FPGA + USB 3.0: Cypress EZ-USB FX3 or XillyUSB?

Introduction As the title implies, this post compares two solutions for connecting an FPGA to a host via USB 3.0: Cypress’ FX3 chipset, which has been around since around 2010, and the XillyUSB IP core, which was released in November 2020. Cypress has been acquired by Infineon, but I’ll stick with Cypress. It’s not clear [...]

Ultrascale GTH transceivers: Advanced doesn’t necessarily mean better

Introduction I tend to naturally assume that newer FPGAs will perform better in basically everything, and that the heavier hammers are always better. Specifically, I expect the GTX / GTH / GT-whatever to perform better with the newer FPGAs (not just higher rates, but simply work better) and that their equalizers will be able to [...]

Setting up Si5324/Si5328 on Xilinx development boards

General These are my notes as I set up the jitter attenuator devices (Silicon Labs’ Si5324 and Si5328) on Xilinx development boards as clean clock sources for use with MGTs. As such, this post isn’t all that organized. I suppose that the reason Xilinx put a jitter attenuator to drive the SFP+ related reference clock, [...]

Xilinx Ultrascale / Ultrascale+ GTH/GTY CPLL calibration

… or why does my GTH/GTY not come out of reset? Why are those reset_rx_done / reset_tx_done never asserted after a reset_all or a reset involving the CPLLs? What’s this CPLL calibration thing about? It turns out that some GTH/GTY’s on Ultrascale and Ultrascale+ FPGAs have problems with getting the CPLL to work reliably. I’ll [...]

Cyclone V and some transceiver CDR/PLL parameters

Introduction Connecting an Intel FPGA (Altera) Cyclone V’s Native Transceiver IP to a USB 3.0 channel (which involves a -5000 ppm Spread Spectrum modulation), I got a significant bit error rate and what appeared to be occasional losses of lock. Suspecting that the CDR didn’t catch up with the frequency modulation, I wanted to try [...]

HTG’s USB 3.0 FMC module: Things you surely want to know

Introduction I purchased a HiTech Global 3-Port USB 3.0 SuperSpeed FMC Module (also known as USB3 FMC), which is an FPGA Mezzanine Card, primarily based upon TI’s SuperSpeed USB 3.0 Transceiver, TUSB1310A. Even though this board works fine at the end of the day, my experience with it was full with surprises, not all of [...]

Gigabit tranceivers on FPGA: Selected topics

Introduction This is a summary of a few topics that should to be kept in mind when a Multi-Gigabit Tranceiver (MGT) is employed in an FPGA design. It’s not a substitute for reading the relevant user guide, nor a tutorial. Rather, it’s here to point at issues that may not be obvious at first glance. [...]