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Why doesn't the Apple-supplied USB charging cable work?

by Siecje 10y ago

cpmsmith 10y ago
Not all USB-C connectors are created equal. Something with that connector can support or not support a number of protocols, e.g. USB, Thunderbolt 3, USB-C power throughput, etc.
- wlesieutre 10y ago
  In this case, the cable used with the monitor needs to be a Thunderbolt 3 cable, not just a USB-C cable. I haven't seen a teardown of the new ones, but at least for the previous generation there's a bit more to it than your average cable. https://www.wired.com/2011/06/thunderbolt-cable-teardown-reveals-enough-chips-to-make-a-computer/ https://www.wired.com/2011/06/thunderbolt-cable-teardown-rev... Thunderbolt 2 had the same compatibility issue in that it was the same connector as Mini DisplayPort but couldn't run over a standard DP cable. That was pretty minor since it's not like everyone has a pile of loose DP cables sitting around. On the other hand, your average consumer never uses a Thunderbolt device to begin with on account of them being significantly more expensive than other accessories. They'll likely never run into this even with it using a USB-like cable, and the people who do need TB will figure it out.
  - otterley 10y ago
    It's not a Thunderbolt issue. It's about supporting "DisplayPort Alternate Mode." This particular monitor doesn't support Thunderbolt.
    - wlesieutre 10y ago
      Oh interesting, I didn't think monitors could run video over the USB cable and still offer a USB hub on the same connection, but it looks like the DisplayPort data goes over the additional USB-3 lines and preserves the original USB-2 connection for accessories. Good to know. Thunderbolt displays can do hubs at full speed, the 5K LG Ultrafine has 3x USB 3.1 gen 1, which IIRC means up to 5 Gbps (vs 480 Mbps for USB 2). Not sure why your comment was marked [dead] but I just vouched it so it should be back.
lvh 10y ago
The cable is a USB-C cable, but not a Thunderbolt 3 cable. This is confusing, because they use the same USB-C port. My understanding is that Thunderbolt cables have the thunderbolt logo on them.
- otterley 10y ago
  It's not a Thunderbolt issue. It's about supporting "DisplayPort Alternate Mode." This particular monitor doesn't support Thunderbolt.
deleted 10y ago
[deleted]
illumin8 10y ago
It's for charging only. This seems to be a huge disadvantage to USB-c... you have to buy different cables for different purposes, even though they have the same physical connector. Can you imagine if AC power had the same plug for both 110V and 220V? And you just had to "guess" which one was the right one?
- revelation 10y ago
  They do? https://en.wikipedia.org/wiki/IEC_60320 https://en.wikipedia.org/wiki/IEC_60320 That's a common problem with power supplies that require setting a hard switch to choose between 110V and 220V.
  - throwanem 10y ago
    Which is why it's rare at best to encounter such power supplies in new manufacture, and has been for quite some years now. Instead, they sense the line voltage and configure themselves accordingly. It's hard to see the profusion of semi- and incompatibilities permissible in the USB-C connector as anything but a regression.
  - mitchty 10y ago
    Yep, I bought some fun electronic bench gear, on the back it says validate the 110/220/240 setting prior to use. On that note, always look on the back for a manual switch. Just to be safe. Its unlikely a regular consumer would need to but I'm learning to change my habits.
  - schoen 10y ago
    For the socket side of the same problem, see https://en.wikipedia.org/wiki/Mains_electricity_by_country https://en.wikipedia.org/wiki/Mains_electricity_by_country and search for "Power cords with type A or B plugs which are rated at only 125 V may present a safety hazard" (each of the seven occurrences reflects a country that always or sometimes uses U.S.-style sockets with a higher voltage such as 240 V).
lnanek2 10y ago
It probably lacks data lines. It is common for USB cables used for charging to only have power lines and skip the data lines to save money. I believe the USB cable that came with my Chromecast is the same.
- ProZsolt 10y ago
  It has data line, but only supports USB 2.0
pikhq 10y ago
A given USB Type C cable can be a "USB 2.0" cable, which is only good for USB @ 480 Mbps and power, or a "USB 3.1" cable, which can handle USB @ 10 Gbps and power, as well as alternate data modes like DisplayPort or Thunderbolt. Additionally, it can be only good for 3 A, or it can have a chip in it to indicate it's good for more power (up to 5A). The Apple-supplied cable is probably a USB 2.0 cable, with a chip indicating it can handle 5A.
Skunkleton 10y ago
Even worse, you can't expect thunderbolt 3 to work over any cable length. So unless all USB C cables become active cables (unlikely), longer USB C cables won't have thunderbolt support due to signal integrity limitations.

