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lgeorget 2 hours ago [-]
I lost a good two hours the other day on an insufficiently documented device, looking for a way to flash a new firmware onto it.
dmesg was absolutely silent about it when I plugged in or out my C-C USB cable although the device switched on when I was using a simple charger instead. I opened it up to see if there was a special switch or something to put it in firmware flashing mode, to no avail. The little documentation I had only mentioned using one of the USB port.
In the end, out of ideas, I switched cables (even though I knew my cable was perfectly fine). As soon as I plugged in a A-C USB cables, everything worked immediately...
mort96 29 minutes ago [-]
IMO it's a huge failure of the USB-C standard that to a USB 2 only device, a C-C cable looks different to an A-C cable. It's the cause of so many issues of the kind, "it works when I use a different cable" or "it works with this power supply but not that power supply". I understand why something needs the ability to check, but when not doing anything special to detect USB-C capabilities, they should be identical.
crote 23 minutes ago [-]
> to a USB 2 only device, a C-C cable looks different to an A-C cable
It does not. The vast majority of sinks have absolutely no knowledge of the cable used.
This is literally device engineers not bothering to read any part of the USB-C spec, or intentionally leaving out a $0.0003 part. And no, that's not a typo - I really do mean "50k unit reel for $15".
mort96 1 minutes ago [-]
I know how cheap resistors are. I design PCBs as a hobby and occasionally for money.
Leaving off parts should result in behavior which is identical whether you connect an A-C cable or a C-C cable. Detecting the difference between them should require adding parts.
criddell 2 hours ago [-]
What was the device? Somebody experiencing the same problem might appreciate the tip.
seba_dos1 12 minutes ago [-]
There's all sorts of cheap devices like that out there that merely have a Type C-shaped receptacle that doesn't actually implement Type C because they couldn't bother to place two resistors on the board.
eknkc 2 hours ago [-]
I did not know this was a thing.
I have a couple of devices that do not charge on a usb c source. I have to use a USB A - C cable on their shitty usb-c ports.
Now that I know the probable reason I’m more annoyed.
Cieric 36 minutes ago [-]
Another thing that it could be is quick charge, since that seems to conflict with some PD chargers as they'll try to negotiate, fail and then reset. My Light L16 camera has this problem so I have to use the charger it came with or find something dumb enough that it doesn't try anything special.
rjh29 60 minutes ago [-]
While the device is ultimately to blame, many PD chargers will work anyway (by dangerously assuming 5V when there are no CC resistors). My Anker chargers do this.
8cvor6j844qw_d6 42 minutes ago [-]
Interesting. I thought 5V is a safe default for USB when in doubt and risk of damage is nil even if it's assumed.
seba_dos1 19 minutes ago [-]
Just grab two of these spec-violating chargers and a C-to-C cable.
I don't think the right solution to problems coming from spec-violating garbage is producing differently spec-violating garbage.
Palomides 50 minutes ago [-]
are there devices that are damaged by 5V?
megous 38 minutes ago [-]
There's nothing dangerous about it.
No Type-C receptacle featuring device can assume there will be no Vbus voltage on attachment from the other side, regardless of CC signals.
For a simple reason that USB C-A cable assemblies exist and can be plugged to any old charger or port on the A side, which will not wait or negotiate anything. It will just source Vbus 5V right away.
crote 20 minutes ago [-]
... which is exactly why a source with a female USB-C port is not supposed to apply VBUS until it detects a sink.
Obvious counterpoint: what's going to happen when two noncompliant "always provide 5V" USB-C wall warts are connected together with a C-C cable? How well does a charger like power being fed into it?
joecool1029 1 hours ago [-]
There were some higher profile products that left this out like the original revisions of the raspberry pi 4.
seba_dos1 10 minutes ago [-]
Raspberry Pi 4 had a slightly different problem - they attempted to get away with using just one resistor instead of two, as it allowed them to simplify their voltage-sensing circuit a bit. At a cost of non-compliance and all the issues that came with it, of course, so not a great bet after all.
metaphor 38 minutes ago [-]
Anyone in test for the domain able to attest that formal USB compliance verification would have detected the design defect that this hack resolves?
crote 27 minutes ago [-]
It absolutely would. This is an "didn't even read a 5-paragraph AI summary of the spec" level of a design defect.
