4 ms·

It's not the usb c committee problem, the devices you are buying are out of spec This is because the cable is 2 sided so it can't assume polarity So it's a tr

by Iulioh 1y ago

It's not the usb c committee problem, the devices you are buying are out of spec This is because the cable is 2 sided so it can't assume polarity So it's a tradeoff for not having to guess how to insert the cable

rcxdude 1y ago
>This is because the cable is 2 sided so it can't assume polarity Not really. The USB-C connection pinout is symmetric about a 180 degree rotation, at least as far as power connections go. It's entirely possible (and common, e.g. when using passive converters) to just put power out of it constantly. The main reason for the signaling resistors is to avoid having power presented on the pins when it's not connected, which is more about avoiding corrosion or wear due to small sparks on connection.
- danhor 1y ago
  And to avoid having two sources (perhaps with slightly different voltages) connected together and leading to hijinks. E.g. a usb A-C cable plugged into a USB-C power supply.
- degamad 1y ago
  By 2-sided, OP probably means that the problem is that the cable has two USB-C ends, not that the USC-c connector is symmetric. If you have an A end and a B or C end, you can assume that the device on the A end is supplying power and the device on the B or C end is consuming power without breaking anything. The A end cannot supply power to it's device by design, so an A to C cable cannot be used to power the A device from the C device, regardless of whether the device on the C end can supply power. But if you have two C ends, you need some way to establish which device is the supply device and which is the consuming device, because the cable can be used to connect two devices which both can supply power (e.g. a laptop and a phone).
Findecanor 1y ago
> This is because the cable is 2 sided so it can't assume polarity To clarify (and to tell my own tale on the topic): The power pins on both sides should be connected in both a plug and in a socket. However, when it comes to the USB 2.0 data pins only the socket end must be double-sided (short A6 to B6 and A7 to B7). Back when "Type C" was new, I wanted to build a project with it, so I got one of the first socket breakout boards available. I built a mechanical keyboard out of aluminium with a slot milled to fit that breakout board. After everything was painted and soldered did I plug it in and it did not work ... It took me a while of troubleshooting before I retried it with the cable plugged in the other orientation. The breakout board had connected only A6/A7. B6/B7 were not available.

by Iulioh 1y ago

rcxdude 1y ago

>This is because the cable is 2 sided so it can't assume polarity Not really. The USB-C connection pinout is symmetric about a 180 degree rotation, at least as far as power connections go. It's entirely possible (and common, e.g. when using passive converters) to just put power out of it constantly. The main reason for the signaling resistors is to avoid having power presented on the pins when it's not connected, which is more about avoiding corrosion or wear due to small sparks on connection.

danhor 1y ago
And to avoid having two sources (perhaps with slightly different voltages) connected together and leading to hijinks. E.g. a usb A-C cable plugged into a USB-C power supply.
degamad 1y ago
By 2-sided, OP probably means that the problem is that the cable has two USB-C ends, not that the USC-c connector is symmetric. If you have an A end and a B or C end, you can assume that the device on the A end is supplying power and the device on the B or C end is consuming power without breaking anything. The A end cannot supply power to it's device by design, so an A to C cable cannot be used to power the A device from the C device, regardless of whether the device on the C end can supply power. But if you have two C ends, you need some way to establish which device is the supply device and which is the consuming device, because the cable can be used to connect two devices which both can supply power (e.g. a laptop and a phone).

Findecanor 1y ago

> This is because the cable is 2 sided so it can't assume polarity To clarify (and to tell my own tale on the topic): The power pins on both sides should be connected in both a plug and in a socket. However, when it comes to the USB 2.0 data pins only the socket end must be double-sided (short A6 to B6 and A7 to B7). Back when "Type C" was new, I wanted to build a project with it, so I got one of the first socket breakout boards available. I built a mechanical keyboard out of aluminium with a slot milled to fit that breakout board. After everything was painted and soldered did I plug it in and it did not work ... It took me a while of troubleshooting before I retried it with the cable plugged in the other orientation. The breakout board had connected only A6/A7. B6/B7 were not available.