Tesla Flash Memory

[Zoomer]

Flash is a wear item.

In a automotive context a wear item is designed to be replaced at nominal intervals. This eMMC chip is ball-grid soldered to the motherboard, inaccessible without disassembling the dash, and not specifically mentioned in the owner’s manual.

 

[chris719]

Probably true, but the point remains. Large capacity flash memory in a vehicle's infotainment display system should be replaceable in a straighforward manner, without needing a recall, and a whole lot (~135,000) of scrapped displays/boards etc. Personally, I think 5-7 years isn't too bad, IF the flash ram was easy to replace.

You have no doubt inspected the internals of ECUs and other vehicle systems. The components used are often absolutely bog standard silicon with the only real differences being the quality of the board, soldering, casework and prevention of environmental ingress. I've seen car audio built better than vehicle bodysystem electronics.

Yeah, actually, that's not true. The entire automotive IC portfolio of TI, NXP, Renesas, etc. say hello. There are tons of automotive standards that apply here. They will not use unqualified ICs in ECUs.

Flash on a board will never be and shouldn't need to be user replaceable. They failed in designing it. They should have known the write endurance and selected something more appropriate.

I work in a regulated industry and we had to write tons of log data almost 24/7 to non-volatile memory. We didn't use flash, we spent the money for MRAM. The MRAM write endurance will outlive the useful life of the device.

 

[chris719]

In a automotive context a wear item is designed to be replaced at nominal intervals. This eMMC chip is ball-grid soldered to the motherboard, inaccessible without disassembling the dash, and not specifically mentioned in the owner’s manual.

Yeah, it's pretty ridiculous to suggest that you should give customers of your car access to embedded low-level storage. Tesla just screwed up, that's all.

 

[Wombat]

Tesla wasn't an experienced car maker. I am not convinced that they have got there, yet.

 

[restorer-john]

In a automotive context a wear item is designed to be replaced at nominal intervals. This eMMC chip is ball-grid soldered to the motherboard, inaccessible without disassembling the dash, and not specifically mentioned in the owner’s manual.

BGA RAM has been soldered to removable/replaceable RAM sticks, be they full size, SODIMM or whatever for decades. Static/Flash RAM has had everything from SATA to mini PCIE, Micro SD and whatever the latest is. All plug and play replaceable. I would consider an M.2 SSD screwed down to be a superior long term connection, particularly in the face of extreme temperature fluctuations and vibration as seen in vehicles, especially as PbFree BGA chips are falling off PCBs the world over, in extreme conditions.

They are a young carmaker. They have a lot to learn and are trying to do it all at once. They will of course make mistakes. Doesn't make them inept, but basically everyone driving these things are beta testers. They will get there and be excellent, I'm sure.

 

[chris719]

BGA RAM has been soldered to removable/replaceable RAM sticks, be they full size, SODIMM or whatever for decades. Static/Flash RAM has had everything from SATA to mini PCIE, Micro SD and whatever the latest is. All plug and play replaceable. I would consider an M.2 SSD screwed down to be a superior long term connection, particularly in the face of extreme temperature fluctuations as seen in vehicles, especially as PbFree BGA chips are falling PCBs off the world over in extreme conditions.

They are a young carmaker. They have a lot to learn and are trying to do it all at once. They will of course make mistakes. Doesn't make them inept, but basically everyone driving these things are beta testers. They will get there and be excellent, I'm sure.

They don't want it to be easily accessible or removable. That's the point. Nevermind the fact that most SoCs in infotainment systems don't exactly have spare PCIe lanes to connect to something that doesn't require high performance.

 

[mansr]

In a hot, filthy, high-vibration environment like a car, you want to avoid connectors as much as possible. High-speed, low-voltage signals as used for these storage devices are especially sensitive. Soldering is the way to go. If something fails, the whole module can be replaced.

 

[chris719]

In a hot, filthy, high-vibration environment like a car, you want to avoid connectors as much as possible. High-speed, low-voltage signals as used for these storage devices are especially sensitive. Soldering is the way to go. If something fails, the whole module can be replaced.

Agree totally. Shame it's on such an expensive module, though.

 

[Wombat]

Replacement - let's say $1350. Ouch.

Early days the quotes were much higher.

https://www.thedrive.com/tech/27989/teslas-screen-saga-shows-why-automotive-grade-matters

 

[restorer-john]

In a hot, filthy, high-vibration environment like a car, you want to avoid connectors as much as possible.

I understand, but consider every single connection to a body system computer is a bespoke connector. Every connection in the engine bay is a plug/socket, male/female connector. Everything under the dash is plug/socket. There are literally many hundreds of such connectors in cars.

The wear items (such as static RAM/flash) are a mere few more connectors, with a low mass, gold plated, low contact force, physically secured connections. The WiFi cards are already leveraged from PCs, what's the difference?

 

[Wombat]

Tesla may have used free out-of-patent Lucas Electrical patents - haha.

 

[chris719]

I understand, but consider every single connection to a body system computer is a bespoke connector. Every connection in the engine bay is a plug/socket, male/female connector. Everything under the dash is plug/socket. There are literally many hundreds of such connectors in cars.

The wear items (such as static RAM/flash) are a mere few more connectors, with a low mass, gold plated, low contact force, physically secured connections. The WiFi cards are already leveraged from PCs, what's the difference?

I see your point, and I do agree it could be done. I just don't think Tesla wants to do it. They probably will keep on using cheap flash in new designs just adding more and adjusting the write strategy so it fails on the 2nd owner.

 

[restorer-john]

I see your point, and I do agree it could be done. I just don't think Tesla wants to do it.

I don't own a Tesla, so I don't know whether it can be operated/driven when there is a major failure in the particular system we are discussing. I would assume (perhaps incorrectly) that the vehicle would be fully driveable and safe?

If that is not the case, it makes those parts considerably more "mission critical" and subject to more redundant backup or at least a grade of component not subject to premature failure, particularly if they are not easily replaceable.

I have to say this. The thing about an M.2 SSD failure is it is sudden and complete in my experience. No warning. No data errors. Fine one day, dead the next. Not like a HDD where you get plenty of warning and time to kick yourself for not replacing it when you had the chance.

 

[chris719]

I don't own a Tesla, so I don't know whether it can be operated/driven when there is a major failure in the particular system we are discussing. I would assume (perhaps incorrectly) that the vehicle would be fully driveable and safe?

If that is not the case, it makes those parts considerably more "mission critical" and subject to more redundant backup or at least a grade of component not subject to premature failure, particularly if they are not easily replaceable.

I have to say this. The thing about an M.2 SSD failure is it is sudden and complete in my experience. No warning. No data errors. Fine one day, dead the next. Not like a HDD where you get plenty of warning and time to kick yourself for not replacing it when you had the chance.

Apparently even things like the defroster stop working when that flash goes bad. Overall a bad software architecture it seems like.

Yeah, when flash that's hidden behind a controller goes bad you usually don't get any indications other than metrics if provided by the controller. The bad block handling and wear leveling is supposed to be transparent.

 

[mansr]

I understand, but consider every single connection to a body system computer is a bespoke connector. Every connection in the engine bay is a plug/socket, male/female connector. Everything under the dash is plug/socket. There are literally many hundreds of such connectors in cars.

Most of the connectors in a car handle slow signals with high voltage/current. That makes all the difference.

The wear items (such as static RAM/flash) are a mere few more connectors, with a low mass, gold plated, low contact force, physically secured connections. The WiFi cards are already leveraged from PCs, what's the difference?

You don't want low contact force in a high-vibration application. The wifi "cards" you speak of are mostly likely modules soldered to the same PCB as the CPU and RAM.