5 ms·

Computing in automotive is a challenge. In the past, you might have automotive-grade microcontrollers for functions like ABS, which consume less than a Watt ma

Computing in automotive is a challenge. In the past, you might have automotive-grade microcontrollers for functions like ABS, which consume less than a Watt maximum. You paid a little attention to having enough ground vias on the PCB for thermal conductivity, and that was about it to qualify the design for the high end of the temperature range. Degraded lifetime wasn't so much of a concern. These days, you've got ARM processors with a TDP of 15W or more, and keeping the die temperatures below the maximum when the ambient temperature is 85C, well, that starts to get interesting. Especially if you don't want to use a fan, and the processor is stuck somewhere without adequate airflow. And then you've got high-end systems with a TDP in the 150W range. Then you've got to have a good cooling solution to run your application at office environment temperatures, nevermind the full automotive temperature range. And what's going to be the lifetime for these parts running at elevated temperatures, even if you are staying within the maximum temperature limits? Sigh

carlmr 9y ago
Automotive chips under the hood have to be rated up to 125°C environmental temperature. 150°C in some locations.
- ansible 9y ago
  Yep. The junction temperature is rated up to that. What I'm saying is that even so, thermal design is a challenge. And I have concerns about chip lifetime under those sorts of conditions.
  - roymurdock 9y ago
    As more critical functionality in cars comes to be controlled by MCU/CPUs and software over ECUs and mechanical components, I wonder if software obsolescence will have a larger impact than potential chip failure from increased use. It's not hard to imagine a future where Tesla stops developing and pushing updates for cars after 5-10 years, basically forcing an owner to trade up as the hardware in older models becomes incompatible with the latest self-driving algos. It's also not hard to imagine a future where Amazon/Uber/Bigco own and update large fleets of vehicles, maintaining and renting them out much like AWS does compute cycles, taking the burden off the user to maintain their own hardware.
    - Slansitartop 9y ago
      > As more critical functionality in cars comes to be controlled by MCU/CPUs and software over ECUs and mechanical components, I wonder if software obsolescence will have a larger impact than potential chip failure from increased use. I don't really see that. Once the software's out there and works, it'll work even if it isn't updated with the latest feature set. I can't really imagine the government changing self-driving car standards so fast that a non-updated car could not operate safely and would have to be retired. Any broken "cloud server dependence" would probably cause so much weeping and gnashing of teeth that Tesla would be foolish to try it, and again, I doubt the government would allow it for safety reasons.
- falcolas 9y ago
  There's the flip side of that too: they can be "stored" in environments which are occasionally in excess of -40°C, and have to function properly then as well (and be subsequently heated back up to above 100°).
Retric 9y ago
15W chips use ~2% of a HP each, and 150W = 1/5 horsepower worth of parasitic load. So using several high end chips should result in significantly worse fuel efficiency. Are they really necessary or just cheaper in R&D terms?
- simias 9y ago
  Modern cars have tons of advanced features that require a decent amount of computing. I mean just look at the evolution from radio cassette players to modern integrated GPS/media player/bluetooth/etc systems. Also things like automatic parking assist, rear view camera, computer vision algorithms to detect if the driver is falling asleep. It's feature creep all over the place.
  - oblio 9y ago
    > Also things like automatic parking assist, rear view camera, computer vision algorithms to detect if the driver is falling asleep. It's feature creep all over the place. You have a weird definition of "feature creep". Some of those things you listed save money, others save lives. I definitely wouldn't include such things in "feature creep".
    - simias 9y ago
      Sorry, it might not have been the right word. I didn't mean that these features weren't useful, only that in the past decades the past decades the amount of software in cars really exploded from basically 0 to having a bunch of fully featured computers dealing with various subsystems, from fuel injection to radio playback. Software "creeped" everywhere.
- bluGill 9y ago
  Going by your numbers and my best guess, I think the processing of self driving cars needs 1/4 hp. The first few generations will need more than that. (you can get by on less if you are willing to sacrifice safety)
  - 9y ago
sixdimensional 9y ago
It's even worse in avionics. The turn to commercial off the shelf (COTS) parts to cut costs has raised the cost of using specialized ones (or caused people to have to develop custom solutions at great cost due to market gaps). High temperature tested CPUs (above consumer grade) is a good example. IOT causing more and more embedded technology might help change that tide, due to the need for components that can handle extreme and longer term deployments. But, the last so many years of the push to cut costs through COTS has come at a big cost for sustainability.

