Rock 5B accessory

ROCK 5 Series
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  • the SoC on the PCB dictates the options.
  • those Khadas accessories do not support bifurcation. Khadas SBCs usually lack any decent I/O since Amlogic based and those SoCs feature 1 PCIe Gen2 lane maximum and this multiplexed with USB3. You get either PCIe or USB3 there (only exception are Khadas Edge thingies since based on Rockchip).
  • you won’t get SATA in the M.2 key M slot on Rock 5B since the 4 lanes routed here are PCIe Gen3 only (provided by a dedicated PCIe 3.0 controller in RK3588).
  • you have SATA already in the M.2 key E slot since this slot can be turned from PCIe Gen2 to SATA with a simple device-tree overlay and a mechanical adapter Radxa is going to sell for a few bucks.
  • all most of those WWAN modems are USB based anyway even if they come in mPCIe or M.2 format (as such you can attach these cards with a simple adapter board to an USB2 port if really needed).
  • just checked it on my dev sample: the 4 pin PoE header is there next to the GPIO header. So I guess Radxa’s PoE+ HAT will fit (though with the SoC on the upper PCB side thermally challenging).

A mechanical adapter for the M.2 key M slot with bifurcation support might be possible but where should the bunch of other protocols the M.2 standard allows for should come from if the slot is only connected to RK3588’s PCIe 3.0 controller?