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XKCD
XKCD
05:12
You don't want the nitrogen percentage to be too high or you run the risk of eutrophication.
 
16 hours later…
misk94555
misk94555
20:51
Can I use an Ethernet cable for USB?
Say I have some shreds of USB cables, and a few meters of Ethernet cable. I can [franken]solder USB plugs into the Ethernet cable.
Will the resulting jank work as a USB cable? Low speed (LS, 1.5 Mbps), or high speed (HS, 12 Mbps)?
[It’s a “what if” questions. But I’m hoping that the SuperUser contingent have done so much janky/kludgey stuff that they may know the answer. ]
Criggie
Criggie
heheh yes you can use "any random wire" as a cable.
But USB is known to get snitty at short distances. Even good USB ports+devices+cables can have issues above 2 ~ 5 metres.
@misk94555 Given how cheap and common USB cables are, its probably faster to find a useful one.
The only time I'd bother making somehting is if I need a weird thing, like a USB cable that pases through a 7mm hole and I can't enlarge it. But even then I'd probably enlarge it and slap on some covers.
So - is your spare time so numerous? Can you afford for it to kinda-sorta work and then fail in 5 mins ?
misk94555
misk94555
21:26
@Criggie My challenge is akin to your 7mm hole challenge. I need to penetrate a USB cable into a pressure chamber. I found penetration connectors for Ethernet, so I wonder how much abuse USB can take.
An off the shelf USB penetration connector has a $600 price tag, and I can’t afford it. Ethernet penetration connector [with an acceptable level of kludgeness] costs around $10.
Criggie
Criggie
21:51
ooooo okay - what pressure differential are you expecting to see ?
Is USB the only option? Some kind of wireless solution would be perfect (assuming you can have power inside the pressure chamber
thinking
user image
would let you use the Ethernet bit to go through the wall, and re-convert to USB
Now, if you did the same thing with an RJ45 plug on each end, it might be short enough to Just Work
You say USB1 is adequate at 1.5 Mbit? I guess its some kind of sensor not a high-volume data link ?
@misk94555 Imma go to the garage and try this....
Criggie
Criggie
22:43
Making progress - but I forgot to account for rollover int he RJ45 joiner.
@misk94555 yep that works....
2025-01-10T11:52:10.129277+13:00 thionite kernel: [169800.814554] sd 5:0:0:0: [sdf] 2000409264 512-byte logical blocks: (1.02 TB/954 GiB)
misk94555
misk94555
Wow. What's the model of the USB to RJ45 adapter?
Criggie
Criggie
Though throughput is shit
Timing buffered disk reads: 30 MB in 3.02 seconds = 9.93 MB/sec
misk94555
misk94555
@Criggie The pressure difference will be 1 or 2 atmospheres.
Criggie
Criggie
user image
misk94555
misk94555
@Criggie It will be sensors connected through USB to UART adapters (FTDI). Four adapters plus a hub (or maybe a quad UART-to-USB bridge). Each UART will be at 115.2kbaud.
Criggie
Criggie
22:58
So that was a plain USB2 extension cable, but I cut it in the middle and crimped on some RJ45 plugs
That lets you use the cheaper RJ45 ethernet penetration coupler.
Things that will help it go "better" would be keep the cable as short as possible.
misk94555
misk94555
@Criggie 9.93 MByte or Mbit per second ?
Even 9.93 Mbit will work for what I'm trying to do.
Criggie
Criggie
The foil/braid line on the outside of the USB cable should be on a pin - I suspect I didn't have good contact on that one line using only a few strands.
megabytes/second on a disk read. 
 root@thionite:~# hdparm -t /dev/sdf
 /dev/sdf:    Timing buffered disk reads:  30 MB in  3.02 seconds =   9.93 MB/sec
The other option - 2 atmospheres isn't a lot, that's about 30 PSI, or roughly the pressure of a car tyre.
We have silastics and patches that can hold those pressures. Even a rubber grommit mnight be enough as long as the hole is small.
misk94555
misk94555
23:23
@Criggie Thank you for this experiment!
I'll go ahead and use Ethernet penetrations for USB. I'll post my results here, although it will take a while.

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