The award-winning Tessera SX40 is Brompton’s flagship 4K LED processor. It combines an industry-leading feature set and easy-to-use software interface with Brompton’s highest-ever capacity processor.
Video input supports full 4K at 60Hz with 12bits per colour via HDMI 2.0 and 12G SDI. All internal video processing takes place within an Intel Arria 10 FPGA with an x86 computer-on-module running software for management and configuration. Output is 10G Ethernet over fibre or copper cables that link to Brompton’s Tessera XD data distribution unit, providing breakout to 1G Ethernet for connection to daisy-chains of LED panels.
The hardware and software, including FPGA configurations, were all developed in-house by Carallon, and we talked to some of the engineers involved:
Philip Smith - Engineering Manager (Electronics) was responsible for the design and testing of the 10G copper and 10G fibre interfaces for the SX40 platform, working with technologies including SFP+, XFI and SFI.
Adrian Jeakins - Engineering Manager (Software) was the software lead, working on the board bring up, porting the common software stack to the new system, and then developing the software needed to connect the UI to the new processing hardware. He also developed the Linux driver stack for the custom 10G Ethernet pipeline and the highly custom packet flows that the system uses both in software and in the hardware in the XD distribution unit.
Philip: From a technical point of view, this was the highest speed circuit we had dealt with, so I anticipated facing some interesting technical challenges through the whole process - from the initial design stages through to manufacture and design validation.
Adrian: Before we started I didn't really anticipate any great specific challenges - possibly an initial lack of experience on my part! I didn't think it was going to be easy but I was confident we'd be able to do it and excited to be making some new and truly cutting edge.
Philip: SFP+, XFI and SFI all involve SERDES links running at approximately 10Gbps. As I'd anticipated, these speeds require careful attention be paid to not only the schematic design but also quite crucially the PCB design and PCB materials used. Test and measurement at these speeds was also particularly challenging, and "10G Ethernet over copper" is very sensitive. It took some healthy trial and error to make sure it was solid and absolutely reliable.
Adrian: The high data rates of 10G Ethernet management proved a major challenge. It was very tricky to investigate and debug both because the signals are so fast and since the system was generating data at such a high volume. The thermals of the system were also more of a challenge than I expected, so it was rewarding when we got it right.
Philip: From a technical view – a large amount of experience and knowledge was gained working with the high speed signals which can be applied to future projects to their hopeful success. Stepping back, one key thing is not to underestimate just how long these large projects take. Getting the board design done and prototypes is often only a very small part of the picture - perfecting the software, testing and moving to production takes a huge amount of time.
Adrian: I learned an enormous amount; both technical and about how to plan and running a project of this scale and duration. It was my first time leading a hardware project and mentoring junior embedded devs taught me a lot about how to introduce concepts and work as a team. I also learned a lot more about advanced switching (use of extensive VLANs, TCAM for dynamic switch routing and DSA).
Overall, while the project was undeniably hard, it was also extremely rewarding, and it is fantastic to have built something like this from scratch, nursed the first units into life and then to see it being produced in volume and being used on so many amazing projects with consistently great feedback from our users.
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