Why doesn't the Apple-supplied USB charging cable work?

by Siecje 10y ago

Why doesn't the Apple-supplied USB charging cable work?

Not all USB-C connectors are created equal. Something with that connector can support or not support a number of protocols, e.g. USB, Thunderbolt 3, USB-C power throughput, etc.

wlesieutre 10y ago
In this case, the cable used with the monitor needs to be a Thunderbolt 3 cable, not just a USB-C cable. I haven't seen a teardown of the new ones, but at least for the previous generation there's a bit more to it than your average cable. https://www.wired.com/2011/06/thunderbolt-cable-teardown-reveals-enough-chips-to-make-a-computer/ https://www.wired.com/2011/06/thunderbolt-cable-teardown-rev... Thunderbolt 2 had the same compatibility issue in that it was the same connector as Mini DisplayPort but couldn't run over a standard DP cable. That was pretty minor since it's not like everyone has a pile of loose DP cables sitting around. On the other hand, your average consumer never uses a Thunderbolt device to begin with on account of them being significantly more expensive than other accessories. They'll likely never run into this even with it using a USB-like cable, and the people who do need TB will figure it out.
- otterley 10y ago
  It's not a Thunderbolt issue. It's about supporting "DisplayPort Alternate Mode." This particular monitor doesn't support Thunderbolt.
  - wlesieutre 10y ago
    Oh interesting, I didn't think monitors could run video over the USB cable and still offer a USB hub on the same connection, but it looks like the DisplayPort data goes over the additional USB-3 lines and preserves the original USB-2 connection for accessories. Good to know. Thunderbolt displays can do hubs at full speed, the 5K LG Ultrafine has 3x USB 3.1 gen 1, which IIRC means up to 5 Gbps (vs 480 Mbps for USB 2). Not sure why your comment was marked [dead] but I just vouched it so it should be back.

lvh 10y ago

The cable is a USB-C cable, but not a Thunderbolt 3 cable. This is confusing, because they use the same USB-C port. My understanding is that Thunderbolt cables have the thunderbolt logo on them.

otterley 10y ago
It's not a Thunderbolt issue. It's about supporting "DisplayPort Alternate Mode." This particular monitor doesn't support Thunderbolt.

deleted 10y ago

[deleted]

illumin8 10y ago

It's for charging only. This seems to be a huge disadvantage to USB-c... you have to buy different cables for different purposes, even though they have the same physical connector. Can you imagine if AC power had the same plug for both 110V and 220V? And you just had to "guess" which one was the right one?

revelation 10y ago
They do? https://en.wikipedia.org/wiki/IEC_60320 https://en.wikipedia.org/wiki/IEC_60320 That's a common problem with power supplies that require setting a hard switch to choose between 110V and 220V.
- throwanem 10y ago
  Which is why it's rare at best to encounter such power supplies in new manufacture, and has been for quite some years now. Instead, they sense the line voltage and configure themselves accordingly. It's hard to see the profusion of semi- and incompatibilities permissible in the USB-C connector as anything but a regression.
- mitchty 10y ago
  Yep, I bought some fun electronic bench gear, on the back it says validate the 110/220/240 setting prior to use. On that note, always look on the back for a manual switch. Just to be safe. Its unlikely a regular consumer would need to but I'm learning to change my habits.
- schoen 10y ago
  For the socket side of the same problem, see https://en.wikipedia.org/wiki/Mains_electricity_by_country https://en.wikipedia.org/wiki/Mains_electricity_by_country and search for "Power cords with type A or B plugs which are rated at only 125 V may present a safety hazard" (each of the seven occurrences reflects a country that always or sometimes uses U.S.-style sockets with a higher voltage such as 240 V).

lnanek2 10y ago

It probably lacks data lines. It is common for USB cables used for charging to only have power lines and skip the data lines to save money. I believe the USB cable that came with my Chromecast is the same.

ProZsolt 10y ago
It has data line, but only supports USB 2.0

pikhq 10y ago

A given USB Type C cable can be a "USB 2.0" cable, which is only good for USB @ 480 Mbps and power, or a "USB 3.1" cable, which can handle USB @ 10 Gbps and power, as well as alternate data modes like DisplayPort or Thunderbolt. Additionally, it can be only good for 3 A, or it can have a chip in it to indicate it's good for more power (up to 5A). The Apple-supplied cable is probably a USB 2.0 cable, with a chip indicating it can handle 5A.

Skunkleton 10y ago

Even worse, you can't expect thunderbolt 3 to work over any cable length. So unless all USB C cables become active cables (unlikely), longer USB C cables won't have thunderbolt support due to signal integrity limitations.