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Why Carmakers Can’t Transition to Newer Chips

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Re: Why Carmakers Can’t Transition to Newer Chips

#261
post #111
post #99

Earlier quoted context omitted.

10K global variables sounds insane, until i realize "oh, huh, we have that too, we just call it _config_". Almost every place we would have a constant (tuning parameters, etc) we instead have a configurable value with the likely default declared in code, but all overridable in config. Managing config can be a hassle, but the number of times we've merely had to tweak a value rather than roll a new build pays for itsel…

I always interpreted the "10K global variables" to mean 10K directly accessible, heap-allocated symbols. It's a code reek. If you use a configuration object or other abstraction, the number of accessible variables may not change, but their scope and access method does. It's a matter of interpretation I guess, but I would not classify a wrapper object (like .Net's ConfigurationManager singleton) as "10K global variabl…

From the article referenced in that earliser discussion: https://www.safetyresearch.net/toyota-unintended-acceleratio...

> Other egregious deviations from standard practice were the number of global variables in the system. (A variable is a location in memory that has a number in it. A global variable is any piece of software anywhere in the system can get to that number and read it or write it.)

However, that was from the article author explaining the testimony, and not the testimony itself. It's not totally clear whether the variables were writable.

I would have guessed they were statically allocated rather than heap allocated, but what really matters is whether they were `const` — and they probably weren't `const` because otherwise this testimony wouldn't have rung true:

> "And in practice, five, ten, okay, fine. 10,000, no, we’re done. It is not safe, and I don’t need to see all 10,000 global variables to know that that is a problem," Koopman testified.

Re: Why Carmakers Can’t Transition to Newer Chips

#262
post #223

Earlier quoted context omitted.

I seem to recall, several years ago (when stopping the engine at traffic lights and restarting as soon as the driver released the brake), at least one company was exploring moving to 24V. However, the effort failed precisely because the lifetime of 24V switches was significantly shorter. Naturally, I can't find any links to the info...

FWIW Almost no switches in a modern car (turn signals, wipers, door switches) carry a significant amount of current as they are controlled via confuzers. Just built a car without a single relay. I used PMUs (basically boxes of mosfets and current sensors AFAIK).

wtf is a confuzer? I can find nothing via Google.

Re: Why Carmakers Can’t Transition to Newer Chips

#264

Earlier quoted context omitted.

> If you were going to design a new car electrical architecture from scratch today, you would have something like a 40-60V system with a centralized controller (or pair of controllers in a safety redundant configuration). Actually this point is something im curious about - it seems to be redundant to have a 3X redundant processor ..probably placed in different places on the car body for safety. Would that not be supe…

Most SpaceX hardware works this way: off-the-shelf processor, triply redundant, using voting to figure out if one is wrong.

SpaceX is definitely pushing the use of off the shelf components, and good on them, but things will probably be different when they are building rockets that they expect to keep in service for ten years.

Re: Why Carmakers Can’t Transition to Newer Chips

#265

But cars don't even need chips. Cars worked just fine for 70 years without chips. I don't get it.

Blame the EPA, California for more aggressive pollution and economy standards. You could still build a 1970s car today without chips, you just couldn’t sell it.

Re: Why Carmakers Can’t Transition to Newer Chips

#266
post #264

Earlier quoted context omitted.

Most SpaceX hardware works this way: off-the-shelf processor, triply redundant, using voting to figure out if one is wrong.

SpaceX is definitely pushing the use of off the shelf components, and good on them, but things will probably be different when they are building rockets that they expect to keep in service for ten years.

Aren’t most rockets, outside of SpaceX’s ones that can land after launching, single use? Then keeping the same rocket going for 10 years would be a problem unique to spaceX unless we count the space shuttle?

Re: Why Carmakers Can’t Transition to Newer Chips

#267
post #262
post #223

Earlier quoted context omitted.

FWIW Almost no switches in a modern car (turn signals, wipers, door switches) carry a significant amount of current as they are controlled via confuzers. Just built a car without a single relay. I used PMUs (basically boxes of mosfets and current sensors AFAIK).

wtf is a confuzer? I can find nothing via Google.

slang for 'computer' made popular by Youtuber AvE

Re: Why Carmakers Can’t Transition to Newer Chips

#268

I'd love to see Ken Sherrif do a teardown of some vintage ECM. https://www.autotrader.com/car-news/when-did-cars-get-comput... (tldr) > So instead of one clear answer, we have three possibilities: 1957 Rambler, 1958 Chrysler or 1968 Volkswagen.

Early electronic fuel injection was pretty shit. https://en.wikipedia.org/wiki/Jetronic No throttle control, cold start compensation with a bimetal strip + heater coil controlling extra air flap. Sensors were super primitive or omitted altogether (no temp sensors), air was measured with turbines restricting flow, no lambda, etc etc.

Crazy Honda fact: all their ECUs from 1992 (P05) onward had full facility to drive individual coil on plug, but officially Honda switched away from mechanical distributor in 1999 (S2000?). You can trivially convert 92 car with a small adapter board, ECUs shipped with all the needed firmware and hardware in place sitting unused for 7 years.

Re: Why Carmakers Can’t Transition to Newer Chips

#269

Earlier quoted context omitted.

> Cost wise, Tesla pretty much still sells car at a loss and relies heavily on carbon offset subsidies for income. I'm sorry but that is just straight up complete nonsense. Like seriously, you are directly disagreeing with public financial statements. We know exactly how much margin Tesla has, with and without carbon offset. The simple fact is, Tesla has leading automotive margins even when you exclude any carbon cre…

Hmm. I'm not sure I'd go strongly either way. According to reports ( https://www.cnn.com/2021/01/31/investing/tesla-profitability... ) Tesla received $1600M in regulatory credits and had a net income of $721M. If you look at the 10K ( https://www.sec.gov/Archives/edgar/data/1318605/000156459021... ), Tesla received $27,236M in automotive revenues (which includes sales of regulatory credits, thanks Elon). The correspo…

Tesla has to deduct the “cost” of issuing new shares for stock compensation like for their CEO. It’s not a cost as in they spent cash, but is deducted because it lowers shareholder value. A better sense of their actual profit/loss is their free cashflow which is positive even after your deduct ZEV credit sales.

Re: Why Carmakers Can’t Transition to Newer Chips

#270

Earlier quoted context omitted.

It is a fundamental problem (it's physics). The current rating for relays drops off sharply as the DC voltage increases; you might see 125 V DC rating, but the current will be a fraction of the nominal current at the rated AC voltage. If you're using an relay rated for up to 250 VAC/DC, then the breaking capacity with DC might be as low as 1 % compared to AC. Bad relay datasheets don't mention this at all, or maybe o…

Speaking of good relay datasheets, some will also show contact resistance vs current. I recall one which noted that for small signals the resistance was very low, but if higher current was applied, the contact coating would burn off and the resistance rises permanently.

Yep, those are gold-over-silver(-over-nickel-on-contact-alloy) plated contacts. Good for both signal and power switching, as long as you use the same relay only for one of those things.
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