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USB Cheat Sheet

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Re: USB Cheat Sheet

#31

Post by birktj »

CoastalCoder wrote: post #27
can16358p wrote: post #20

So on the next versions of USB, the cable length will get shorter and shorter until the max gets to 5cm? While I get the technical reasoning about high frequency/attenuation etc that limits cable length as speeds go higher, there are obviously some practical limits to how short cables can be. How would that be solved, I don't know.

Not my area of expertise, but maybe some (unrealistic) options include using fiber optics for the data lines, or adding more data lines.

There already exists some fiber-optic USB cables that come in lengths >50m and with support for USB 3.1 so it doesn't seem like a very unrealistic option.

Re: USB Cheat Sheet

#32

Post by Tepix »

dschuetz wrote: post #19

So where exactly does USB-C fall into? I have 2 different generations of USB-C hosts, and they behave quite differently when approaching max cap, especially with high-quality low-latency audio (USB-C was supposed to be de-facto replacement for FireWire).

Good question. I bought a RaidSonic Icy Box IB-1121-C31 USB 3.1 (10Gbit) S-ATA dock recently (with a USB Type C connector) that came with a USB C cable and had a buy a special "USB-A - USB type C cable" to achieve 10Gbit/s with the 10GBit/s USB A connector of my mainboard.

The "USB A - USB type C cables" that i had already only worked up to 480MBit/s.

Re: USB Cheat Sheet

#33

Post by microtonal »

LeonidasXIV wrote: post #23
dschuetz wrote: post #19

So where exactly does USB-C fall into? I have 2 different generations of USB-C hosts, and they behave quite differently when approaching max cap, especially with high-quality low-latency audio (USB-C was supposed to be de-facto replacement for FireWire).

USB-C is a connector type, like USB-A (usually known as the classic USB plug) and USB-B (usually the other side of said plug, a square kind of connector). USB-B had other offspring like miniUSB and microUSB (note that in these cases on the other side of the cable you usually have a USB-A plug). USB-C is the first time cables have the same connector on both sides, so it obsoletes USB-A and USB-B. But what is sent over…

Can be USB 3 [...] USB 2, so it is a bit hard to tell.

...or Thunderbolt, USB 4, DisplayPort (through Alt-mode or encapsulated in Thunderbolt), or HDMI (Alt-mode), or MHL (Alt-mode), USB Power Delivery...

Unfortunately, not every cable with USB-C connectors can carry all of these. E.g. there are USB-C cables that can only carry USB 2. Or cables that can carry USB 3, but not Thunderbolt. Also, not all cables can carry the same wattage for power delivery.

It's a mess.

Re: USB Cheat Sheet

#34

Post by dual_dingo »

CoastalCoder wrote: post #27
can16358p wrote: post #20

So on the next versions of USB, the cable length will get shorter and shorter until the max gets to 5cm? While I get the technical reasoning about high frequency/attenuation etc that limits cable length as speeds go higher, there are obviously some practical limits to how short cables can be. How would that be solved, I don't know.

Not my area of expertise, but maybe some (unrealistic) options include using fiber optics for the data lines, or adding more data lines.

I guess at some point optical will be the only way forward.

Having more data lines in a serial bus is interesting, as the whole reasoning to go from parallel lines (e.g. Centronics, ATA/SCSI or ISA/PCI buses) to serial (SATA/SAS, PCIe, USB) was that coordinating multiple data lines got impossible due to physical limitations where e.g. minimal differences in cable lengths started to matter).

Re: USB Cheat Sheet

#35

Post by TonyTrapp »

_joel wrote: post #24

I've definitely used 5m+ extensions on USB1 (and 2 iirc) before. I guess it'd be sketchy running something that requires decent throughput and not b0rk on ECC/FEC/whatever it uses but for temperature sensors which I was using, it was fine.

A long time ago, I was using a USB 1 or 2 Wifi adapter through a USB extension cord, I'm pretty sure the total cable length was more than 5 meters. It "worked", but even just flicking a light switch caused the network connection to reset. So yeah, it may "work", for certain values of "work".

Re: USB Cheat Sheet

#36

Post by Chilinot »

birktj wrote: post #31
CoastalCoder wrote: post #27

Earlier quoted context omitted.

Not my area of expertise, but maybe some (unrealistic) options include using fiber optics for the data lines, or adding more data lines.

There already exists some fiber-optic USB cables that come in lengths >50m and with support for USB 3.1 so it doesn't seem like a very unrealistic option.

That sounds more like fiber optic adapters/converters that fit into usb-ports and talk usb, rather than USB-cables that can be 50+ meters.

Re: USB Cheat Sheet

#37

Post by rob74 »

microtonal wrote: post #33
LeonidasXIV wrote: post #23

Earlier quoted context omitted.

USB-C is a connector type, like USB-A (usually known as the classic USB plug) and USB-B (usually the other side of said plug, a square kind of connector). USB-B had other offspring like miniUSB and microUSB (note that in these cases on the other side of the cable you usually have a USB-A plug). USB-C is the first time cables have the same connector on both sides, so it obsoletes USB-A and USB-B. But what is sent over…

Can be USB 3 [...] USB 2, so it is a bit hard to tell. ...or Thunderbolt, USB 4, DisplayPort (through Alt-mode or encapsulated in Thunderbolt), or HDMI (Alt-mode), or MHL (Alt-mode), USB Power Delivery... Unfortunately, not every cable with USB-C connectors can carry all of these. E.g. there are USB-C cables that can only carry USB 2. Or cables that can carry USB 3, but not Thunderbolt. Also, not all cables can carry…

Of course USB-C makes this worse, but the problem already started earlier: a few years ago I connected my phone to my computer with a USB-A to micro USB cable and was scratching my head why it didn't work. Then I remembered that the cable had come with some Bluetooth headphones and was only a charging cable without data lines...

Re: USB Cheat Sheet

#38

Post by belter »

masklinn wrote: post #10

Some of the entries seem incorrect: "USB 3.2 (USB 3.2 Gen 2x2) and "USB 4" (USB 4 USB4 Gen 2×2) should have the same nominal data rate of 2500MB/s, they're 2 lanes (x2) of 10GB/s. Though they are apparently coded differently electrically, so they're distinct protocols. The tables would benefit from mentioning the coding (8/10 or 128/132) as IMO it's one of the most confusing bits when you see the effective data rates…

Also should be:

12 Mbps -> 1.43 MiB/s -> 1.5 MB/s

480 Mbps -> 57 MiB/s -> 60 MB/s

5000 Mbps (5 Gbps) -> 596 MiB/s -> 625 MB/s

10000 Mbps (10 Gbps) -> 1192 MiB/s -> 1250 MB/s

20000 Mbps (20 Gbps) -> 2384 MiB/s -> 2500 MB/s

40000 Mbps (40 Gbps) -> 4768 MiB/s -> 5000 MB/s

Re: USB Cheat Sheet

#39

Post by formerly_proven »

eugene3306 wrote: post #15

just curious. Can USB3 work without D+ and D- ?

USB 3 and previous standards are completely separate connections and software stacks - the USB 1/2 D+/D- pair does not interact at all with SSRX/SSTX. You should be able to literally cut the D+/D- wires in an USB 3 cable and it should still work as a USB 3 cable.

Re: USB Cheat Sheet

#40

Post by netsharc »

Ah USB. In the old days it was different cables for different things, nowadays it's 1 connector for everything but beware, the cable might physically plug into the socket, but whether you'll get the functionality you want?
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