Expansion card speeds

Creators & Developers
1

Not concerned with certification, but don’t understand thunderbolt.
If I use a USB C expansion card, what speeds would I get if connected to a thunderbolt device
What are the speeds of the USB A cards what is the speed of a USB C device.
thanks
dan

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3

If your device ask for USB protocol (rather than Thunderbolt protocol), it will deliver that just fine.

USB3.0(or 3.1, basically the extreme majority of “blue” USB devices) (the protocol) is at 5Gbps. USB3.2 or USB4 I think goes to 10Gbps.

Now, as said. The CPU have baked in USB-4 controllers (realistically, they baked in Thunderbolt controllers which also support USB-4), and they downward support USB 3.2 and among many other things.

So it depend on what you are connecting it to. But I think the port isn’t the one that slow it down. The expansion card more likely just have the USB-A bottleneck, which runs USB3.1 gen 2 at 10Gbps.

4

thanks,
Is Usb 3.1 Gen2 the same as USB 3.2, ? Because from you answer, they both seem to be 10Gbs

dan

5

They are essentially 40Gbps. USB4 is essentially Thunderbolt 4 which is essentially just more streamlined Thunderbolt 3 which is 40 Gbps.

7

The Framework Laptop expansion cards use Thunderbolt 4/USB4.

That means it can do USB 1.1, USB 2.0, USB 3.0, USB 3.1 gen 2, USB4, Thunderbolt 1/2/3/4, DisplayPort 1.1, 1.2, 1.3, 1.4.

  • USB 3.0 is USB 3.1 gen 1 or USB 3.2 gen 1x1. 5 Gbps.
  • USB 3.1 gen 2 is USB 3.2 gen 2x1. 10 Gbps. This is the limit for USB type A.
  • USB 3.2 adds USB 3.2 gen 2x2. 20 Gbps. It is optional for USB4. It is not included with Intel’s Thunderbolt 4/USB4 controllers.
  • USB4 adds USB4 gen 2x1 (10 Gbps), USB4 gen 2x2 (20 Gbps), USB4 gen 3x1 (20 Gbps), and USB4 gen 3x2 modes (40 Gbps). These USB4 modes are different than USB 3.x since they support tunnelled USB 3.x, tunnelled DisplayPort, tunnelled PCIe, and other data such as Thunderbolt IP for macOS/Windows/Linux.
    • Thunderbolt is optional for USB4. Of course Intel’s Thunderbolt 4 controllers support both USB4 and Thunderbolt. Thunderbolt timing (10.3125 Gbps or 20.625 Gbps) is slightly different than USB4 timing. USB tunnelling is new with Thunderbolt 4/USB4. PCIe and DisplayPort tunnelling and Thunderbolt IP originated with Thunderbolt 1. Arbitrary types of data (not tunnelled USB/PCIe/DisplayPort) similar to Thunderbolt IP can be sent between two hosts: macOS has Thunderbolt Target Disk Mode and Thunderbolt Target Display Mode for example. Target Disk Mode is interesting because the source is a EFI driver (only exists in Mac firmware) while the sink is a macOS driver. Thunderbolt Target Display Mode uses a macOS source driver and the sink driver is also in macOS but only works on certain old iMacs.

For DisplayPort tunnelling, it’s possible to do two DisplayPort connections (two displays or one dual tile display like the LG UltraFine 5K) over Thunderbolt/USB4. Intel discrete Thunderbolt controllers are limited to two - that’s how many DisplayPort inputs they have. Maybe more could be supported with future USB4 controllers. I don’t know what happens with eGPUs like the Black Magic eGPU or Sonnet Puck 5500 XT or 5700 which also have a Thunderbolt controller with two DisplayPort inputs - if you connected one of those, then maybe you could have 4 DisplayPort connections on the same Thunderbolt cable (two from the host GPU and two from the eGPU).

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8

thanks,
good explanation including some that is over my head
dan

10

True, but you must use the USB-C plug to get any
device to deliver those speeds. Isn’t that correct?

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