Product request: Stackable 2x/4x M.2 E key extension board for Rock5B SBC

ROCK 5 Series
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Hi Radxa / @jack,

For previous Rock SBC:s you made a stackable board for attaching one M.2 22x80mm: https://wiki.radxa.com/Rockpi4/hardware/M2_extend

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Your new Rock5B is a quite powerful computer and it can be relevant to add more high speed peripherals to it.

A stacked board would have the PicoITX form factor of 100 x 72mm. This is space for total FOUR M.2 22x80mm slots if you make it two on each side. (Three M.2 22x80mm slots could be fit on one side too..)

The kind of hardware I want to put in the M.2 slot is SSD:s. Also 10gbe ethernet: EGPL-T101 This Tiny 10GbE NIC Slots Into an M.2 Port | Tom's Hardware Innodisk Releases the World’s First 10GbE LAN Module in M.2 Form Factor - Innodisk Corporation .

The stacking could be done both down or up from the SBC. If up, there needs to be space for the Rock5B’s fan - if below the space could be allowed to be very tight.

Here I have two requests for you, one simpler and one more advanced:

  • Firstly, can you make a stackable extension board with 2x M.2 22x80MM total on it, that is based on bifurcation: each M.2 slot gets two PCIe v3 lanes.

The total dedicated bandwidth for each of the two M.2’s will be 16gbit = 2GB/second which is plenty. This way one Rock5B can have 10gb ethernet and one M.2.

Please let me know if you plan to make this board this year, I would like to buy it.

Here all the four M.2:s share 32gbps = 4GB/sec bandwidth. Supposedly the bandwidth sharing will work out smoothly.

In the PicoITX form factor this will be the most powerful computer on the market.

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@rock you wrote E-key in the title, yet the devices you want to use are m.2 B+M. M key slots make sense, E key do not.

I personally would love to see a board with either 4x amply spaced m.2 m key, or 4x full-size pcie, and appropriate power input.

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The second idea with a PCI switch and 4x M.2 80 slots would be great for a silent RAID array. Now, if there were a handy way to handle hardware redundancy of the CPU module (other than a complete clone of the setup) that would be fancy!

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Main problem. Are you sure that this module works under ARM?

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@Dante4 Sorry but what do you mean. NVMe SSD:s work with ARM. I believe you were not well informed, writing that.

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@rock there were nothing about NVMe SSD. I was talking about EGPL-T101, since not all 5\10\25\40\100G NICs are working as intended with ARM. For example ConnectX-3 doesn’t work at all with ARM.

Also at the moment of may 2021 it was unknown will Rock5 work with PCIe switch, since RockPi4 did not worked with them.

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@Dante4 ah I see that some rare PCIe cards will not work with ARM. Is that because they have proprietary drivers? Or badly written firmware?

It would be interesting with a PCIe switch based extension board for the Rock5B e.g. using ASM2824 (https://www.anandtech.com/show/13022/asmedia-preps-asm2824-pcie-30-switch).

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I never liked all those m.2 extension boards based on ribbon cables. I think that guys from khadas had much better approach to divide signals from m.2 to two m.2 (B+M and E):

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Of course here we should talk abou 1x m.2 B+M to 2x or 4x B+M,
I think it should have size of rock5 and look like the one from khadas

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Usage is simple - You should be able to connect 2x nvmes or nvme + sata - both utulizing 2x pcie 3.0 lanes.
Of course 4x m.2 - each with 1x pcie 3.0 is also some option but not that sweet :wink:

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I just checked sizes, using this design (thin pcb that inserts right into m.2) only two non extending m.2 can be fitted on bottom. Three are possible, four if card will extend under ports (2280).
I’m not sure what is included in rock5 m.2, but maybe there is something more than just 4x pcie 3.0. Then maybe 3x m.2 is possible.
As bonus such board could have more than 2280 mounting holes to use with small 2230-2280 modules. Also such board is cheaper than any other with cables and connectors.

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Good question. I wouldn’t say “badly written firmware” more like “compatible only with x86”. For example NC552SFP works with RockPi4 and Rock5, but NC550SFP just simply refused to show in lspci on RockPi4