1.2 - Welcome states (D0 = 0)

   • Scenario 1: M320 = 1
   • Scenario 1.1: M322 = 1
   • Scenario 1.2: M321 = 1
     Internal text selection order in code: 1.2 -> 1.1 -> 1.

7. Scenario 2 - Amount introduced
   Condition: D0 > 0 (used when higher-priority scenarios are not active).

Some lines are static and some lines scroll from right to left, based on scenario and text length.

FATEK Registers Used and Where They Are Used

M Coils (Discrete Relays)

• M71..M79 (0x817..0x81F): select active function group in Scenario 3 (exactly one active).
• M94 (0x82E): enables Scenario 3 logic.
• M97 (0x831): enables Scenario 4 (Pause).
• M99 (0x833): enables Scenario 5 (Pause finished).
• M120 (0x848): availability flag (0 -> Scenario 7 unavailable message).
• M320 (0x910): Scenario 1 (welcome + minimum amount).
• M321 (0x911): Scenario 1.2 (welcome variant with Boxa + ATM message).
• M322 (0x912): Scenario 1.1 (welcome variant with tokens message).

D Registers (Data Registers)

• D0 (0x1770): core amount/status condition (D0 = 0 for welcome states, D0 > 0 for amount-based states).
• D10 (0x177A): used in Scenario 1 to build minim X Lei/Leu.
• D47..D49 (0x179F..0x17A1): time/value formatting for Scenario 3 and Scenario 5.
• D57..D59 (0x17A9..0x17AB): time/value formatting for Scenario 4.

R Registers (Holding Registers)

• Used ranges: R10..R99 (0x0A..0x63) and R110..R199 (0x6E..0xC7).
• These registers hold ASCII text payload for Scenario 3.
• Mapping by active M bit:
  • M71 -> line 1 from R10..R19, line 2 from R110..R119
  • M72 -> line 1 from R20..R29, line 2 from R120..R129
  • M73 -> line 1 from R30..R39, line 2 from R130..R139
  • M74 -> line 1 from R40..R49, line 2 from R140..R149
  • M75 -> line 1 from R50..R59, line 2 from R150..R159
  • M76 -> line 1 from R60..R69, line 2 from R160..R169
  • M77 -> line 1 from R70..R79, line 2 from R170..R179
  • M78 -> line 1 from R80..R89, line 2 from R180..R189
  • M79 -> line 1 from R90..R99, line 2 from R190..R199

Colors Used

The display uses RGB colors from code (via color565 conversion):

• White: (255, 255, 255) for welcome messages (Scenarios 1/1.1/1.2)
• Light green: (128, 255, 128) for Scenario 2
• Red: (255, 0, 0) for Scenarios 6 and 7
• Orange: (255, 128, 0) for Scenario 4 title
• Pink: (255, 128, 128) for Scenario 5 title lines
• Blue accent: (128, 128, 255) for time lines in Scenarios 3/4/5

Scenario 3 line colors by function bit:

• M71: (0, 255, 128)
• M72: (0, 128, 255)
• M73: (255, 0, 255)
• M74: (0, 255, 255)
• M75: (128, 255, 0)
• M76: (255, 0, 128)
• M77: (128, 0, 255)
• M78: (0, 255, 0)
• M79: (255, 255, 0)

Hardware and Communication

• MCU: ESP32
• PLC link: RS485 (Modbus RTU)
• Matrix: HUB75, configured as 64x32, chain 1
• HUB75 to ESP32 pin mapping used in this project:
  • R1 -> GPIO25
  • G1 -> GPIO26
  • B1 -> GPIO27
  • R2 -> GPIO14
  • G2 -> GPIO12
  • B2 -> GPIO13
  • A -> GPIO23
  • B -> GPIO19
  • C -> GPIO18
  • D -> GPIO5
  • E -> -1 (not used for current panel setup)
  • LAT -> GPIO32
  • OE -> GPIO15
  • CLK -> GPIO33
• Modbus serial defaults in code:
  • RX: 16
  • TX: 17
  • RE/DE: 4
  • Baud: 115200
  • Slave ID: 1

For deeper technical details about FATEK register maps, addressing, and protocol behaviour, use the manuals below (local PDFs under Manuale/ when you have them in your copy of the project) and the official references.

