> Unfortunately, having all of the transceivers in a single quad was a bit limiting due to the 7 series clocking architecture: they share the same QPLL, which has to be at 10.3125 Gbps for 10Gbase-R operation. While the CPLLs can be configured freely, they have a lower Fmax which meant that the BERT / CDR trigger channels cannot operate at arbitrary frequencies above 6 Gbps (most notably, 8 Gbps operation for PCIe gen3 mode is not available).
This one is especially tricky since even if you know what a phased lock loop (PLL) is, the terms CPLL and QPLL are specific to the arrangement of transceivers in these specific Xilinx FPGAs (7 series being one family of FPGAs which came before the UltraScale and then UltraScale+ series). There are four transceivers in a ‘quad’ which can either run from their ‘Channel PLL’ (CPLL) or the shared ‘Quad PLL’ that can run much faster to do basically double the line rate.
Pretty epic. A very impressive case of building one's own tools, or, rather, a one-off tool that seems to do a simple thing. The most impressive aspect is, of course, handling various issues that normally would require making a new PCB, but the author never retreated.
> My original plan had been to use their standard 1U folded sheet metal design, but I discovered too late, after boards were ordered, that it wasn’t going to work due to the 5mm corner mounting holes being inside the keepout area for the rear bend.
I wonder if a less annoying solution would have been to omit the mounting holes and then drill and tap them after the fact, possibly at a slight angle if the metal is out of plane there.
Soldered an ESP32 together with a couple I2C sensors the other week. Didn’t work. Read post, jaw hit floor, maybe I’ll revisit the project soon. Amazing.
This is a really beautiful bit of kit, really like the case and the thought given to signing, but the analog side is really impressive too. Would it be viable to use the same hardware as a base for an NTP server?
I'm glad someone understands this.
I wonder if a less annoying solution would have been to omit the mounting holes and then drill and tap them after the fact, possibly at a slight angle if the metal is out of plane there.