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I'm not an embedded developer, so I don't have much value to add re: architecture; however, this caught my eye: > The microprocessor has to run for 10+ years i

I'm not an embedded developer, so I don't have much value to add re: architecture; however, this caught my eye: > The microprocessor has to run for 10+ years in a wide range of temperatures and be dirt cheap, so you end up with specs like 180 MHz, 4 MB of flash and 128 KB of RAM. If I'm paying tens of thousands of dollars for a car, how come they're using the cheapest possible components? If tinkerers can ship the Raspberry Pi for $30 per board, inc. a 900Mhz quad-core chip and 1GB RAM, you'd think GM could get components at least that modern for an insignificant cost relative to the car they are controlling.

rtpg 11y ago
This is because the parts are orders of magnitude more expensive when being put in harsh environments These "really slow" parts are actually tested and built for much more extreme conditions. For microchips that go into satelites, you even have hand-checked chips that go through a very long (and costly compared to something like a Pi) testing process. Multiply this by all the eletrical components, and you got yourself a lot of things to check. Put your Raspberry Pi next to a car motor, and it's pretty likely(1) a part will fail in the heat and grime conditions. (1) actually, I'm not sure about the likelihood, but there's no assurance that it will be fine
- TeMPOraL 11y ago
  > Put your Raspberry Pi next to a car motor, and it's pretty likely() a part will fail in the heat and grime conditions. Depending on how hot your motor goes, there's a good chance that unshielded Pi will simply de-solder itself into pieces.
- danjayh 11y ago
  Fun harsh environment: I reviewed software a few weeks ago that ran on one of our boards while it was irradiated by a neutron source (I work in aerospace). Radiation has interesting effects on electronics :).
TeMPOraL 11y ago
$30 Raspberry Pi (2) reboots itself when exposed to strong light. The RPi line is also totally unreliable, it tends to bug up and/or crash after running for too long. The car components are made to different spec than consumer electronics (for starters, there are several types of component, depending on what "range of temperatures" you need to operate them in; e.g. the stuff that goes into the traffic lights in northern parts of Europe is not something you buy off Farnell for your hobby project), and they also need to be reliable and tested. Add, of course, the usual graft and overhead. Another thing is that a engine controller doesn't need a near-GHz quad-core chip and shit ton of RAM. It's not meant to stream HD videos or run Python, it has to run a bunch of feedback loops fast enough. Less powerful chips tend to be cheaper and more reliable.
- monkbroc 11y ago
  All good points. The CPU, Flash and RAM share the silicon die with lots of specialized peripherals like CAN controllers and hardware timer units. There's a lot more on the chip than just a CPU. Also, cost is king in automotive...
mikestew 11y ago
If I'm paying tens of thousands of dollars for a car, how come they're using the cheapest possible components? Save a dollar on the part, and you make a million cars, how much does that add up to? Or conversely, why spend more than you have to if the quoted specs do the job? What the hell am I going to do with four cores if I follow the well-written description above? And I'd give your Raspberry Pi a lifespan of about a month if you were to strap it to the firewall of your car while you drive it. Less if you actually powered it up.
- bkero 11y ago
  You'd do it because the million dollars in parts is peanuts compared to the combined salaries of the engineers who are paid to have the specialized knowledge to do this, and the time it to bring up a new application/car. I know that a million dollars is lowball, but this same principle can be applied to other components and scaled up (to a point). Potting electronics in epoxy isn't terrifically difficult, and would greatly increase the durability. I'm willing to bet that a potted Beaglebone Black (for its real-time subsystem) would do just fine in my engine bay for a very long time. The hard part would be getting a single large-pin-count plug coming out of it to handle all the inputs. This point is actually kind of moot because for a long time the ECUs of cars were located in the passenger cabin with wires fed in through a grommet in the firewall. I'd wager that the cost of replacing this system with some standard real-time platform is so monumental, it won't ever be done. Good luck getting the automotive equivalent of BSPs (board-support packages) running on any system other than this. Where this gets interesting is when the people who actually know this system die start retiring/exiting the market. There will be a pretty strong incentive to 1) keep reusing the same system with no new development, 2) accept the lead time in training students/etc, or 3) start paying crazy salaries for people to go out of their way to learn it.
  - gherkin0 11y ago
    Cars are life-critical systems. If GM half-assed it by putting... > a potted Beaglebone Black (for its real-time subsystem) ...into an actual production car, what happens when the thing breaks down and kills someone? Death, recalls, lawsuits, and massive brand damage. > This point is actually kind of moot because for a long time the ECUs of cars were located in the passenger cabin with wires fed in through a grommet in the firewall. Even in the passenger compartment, cars aren't exactly friendly environments for electronics. They have large temperature swings (from a controlled climate to very hot in summer or very cold in winter). So putting it in the passenger compartment doesn't necessarily moot concerns over withstanding extreme environments.
esaym 11y ago
You'd be surprised at how much "good" software can accomplish. Just think of an 80mhz embedded cpu. You have 80,000,000 calculations per second right there in your hand. In a side project I was involved in. We were using 60mhz chips to modulate data at 1khz. I kept worrying about running out of cpu cycles, I mean after all, I was doing a few thousand things per second. But in reality, I still had a ton of head room to go :)
acveilleux 11y ago
There's a few things at play here. Economy of scales is huge of course. A lot of the parts are actually shared between many different cars at different price points. There can be on the order of 50+ micro-controller in that car. Do you want to pay 10$ extra for each of them just because they have cooler specs? The various parts are designed at various times so that car might have controllers for the anti-lock braking system that were designed 5 years ago. Hard real-time applications (brakes, ECU, etc.) don't magically need more gigahertz, that engine with direct injection only needs to calculate fuel volume maybe 20000 times per seconds (once per cylinder per 2 rpm) and that would probably be a ridiculous upper bound. In-car navigation and entertainment packages are completely separate from the hardware actually controlling the car.

