3 ms·

My point, which matches what you've written out in more detail, is that there's supposed to be stuff (resistors) in the cable, stuff which is often not there. T

My point, which matches what you've written out in more detail, is that there's supposed to be stuff (resistors) in the cable, stuff which is often not there. There are plenty of these abhorrent cables in the wild. And when you come across one, things get weird, because some sources and sinks deviate from the standard in ways that make them work with these bad cables. Others don't do that. (I believe there were a lot more abhorrent cables in the early days, and thus began the chain of accommodation....) So unless your cable is known-good, if you are having trouble, trying a different cable should be the first thing you do. It really does often get things working. Contrarily, if you have identified a naughty cable, it should be immediately widlarized.

ssl-3 4mo ago
I gathered that you knew that. I'm mostly just trying to complete the picture for those following along at home, who might find some of this resistor business to be a bit weird compared to the USBs of yore. Except the old ways were weird in unseen ways, too. Some combinations of cable, phone, and charger worked well and some barely worked at all. We're in much better shape with USB C and PD. It's generally a good, forward-looking way of doing all kinds of things. I just wish the cables and ports were better-marked, and that manufacturers stopped fucking around by making non-compliant stuff, and that there were a clear way with two battery-equipped USB C devices to unequivocally declare that a particular one will charge the other (and not the other way 'round). And yes: The non-compliant widgets should ideally be named, shamed, and Widlarized -- not simply tolerated or worked around.
SAI_Peregrinus 4mo ago
Resistors don't go in the cable. They go in the device. They indicate that the device can't negotiate voltages above 5V, so just send 5V. USB-A has no ability to provide voltages other than 5V, so there's no need for indicating it's the max. Not all chargers have USB-A ports. Many laptops don't have USB-A ports, so if you want to charge a noncompliant device from a laptop it won't work. Or a laptop charger, which is dedicated USB-C.

ssl-3 4mo ago

I gathered that you knew that. I'm mostly just trying to complete the picture for those following along at home, who might find some of this resistor business to be a bit weird compared to the USBs of yore. Except the old ways were weird in unseen ways, too. Some combinations of cable, phone, and charger worked well and some barely worked at all. We're in much better shape with USB C and PD. It's generally a good, forward-looking way of doing all kinds of things. I just wish the cables and ports were better-marked, and that manufacturers stopped fucking around by making non-compliant stuff, and that there were a clear way with two battery-equipped USB C devices to unequivocally declare that a particular one will charge the other (and not the other way 'round). And yes: The non-compliant widgets should ideally be named, shamed, and Widlarized -- not simply tolerated or worked around.

SAI_Peregrinus 4mo ago

Resistors don't go in the cable. They go in the device. They indicate that the device can't negotiate voltages above 5V, so just send 5V. USB-A has no ability to provide voltages other than 5V, so there's no need for indicating it's the max. Not all chargers have USB-A ports. Many laptops don't have USB-A ports, so if you want to charge a noncompliant device from a laptop it won't work. Or a laptop charger, which is dedicated USB-C.