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I think this is a stupid thing. Repurposing a commonly used connector for other things to reuse cheap connectors and cables is something that is usually done in

I think this is a stupid thing. Repurposing a commonly used connector for other things to reuse cheap connectors and cables is something that is usually done in the electronic industry (e.g. my oscilloscope use an HDMI socket for the logic analyzer input, you have plenty of lines and the connector is cheap and good). It's not uncommon to design a board and use type-C only for power (5V input, without the circuitry to handle power delivery, so you must connect a suitable power supply) or for other things (TTL serial data). > Fake USB-C cables like Nintendo's that have the right shape but do not adhere to spec should gradually disappear along with lightning cables Which spec? There are a multitude of them! What we do, adhere all to the best spec and to only feed 5V power to a device (that could be done with 2 wires) require the same cable used to connect a thunderbolt device at 40Gb/s? Of course not, since the first one costs a couple of dollars, the second one tens of dollars, the first one can be as long as voltage drop permits it to be, the second one needs to be maximum 1 meter, the first one needs no shielding at all, the second one needs to be heavily shielded, that not only increases cost but makes it bulkier. And again, does a data cable that is used for thunderbolt connection (assuming that the thunderbolt device is externally powered) be designed to carry the full 5A of the spec? 5A is a lot of current, it will require bigger conductors, but for a data cable it doesn't make sense! Type-C is a standard that makes to me not a lot of sense: they wanted to create the one connector that fits all, while in the past they designed different connector, one for each device, not because they wanted you to buy more cables but to avoid confusion in customers, if the cable fits it works I used to say back in the day, the VGA connector was physically different from a serial port, the PS2 connector was not the same as a parallel port, even if they could have done everything with one port they didn't.

deleted 4y ago
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groby_b 4y ago
> Of course not, since the first one costs a couple of dollars, the second one tens of dollars, Of course yes. If the industry was stupid enough to put all of this behind a single plug, then single cable it is. Because pretty much every consumer who has more than one USB3/C cable is dead tired of "oh. This combo doesn't work, let me root for the other cables" Play stupid games, win stupid prizes.
danhor 4y ago
The lowest spec for cables requires 5 wires (CC, 2 * USB 2.0, GND, PWR) and a rating of 3A. CC pins are required for USB-C, if they're left out most devices won't charge over it [1]. 3A is (in my opinion) a reasonable choice, since pre-USB-C devices took up to 2.1A and backwards compatibility is important. USB 2.0 data lanes aren't required for charging per-se, but the older charging protocols preceding USB-C did signalling of the allowed current over the USB 2.0 data lines (otherwise, only 100 mA is allowed). If you want to build a board, compatible with all USB-IF certified chargers and cables and all USB-PD power supplies, that only takes 5 V, the circuitry is two resistors. BOM is always important and stuff, but two resistors is as cheap as it gets. If you just throw it on a board and don't even bother to do a 2 minute google search, I'd take that as an indicator of the effort behind the rest of the board. If it's obvious that it's not a "real" usb-c connector, deviations are reasonable IMHO (for example, a high speed scope connector or a port labelled "debug" on measurement equipment), but for power it's a bad idea. Some products use a "USB-C" power supply putting out 12V all the time (frying other devices connected to it) or save on the 2 resistors, leading to a lot of user confusion when devices will only work with USB-A to USB-C cables. To the latter point: Doubt it. HDMI has tried to include Ethernet (with optional data wires), which luckily was a huge failure (almost no one implemented it). DisplayPort was trying to become USB-C before USB became USB-C. Ethernet now often doubles as a power supply. SD card slots could serve as an additional periphery slot in PDAs with SDIO. The only port common on a modern laptop that didn't (at least try) to include some completely other feature is probably the 3.5mm headphone socket (probably since there is no standard committee and even agreeing on how the 4 pin extension should work was a huge mess). [1] The CC line is needed to determine which device is a power sink & power source. Otherwise, users might connect two 5V power supplies together and create a short (between probably 5.2V & 4.8V)
- kanetw 4y ago
  The 2 resistor on CC line thing is not spec compliant. E: you also need vRd sensing to determine the available current.

deleted 4y ago

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groby_b 4y ago

> Of course not, since the first one costs a couple of dollars, the second one tens of dollars, Of course yes. If the industry was stupid enough to put all of this behind a single plug, then single cable it is. Because pretty much every consumer who has more than one USB3/C cable is dead tired of "oh. This combo doesn't work, let me root for the other cables" Play stupid games, win stupid prizes.

danhor 4y ago

The lowest spec for cables requires 5 wires (CC, 2 * USB 2.0, GND, PWR) and a rating of 3A. CC pins are required for USB-C, if they're left out most devices won't charge over it [1]. 3A is (in my opinion) a reasonable choice, since pre-USB-C devices took up to 2.1A and backwards compatibility is important. USB 2.0 data lanes aren't required for charging per-se, but the older charging protocols preceding USB-C did signalling of the allowed current over the USB 2.0 data lines (otherwise, only 100 mA is allowed). If you want to build a board, compatible with all USB-IF certified chargers and cables and all USB-PD power supplies, that only takes 5 V, the circuitry is two resistors. BOM is always important and stuff, but two resistors is as cheap as it gets. If you just throw it on a board and don't even bother to do a 2 minute google search, I'd take that as an indicator of the effort behind the rest of the board. If it's obvious that it's not a "real" usb-c connector, deviations are reasonable IMHO (for example, a high speed scope connector or a port labelled "debug" on measurement equipment), but for power it's a bad idea. Some products use a "USB-C" power supply putting out 12V all the time (frying other devices connected to it) or save on the 2 resistors, leading to a lot of user confusion when devices will only work with USB-A to USB-C cables. To the latter point: Doubt it. HDMI has tried to include Ethernet (with optional data wires), which luckily was a huge failure (almost no one implemented it). DisplayPort was trying to become USB-C before USB became USB-C. Ethernet now often doubles as a power supply. SD card slots could serve as an additional periphery slot in PDAs with SDIO. The only port common on a modern laptop that didn't (at least try) to include some completely other feature is probably the 3.5mm headphone socket (probably since there is no standard committee and even agreeing on how the 4 pin extension should work was a huge mess). [1] The CC line is needed to determine which device is a power sink & power source. Otherwise, users might connect two 5V power supplies together and create a short (between probably 5.2V & 4.8V)

kanetw 4y ago
The 2 resistor on CC line thing is not spec compliant. E: you also need vRd sensing to determine the available current.