carlmr 9y ago

Automotive chips under the hood have to be rated up to 125°C environmental temperature. 150°C in some locations.

ansible 9y ago
Yep. The junction temperature is rated up to that. What I'm saying is that even so, thermal design is a challenge. And I have concerns about chip lifetime under those sorts of conditions.
- roymurdock 9y ago
  As more critical functionality in cars comes to be controlled by MCU/CPUs and software over ECUs and mechanical components, I wonder if software obsolescence will have a larger impact than potential chip failure from increased use. It's not hard to imagine a future where Tesla stops developing and pushing updates for cars after 5-10 years, basically forcing an owner to trade up as the hardware in older models becomes incompatible with the latest self-driving algos. It's also not hard to imagine a future where Amazon/Uber/Bigco own and update large fleets of vehicles, maintaining and renting them out much like AWS does compute cycles, taking the burden off the user to maintain their own hardware.
  - Slansitartop 9y ago
    > As more critical functionality in cars comes to be controlled by MCU/CPUs and software over ECUs and mechanical components, I wonder if software obsolescence will have a larger impact than potential chip failure from increased use. I don't really see that. Once the software's out there and works, it'll work even if it isn't updated with the latest feature set. I can't really imagine the government changing self-driving car standards so fast that a non-updated car could not operate safely and would have to be retired. Any broken "cloud server dependence" would probably cause so much weeping and gnashing of teeth that Tesla would be foolish to try it, and again, I doubt the government would allow it for safety reasons.
falcolas 9y ago
There's the flip side of that too: they can be "stored" in environments which are occasionally in excess of -40°C, and have to function properly then as well (and be subsequently heated back up to above 100°).

Retric 9y ago

15W chips use ~2% of a HP each, and 150W = 1/5 horsepower worth of parasitic load. So using several high end chips should result in significantly worse fuel efficiency. Are they really necessary or just cheaper in R&D terms?

simias 9y ago
Modern cars have tons of advanced features that require a decent amount of computing. I mean just look at the evolution from radio cassette players to modern integrated GPS/media player/bluetooth/etc systems. Also things like automatic parking assist, rear view camera, computer vision algorithms to detect if the driver is falling asleep. It's feature creep all over the place.
- oblio 9y ago
  > Also things like automatic parking assist, rear view camera, computer vision algorithms to detect if the driver is falling asleep. It's feature creep all over the place. You have a weird definition of "feature creep". Some of those things you listed save money, others save lives. I definitely wouldn't include such things in "feature creep".
  - simias 9y ago
    Sorry, it might not have been the right word. I didn't mean that these features weren't useful, only that in the past decades the past decades the amount of software in cars really exploded from basically 0 to having a bunch of fully featured computers dealing with various subsystems, from fuel injection to radio playback. Software "creeped" everywhere.
bluGill 9y ago
Going by your numbers and my best guess, I think the processing of self driving cars needs 1/4 hp. The first few generations will need more than that. (you can get by on less if you are willing to sacrifice safety)
- 9y ago

sixdimensional 9y ago

It's even worse in avionics. The turn to commercial off the shelf (COTS) parts to cut costs has raised the cost of using specialized ones (or caused people to have to develop custom solutions at great cost due to market gaps). High temperature tested CPUs (above consumer grade) is a good example. IOT causing more and more embedded technology might help change that tide, due to the need for components that can handle extreme and longer term deployments. But, the last so many years of the push to cut costs through COTS has come at a big cost for sustainability.