3 ms·

That seems like it should work, although it is a different (and better) proposal than what I had. Essentially, your proposal is to have the invariant that male

That seems like it should work, although it is a different (and better) proposal than what I had. Essentially, your proposal is to have the invariant that males supply power on pin 20 and source on pin 21, while females supply on 21 and source on 20. It is easy to see that this invariant is maintained by all of your proposed cables. And, since the only way to plug ports together is male-female you are guaranteed to always be matching supply with source. Since this invariant is maintained at every terminal, there is, as you identify, no added difficulty in creating converters, as they would only target one gender of the port anyway. Out of curiosity, is there any port that takes this approach (either for power or data pins)?

cesarb 8y ago
"Traditional" USB does that: USB-A ports source power, USB-B ports sink power. (Also, USB-A ports are always towards the host, which controls the bidirectional serial link.) The standard cable has a USB-A plug on one end, and a USB-B plug on the other end. There can be no USB-A to USB-A (or USB-B to USB-B) cable, since they're forbidden by the standard, so you can't connect two sources (or two sinks) together. And of course it didn't work: there are many standard-breaking USB cables with identical plugs on both ends, and standard-breaking devices which require them.
- DSMan195276 8y ago
  That's not quite what I described. With my design either port can source or sink power, they just do it on opposite pins. And it wouldn't be USB-A vs USB-B, but male vs female So for USB, you would need a 5-pin port, where two are devoted to power. And both USB-A and USB-B would have the same wiring, but male ports source and supply on opposite pins as the female ones. Then M-M or F-F cables crossover the power lines.