Wiznet makers

How to Build an FPGA Web Counter with WIZnet W5500 Ethernet?

Summary

This project demonstrates a Spartan-6 FPGA evaluation board communicating through the WIZnet W5500 Ethernet controller to implement a real-time web counter system. The FPGA generates counter values internally and transmits them over Ethernet so that the data can be monitored directly from a web browser. By using the W5500 hardwired TCP/IP Ethernet controller, the system achieves stable wired communication without requiring a software TCP/IP stack inside the FPGA.

What the Project Does

The project is an FPGA-based Ethernet communication demonstration developed using a Spartan-6 evaluation board and the W5500 Ethernet controller.

According to the demonstration video, the FPGA continuously generates incrementing counter data and sends the values through Ethernet communication to a web browser interface. The browser displays the counter value in real time, effectively turning the FPGA into a lightweight embedded web server.

The overall system structure is relatively straightforward:

• Spartan-6 FPGA generates counter logic
• W5500 handles Ethernet TCP/IP communication
• Browser receives and displays counter values
• Ethernet provides stable wired transport

This architecture is especially useful for:

• Industrial monitoring systems
• FPGA-based instrumentation
• Ethernet-enabled embedded control
• Educational FPGA networking labs

Unlike UART-based monitoring, the Ethernet interface allows remote access through standard network infrastructure.

Where WIZnet Fits

The W5500 acts as the Ethernet transport engine of the system.

The LK Embedded product page explicitly states that the board includes a W5500 chip for Ethernet connectivity.

Why W5500 Matters in an FPGA System

FPGA designs typically avoid implementing a full software TCP/IP stack because:

• FPGA internal memory is limited
• TCP/IP logic increases HDL complexity
• Software-based networking consumes FPGA fabric resources
• Deterministic logic timing becomes harder to maintain

The W5500 solves this by integrating:

• Hardwired TCP/IP stack
• 10/100 Ethernet MAC and PHY
• Socket engine
• Internal packet buffer memory

As a result, the FPGA only needs to exchange socket data through SPI rather than implement Ethernet protocols directly.

This significantly simplifies FPGA Ethernet development while improving system stability.

Implementation Notes

The official product page confirms that the board integrates the W5500 Ethernet controller.

Verified Hardware Information

From the LK Embedded product description:

“W5500 칩을 내장하여 Ethernet 인터페이스를 제공한다.”

The same description also explains:

• W5500 provides SPI-based Ethernet communication
• MAC and PHY are integrated internally
• Ethernet connectivity can be added without external PHY circuitry 

Conceptual FPGA Integration Flow

Because HDL source code was not publicly available from the provided links, the following is a conceptual integration example based on a typical FPGA + W5500 architecture.

// Conceptual SPI transaction flow for W5500
always @(posedge clk) begin
    if(counter_update) begin
        spi_tx_data <= counter_value;
        spi_start   <= 1'b1;
    end
end

In a typical implementation:

1. FPGA counter logic generates data
2. SPI controller transfers data to W5500
3. W5500 socket engine handles TCP transmission
4. Browser receives Ethernet packets

This approach avoids implementing a software TCP/IP stack directly inside the FPGA fabric.

Practical Tips / Pitfalls

• Verify SPI timing carefully when interfacing FPGA logic with W5500.
• Keep Ethernet PHY traces isolated from noisy switching power circuits.
• Use static IP configuration during FPGA bring-up to simplify debugging.
• Add watchdog recovery for Ethernet link disconnection conditions.
• FPGA clock domain crossing must be handled carefully when transferring SPI data.
• Avoid excessively high SPI clock frequencies during early hardware validation.

FAQ

Q: Why use W5500 with FPGA instead of implementing Ethernet directly?

A: Implementing a TCP/IP stack directly in FPGA logic significantly increases HDL complexity and resource usage. W5500 offloads TCP/IP processing into dedicated hardware, allowing the FPGA to focus on application logic.

Q: How does the FPGA connect to W5500?

A: The connection is typically implemented through SPI. The FPGA controls SPI signals such as SCK, MOSI, MISO, and CS to exchange socket data with the W5500.

Q: What role does W5500 play in this project?

A: W5500 acts as the Ethernet communication engine. It handles TCP/IP packet processing and Ethernet transmission while the FPGA generates the counter data.

Q: Can beginners build this kind of FPGA Ethernet project?

A: Yes, if they already understand basic FPGA HDL development and SPI communication. Using W5500 is much simpler than implementing a complete Ethernet MAC and TCP/IP stack directly in HDL.

Q: How does this compare with a soft-core CPU + LwIP approach?

A: A soft-core CPU with LwIP provides flexibility but consumes more FPGA resources and increases software complexity. W5500 offers a simpler hardware-offload approach with lower development overhead.

Source

• LK Embedded Product Page: LK Embedded Product
• Demonstration Video: FPGA Spartan6 Evaluation Board W5500 Demo

Tags

#W5500 #FPGA #Spartan6 #Ethernet #TCPIP #EmbeddedSystems #SPI #WebServer #IndustrialIoT #WIZnet