How to Build a CLHS 25 Gbps Solution in an FGPA

Keeping pace with machine vision standards updates can be difficult. Camera Link HS (CLHS), for example, released some significant updates in version 1.2 in late 2022 at The Vision Show in Boston. The updates included a major speed upgrade that allows the machine vision standard to reach speeds of 25 Gbps on an FPGA using 25 Gbps transceivers over fiber with SFP28, QSFP28, or MPO connectors. 

This and several other relevant updates were covered in a previous blog on CLHS v1.2 updates written by Mike Miethig, R&D Camera Development Manager at Teledyne DALSA and Chair of the Camera Link HS committee for Vision Systems Design. These updates include CLHS 25 Gbps’ backward compatibility to 10 Gbps, the features of the IP core, FPGA implementation, and future CLHS plans. 

>>>Related: View more information on CLHS here. 

In another article written by Miethig for Quality Magazine, “CLHS IP Core Enables 25 Gbps Products To Quickly Reach The Market,” takes a deeper look at the standards IP core and how it can operate at 10G, 25G, and—in the future—50G. Miethig writes that the IP core used to achieve 25 Gbps in the X Protocol—one of the two physical layer encodings, with M protocol being the other—is the same IP core found in all 10 Gbps CLHS products on the market today. In other words, achieving 25 Gbps does not require a new IP core or purchase. He then goes on to describe the steps required to create a CLHS 25 Gbps solution in an FPGA for a camera with a 2048 x 1024 monochrome sensor with 12-bit output running at 950 fps. 

In this setup, an SFP28 connector is chosen. The VHDL core purchased from A3 for $1,000 includes the CLHS camera and frame grabber modules and the CLHS physical coding sublayer (PCS), and has been implemented on AMD (Xilinx), Intel (Altera), and MicroChip (PolarFire) FPGAs. While the developer must configure the transceiver function, clock distribution, and the logic that passes messages to and from the core, the CLHS core handles packet building, encoding, and priority rules. 

Read the rest of Miethig’s description on creating a CLHS 25 Gbps solution.