4 ms·
I've had a phone like this - it'd increase current until voltage start to sag. It was horrible. Never again. The difference between high-current and low-curren
by theamk 1y ago
I've had a phone like this - it'd increase current until voltage start to sag. It was horrible. Never again.
The difference between high-current and low-current cable was very small, so once cable got a little bit worn out, the detection was basically random. You plug cable, and get 1A charge. Unplug-replug, and it's 0.5A now. Unplug-replug and it gets 2A.
I am very glad that the system has died out and we have cables that simply report their capacity directly.
(that said yes, it could have been simpler, like having a symmetric pinout. But this would be a marginal improvement at best, as USB-IF seems to be incapable of producing simple designs. It'd still be thousands of pages of docs)
- userbinator 1y agoYou just had a bad implementation. cables that simply report their capacity directly. ...which won't true when worn or the manufacturer is lying.
- theamk 1y agoI don't think it is possible to have "good implementation" of cable impedance sensing, given the inherent properties of the connectors. Wetting current is a thing, after all, and it can be quite big for work connectors. Cable-reported capacity does not really change over cable lifetime - the currents used to sense resistance are miniscule, and would not be affected by cable being worn. For example, extra 0.5 ohm of cable resistance completely ruins the current sensing, but make absolutely no difference when measuring 5K or 1K resistance. And if manufacturer is lying, that's annoying but it's 100% deterministic - you know the cable is bad, you can throw it away. With impedance sensing, the same cable can be good or bad, depending on the mood, and that's why it should not be used ever.