Official / general references (web)

• Modbus Organization — specifications — Modbus Application Protocol (function codes, PDU framing).
• Check FATEK official documentation / downloads on fatek.com for the latest PLC manuals for your CPU series (register maps may vary by model).

FATEK PLC communication (local PDFs)

Document	Path (relative to repo root)
PLC binary communication protocol (user manual, EN)	Manuale/08_M_PLC_Binary_Communication_Protocol_User_Manual_en.pdf
FB / FBs reference (B1 / B1z)	Manuale/FATEK_FB_FBs_B1_B1z.pdf
WinProladder manual (EN)	Manuale/Comunicare/FATEK manuals/WinProladder_Manual_en.pdf
Supplement chapters	Manuale/Chapter_12.pdf, Manuale/Appendix1.pdf, Manuale/Apendix 2.pdf

These explain how FATEK exposes coils/registers over communication and how addressing relates to ladder programming tools.

Modbus RTU — messages, functions, RS485 (local PDFs)

Folder: Manuale/Comunicare/Curs ModBus RTU/

Topic	File
Overview / history	Modbus+History+and+Overview.pdf
RTU vs ASCII	Modbus+RTU+vs+ASCII.pdf
Message structure	Modbus+Message+Structure.pdf
Function codes	Modbus+Function+Codes.pdf
Addressing	Modbus+Addressing.pdf
Serial / transmission	Modbus+Serial+Transmission+Modes.pdf
RS485 physical layer intro	RS485+Serial+Communication+Standard.pdf
Troubleshooting	Modbus+RS485+Troubleshooting+Quick+Reference.pdf
Course notes	Modbus_RS485_Course_Notes-Laurens_Vanhoyland.pdf

RS485 hardware & Modbus specification (extra local PDFs)

Folder: Manuale/Comunicare/RS485 proiect/documentatie/

• modbusprotocolspecification.pdf — Modbus protocol specification copy
• MAX485.pdf — RS485 transceiver datasheet notes
• Chapter_13.pdf, Modbus_RS485_Course_Notes-Laurens_Vanhoyland.pdf

Note: If Manuale/ is not in your GitHub clone, copy these folders from your archive or download manuals from FATEK / Modbus.org so links stay meaningful locally.

Project Structure

• main/main.ino - main firmware, display scenarios, task creation.
• main/FATEKModbus.h - Modbus data structures and API.
• main/FATEKModbus.cpp - Modbus polling, parsing, error handling, communication state.

Wiring and Reference Images

HUB75 Connector

ESP32 Pinout (NODE32S)

ESP32 Dev Board 10 Pinout

HUB75 Port Orientation Used

Dependencies

This project uses:

• ESP32-HUB75-MatrixPanel-I2S-DMA (HUB75 library)
• eModbus (Modbus RTU client on ESP32)
• Arduino Core for ESP32 (Arduino core/framework components)

License

This repository is licensed under GNU General Public License v3.0 (GPL-3.0).

See the full license text in the LICENSE file.

Third-Party License Notes and Credits

This project includes or depends on third-party software with permissive/compatible licenses:

• HUB75 library (ESP32-HUB75-MatrixPanel-I2S-DMA) - MIT License - GitHub
• eModbus - MIT License - GitHub
• Arduino core/framework parts - LGPL-compatible usage - GitHub

Compatibility note:

• MIT-licensed code is compatible with GPL-3.0 and can be used in a larger GPL project.
• Arduino LGPL components are also compatible with this use model.

Important obligations kept by this project:

• Original copyright/license notices from MIT dependencies must be preserved.
• Third-party license terms remain valid for their own code parts.
• This project-level license (GPL-3.0) applies to the project as distributed.

If you redistribute this project, keep this README.md, the LICENSE file, and all required third-party attribution/license notices.