If you need this fix, it will literally refuse to work with any spec-compliant USB-C device on the other side of a C-C cable. No way to miss it.
8cvor6j844qw_d6 33 minutes ago [-]
Wonder if there are USB C cable testers that detects this.
In practice, most if not all networking/hardware department carries a ethernet cable tester but somehow not true for USB cables.
seba_dos1 5 minutes ago [-]
You don't need a tester to detect this (and it's not about cables).
rufo 1 hours ago [-]
As someone with a bunch of "USB-C" devices that do this, I'd wondered for years why nobody sold these. I recently just found them on Aliexpress in a more finished format (nice-looking case and such), so I'm hopeful they'll start to filter out into the world more. (If you're interested, do a search for "usb c resistor" and you'll find them for ~$2-$4.)
kevin_thibedeau 1 hours ago [-]
Are you sure they aren't C-to-C data blockers?
The_SamminAter 2 hours ago [-]
Oh, I made one of these not too long ago with those 4-pin solderable aliexpress USB-c pcbs. One side has the resisters, and I just joined them with headers. A few months ago I was looking for something just like this, but couldn’t find anything. I think a pack of 10 male and 10 female ports with CC resistors cost <$10, but I suppose this is a more elegant and accessible solution (plus, may actually pass more lines through).
tbyehl 1 hours ago [-]
Hagibis makes one that isn't a bare PCB. B0GLFGTLW9 on Amazon.com, for me today it's showing $6.99 for a 2-pack.
Congeec 1 hours ago [-]
I don't buy and return products that don't charge with a single usb-c cable. How can I expect good quality from a product if the maker saves on ¢1 cent? It's 2026 yet new products still keep people from going all usb-c.
0x457 18 minutes ago [-]
It's much less than a cent.
megous 32 minutes ago [-]
2 connectors and a 0.01c PCB for the price of a complete working charger.
Ajedi32 4 minutes ago [-]
If you need this, it's not the charger that's broken but the device you're plugging into it.
rahimnathwani 28 minutes ago [-]
You can get five of them for less than $4 total here:
dmesg was absolutely silent about it when I plugged in or out my C-C USB cable although the device switched on when I was using a simple charger instead. I opened it up to see if there was a special switch or something to put it in firmware flashing mode, to no avail. The little documentation I had only mentioned using one of the USB port.
In the end, out of ideas, I switched cables (even though I knew my cable was perfectly fine). As soon as I plugged in a A-C USB cables, everything worked immediately...
It does not. The vast majority of sinks have absolutely no knowledge of the cable used.
This is literally device engineers not bothering to read any part of the USB-C spec, or intentionally leaving out a $0.0003 part. And no, that's not a typo - I really do mean "50k unit reel for $15".
Leaving off parts should result in behavior which is identical whether you connect an A-C cable or a C-C cable. Detecting the difference between them should require adding parts.
I have a couple of devices that do not charge on a usb c source. I have to use a USB A - C cable on their shitty usb-c ports.
Now that I know the probable reason I’m more annoyed.
I don't think the right solution to problems coming from spec-violating garbage is producing differently spec-violating garbage.
No Type-C receptacle featuring device can assume there will be no Vbus voltage on attachment from the other side, regardless of CC signals.
For a simple reason that USB C-A cable assemblies exist and can be plugged to any old charger or port on the A side, which will not wait or negotiate anything. It will just source Vbus 5V right away.
Obvious counterpoint: what's going to happen when two noncompliant "always provide 5V" USB-C wall warts are connected together with a C-C cable? How well does a charger like power being fed into it?
If you need this fix, it will literally refuse to work with any spec-compliant USB-C device on the other side of a C-C cable. No way to miss it.
In practice, most if not all networking/hardware department carries a ethernet cable tester but somehow not true for USB cables.
https://a.aliexpress.com/_mtW11kT