Mesa Clone FPGA + Ethernet Interface Project

Overview

This project aims to replicate the functionality of Mesa FPGA boards (like 7i76 + 7i92) using custom hardware:

• Cinterion EHS6T LAN Module (Ethernet-to-RS232 modem)
• Googoltech GTS800 board (FPGA: Lattice MachXO2)
• LinuxCNC running on Debian 12

The core idea is to bridge Ethernet TCP over a specific port (1716) to RS232 UART, enabling real-time control via a custom LinuxCNC HAL (Hardware Abstraction Layer) module. This setup allows for a flexible and customizable CNC control solution without relying on proprietary Mesa hardware.

Project Goals

• Mesa-like Functionality: Emulate critical features such as Step/Direction generation, encoder feedback, and general-purpose I/O.
• Real-time Communication: Achieve near-real-time data exchange between the FPGA and LinuxCNC for precise machine control.
• Customizable Hardware: Utilize the GTS800 FPGA for fully customizable logic tailored to specific CNC needs.
• Robust & Stable System: Develop a reliable communication and control infrastructure on Debian 12.
• Open-Source Focused: Provide a framework that can be further developed and extended by the community.

Directory Structure

.
├── docs/                # Comprehensive project documentation, setup guides, protocol specs
├── fpga_design/         # VHDL/Verilog source code for the GTS800 FPGA
│   ├── src/             # Core FPGA design files (.vhd, .v)
│   └── bitstreams/      # Compiled FPGA bitstream files (.bin, .sof, .bit)
├── hal_module/          # LinuxCNC HAL custom module source code
│   ├── src/             # C/C++ source for the HAL component (.c, .comp)
│   └── build/           # Build artifacts (e.g., compiled .so files)
├── scripts/             # Python, Bash, or other utility scripts for testing, setup, or automation
├── tools/               # Any specific tools or utilities (e.g., FT_PROG equivalents, custom flashers)
├── .gitignore           # Specifies intentionally untracked files to ignore
└── README.md            # Project overview and main documentation entry point

Initial Setup & Configuration

Hardware Connections

1. GTS800 FPGA to EHS6T LAN Module (UART):

   • Connect GTS800 UART TX to EHS6T UART RX.
   • Connect GTS800 UART RX to EHS6T UART TX.
   • Ensure common ground (GND) is connected.
   • Baud Rate: To be configured identically on both devices (e.g., 115200, 230400, 460800 Baud).
   • Data Format: Typically 8N1 (8 data bits, no parity, 1 stop bit).

2. EHS6T LAN Module to LinuxCNC Host (Ethernet):

   • Connect an Ethernet cable from the EHS6T LAN port to your LinuxCNC host PC's Ethernet port.
   • Ensure the EHS6T module is powered on and its network interface is active. It is expected to be accessible at on TCP port .

LinuxCNC Host Network Configuration (Debian 12)

1. Verify Network Interface: Ensure your LinuxCNC host's Ethernet interface is properly configured and within the same subnet as the EHS6T (). Static IP configuration is recommended for stability.
   • Example for (replace with your actual interface name):

     auto eth0
     iface eth0 inet static
         address 192.168.1.100
         netmask 255.255.255.0
         gateway 192.168.1.1 # Optional: if internet access is needed
     

   • After modifying, restart network service:
2. Test Connectivity:

   ping 192.168.1.140

   You should receive replies.

Next Steps in Development

• FPGA Protocol Design: Define the UART communication protocol between FPGA and EHS6T, including commands for reading/writing registers, error handling, and checksums.
• FPGA Logic Implementation: Develop VHDL/Verilog code for the GTS800 to emulate Mesa registers and implement I/O logic.
• HAL Module Development: Create the custom LinuxCNC HAL module in C/C++ to handle TCP socket communication with EHS6T and protocol translation for the FPGA.
• Testing & Debugging: Develop Python scripts for initial testing of TCP/UART communication and use LinuxCNC's HAL tools for debugging.

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