Modular successor of the famed ULX3S, looking to expand emerging ULX “M” family, ULX5M follows in the footsteps of the ground-breaking ULX4M. But, this one wants to draw its compute power from THE ONLY EUROPEAN FPGA:
CologneChip GateMate
The ULX5M would be the second open-source FPGA On Module (FOM) for the CM4 Raspberry Pi motherboards. Exactly like any other CM4, it is designed to be compatible with BB3-CM4, which is a new, 100% open-source Base Board, currently in the making by Intergalaktik.
Thanks to GateMate’s own modularity /* 1, 2, or 4 FPGA chiplets on a shared interposer */, the compute potential of our openFOM would scale from 20K, 40K to 80K 8-input MUX trees. Double these numbers for the 4-input baseline combos: 40K, 80K, 160K are also the flop counts!
Even higher densities are on the roadmap. 
Note the diversity that this proposal would bring to the current FPGA landscape, saturated with LUT-based devices.
GateMate is one of the rare families designed around MUX combo trees, and not the ubiquitous, mainstream LUTs!
To be fully fair, this combo gain is offset by the loss of Distributed RAM resources, the alter ego of LUT micro memory elements.
Until we create all relevant drawings and pictures, you can get a feel for the concept by looking at the rendition of ULX4M, showing this openFOM as a daughter card for a commercial CM4 RPi baseboard.
Then imagine the ULX5M in its place, with Cologne cathedral instead of Lattice logo on our FPGA, and one important change in the storage department — To counter lower GateMate pin count, we must replace ULX4M:
- Lattice + SDRAM (-LS)
- Lattice + DDR3 (-LD)
options with one-and-only-one type of external memory: HyperRAM.
Hence the ULX5M-CH designation, conveying that this 5th baby in the ULX family feeds on Cologne logic and Hyper memory.
It goes without saying that the ULX5M-CH is intended to be more affordable and more accessible than its older sibling.
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This ULX4M <-> ULX5M swapability objective would be transparent to base board, even for SerDes /*yes, GateMate can do multi-gigabit serial!*/
Yet, it will take some hard work to accomplish our plug-and-play goal, which we plan to reach step-by-step, by porting the peripherals one at a time, aided by an assortment of PMODs, some even made from the scratch.
In the end, as the proverbial cherry on top of the cake goes, we are imagining either ULX4M or ULX5M on top of the BB3-CM4 :> Pick your favorite open-source FPGA to embark on your secure computing project 🙂
This makes for a fully open, vendor-agnostic compute machine, where all hardware is free from backdoor spying, and all needed tools and app sources have nothing to hide.
Can it be more open and, by extension, more secure than this?! If you can think of a security gap, hole, or an improvement, we are open to listen.
With both ULX4M and BB3-CM4 already under NLnet sponsorship, we look at NLnet to help us transform this ULX5M idea to reality. That would entail schematic and PCB design, manufacturing, testing, promotion, support and similar activities, all aiming to facilitate plugging our new ULX openFOM family member into open community ecosystem, sparking interest, and complementing it by a suite of solid and secure examples.
This project is currently in the planning phase.
Stay tuned for updates…
