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patentatt | 2 years ago

I guess that's what we get when a rotary encoder is much much less expensive than a 4-6 gang potentiometer. And I also feel your pain with the car "booting up" phenomenon. I don't even have a particularly tech-heavy vehicle and upon starting the car the entire infotainment system feels like booting up a packard bell in 1996.

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wolrah|2 years ago

> I guess that's what we get when a rotary encoder is much much less expensive than a 4-6 gang potentiometer.

Also a rotary encoder doesn't age in the same way as a potentiometer. A potentiometer can wear out the area being used most heavily while simultaneously developing oxidation on the areas not being used. Eventually this leads to crackling, dead areas on the dial, and other misbehavior.

A rotary encoder on the other hand doesn't wear out in a practical sense. The only part that even could wear is the bearing or bushing supporting the rotating assembly, and if that's specced appropriately for the application it's effectively a lifetime component. It's possible to build a crappy rotary encoder that falls apart earlier than desired, and of course they can still be damaged by abuse, but a well built one should outlast the useful life of the device it's installed in by multiple orders of magnitude.

dreamcompiler|2 years ago

Relative rotary encoders are much cheaper than absolute rotary encoders, and I expect that's the problem here. If the encoders were absolute, one could make them work just like a potentiometer (because potentiometers are absolute). Relative encoders cannot remember where they were last set because they only sense dp/dt, rather than position itself. So it's up to the software to remember the last position, and everybody knows car companies won't pay software engineers tech company salaries, so by definition car companies get B-level and C-level programmers, and the driver gets weird misbehaving audio in the car.

neuralRiot|2 years ago

Rotary encoders do fail, they produce the effect of control being unresponsive or “reversed”

masfuerte|2 years ago

Old school wire-wound potentiometers are nearly indestructible.

toast0|2 years ago

You can't really use a user facing pot for volume control when you've also got volume control buttons on the steering wheel and keywords for voice control.

dreamcompiler|2 years ago

Well you can and some kinds of high-end audio equipment are actually built to do this by putting servo motors on the pots so that settings can be stored and retrieved automatically. But that's probably too expensive for a car company to consider.

Rychard|2 years ago

I can't recall seeing a single car that used a potentiometer for the volume control, and I've had cars from the early 90's all the way to today. They've all used encoders.

Do you have some examples of makes/models that used potentiometers for volume control?

wolrah|2 years ago

> I can't recall seeing a single car that used a potentiometer for the volume control, and I've had cars from the early 90's all the way to today. They've all used encoders.

That's because the switch happened earlier than that. Go back earlier than the "DIN size" head units of the '80s and '90s to the "shaft" style radios with two large knobs flanking a center section with an analog frequency display and maybe some preset buttons if you're lucky.

LorenPechtel|2 years ago

The problem is not a rotary encoder, but how the software handles the signals. That's what interrupts are for, the command should make it into the software queue basically instantly, ensuring commands aren't lost.

brokenmachine|2 years ago

Shut up with your Silicon Valley nerd talk!

Good old reliable polling. That's where it's at. 2 second response for a volume knob should be quick enough for anyone!

martyvis|2 years ago

Is the problem that the same systems are used for car media and potentially other systems and that encoders "can" be more flexible if they need to be?

webworker|2 years ago

Packard bell comment made me laugh :)