this post was submitted on 09 Oct 2023
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You can do cable detection with just a few resistors. Why make everyone use active cables just for basic functionality? Aside from exceptional rare circumstances, consumer grade cables should be passive devices IMO.
They don’t use cable ICs for basic power use. The IC in the cable (different ICs for different capabilities) is used for high power negotiation (ie the cheap thin cable won’t be able to do 100W, and the lack of chip ensures this safety requirement) and also for active equalization do you can get 40Gbps.
It’s a good thing, and cheap cables don’t need it at all. The system falls back safely.
Pull up resistors have solved the same problem much more simply for decades. Even with ICs, manufacturers can still make weak cables that lie about their capacity then burst into flames. The IC is not what making the cable safe, it's the manufacturer. And if all else fails, the host can still directly measure cable resistance with some help from the client.
I mentioned this in another post, but yes, resistor dividers are useful and have been used for ages. However things like component aging/damage and simply having enough headroom between different options limits the number of discrete states you can convey with a resistor divider.
I’m usually not a fan of overcomplicated solutions, but these identity chips aren’t that.