MrMike
Well-Known Member
+1, USB loses more power per foot than it does add latency. Usually when the cable is the issue, it's just somebody bent the crap out of the end or is using a non-compliant A to C cable.Oh, I'm quite familiar with latency via a conductor, but AA and CarPlay aren't DDR5 DIMM modules running at 8000MT/s needing to be within millimeters of a CPU socket.
Every foot of USB cable introduces a latency of about 1 nanosecond, or a billionth of a second, so a 10-foot cable would be approximately 10 nanoseconds, or a 100,000,000th of a second. That sort of latency would cause bit collisions in computer memory beyond a certain speed, but what Android Auto and CarPlay are doing doesn't have the parallel data bus issues requiring everything being in sync like that. Hell, it's not close to saturing the USB 2.0 spec (which was the only option on an iPhone until last year) let alone coming close to the speed and latency capabilities of USB 3 or USB 4 (which no mobile devices have, yet), but that doesn't matter because the cars only come with USB 2.0 spec ports.
Consider this, though... Both AA and CarPlay can also work wirelessly, which introduces A LOT more latency than that, measuring anywhere from 1.5 to 15 milliseconds!
I'd honestly be more worried about the longevity of a cable because cheap cables are likely to kink and have connectivity issues within their conductors. That's why I went with a six-foot Anker USB A to USB C cable and a quality right-angle connector. I connect mine to the port in the center console, like I said above.
I'd love to know what the supposed latency requirements for AA and CP are that latency times in that range are a concern. A cabled connection would leave the APIM in a wait-state for times imperceptible by human senses. There would have to be a lot of instructions piling up on that wait-state before the human eye can notice any lag (which I'm now using that word since it is different than latency) since the threshold for that is roughly, on average (but not as a rule, see: competitive gamers), 13ms.
My Bronco supports wireless AA/carplay w/wireless charging on Sync 4 which clearly has a bit of lag compared to using wired.
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