rtpg 11y ago

This is because the parts are orders of magnitude more expensive when being put in harsh environments These "really slow" parts are actually tested and built for much more extreme conditions. For microchips that go into satelites, you even have hand-checked chips that go through a very long (and costly compared to something like a Pi) testing process. Multiply this by all the eletrical components, and you got yourself a lot of things to check. Put your Raspberry Pi next to a car motor, and it's pretty likely(1) a part will fail in the heat and grime conditions. (1) actually, I'm not sure about the likelihood, but there's no assurance that it will be fine

TeMPOraL 11y ago
> Put your Raspberry Pi next to a car motor, and it's pretty likely() a part will fail in the heat and grime conditions. Depending on how hot your motor goes, there's a good chance that unshielded Pi will simply de-solder itself into pieces.
danjayh 11y ago
Fun harsh environment: I reviewed software a few weeks ago that ran on one of our boards while it was irradiated by a neutron source (I work in aerospace). Radiation has interesting effects on electronics :).

TeMPOraL 11y ago

$30 Raspberry Pi (2) reboots itself when exposed to strong light. The RPi line is also totally unreliable, it tends to bug up and/or crash after running for too long. The car components are made to different spec than consumer electronics (for starters, there are several types of component, depending on what "range of temperatures" you need to operate them in; e.g. the stuff that goes into the traffic lights in northern parts of Europe is not something you buy off Farnell for your hobby project), and they also need to be reliable and tested. Add, of course, the usual graft and overhead. Another thing is that a engine controller doesn't need a near-GHz quad-core chip and shit ton of RAM. It's not meant to stream HD videos or run Python, it has to run a bunch of feedback loops fast enough. Less powerful chips tend to be cheaper and more reliable.

monkbroc 11y ago
All good points. The CPU, Flash and RAM share the silicon die with lots of specialized peripherals like CAN controllers and hardware timer units. There's a lot more on the chip than just a CPU. Also, cost is king in automotive...

mikestew 11y ago

If I'm paying tens of thousands of dollars for a car, how come they're using the cheapest possible components? Save a dollar on the part, and you make a million cars, how much does that add up to? Or conversely, why spend more than you have to if the quoted specs do the job? What the hell am I going to do with four cores if I follow the well-written description above? And I'd give your Raspberry Pi a lifespan of about a month if you were to strap it to the firewall of your car while you drive it. Less if you actually powered it up.

bkero 11y ago
You'd do it because the million dollars in parts is peanuts compared to the combined salaries of the engineers who are paid to have the specialized knowledge to do this, and the time it to bring up a new application/car. I know that a million dollars is lowball, but this same principle can be applied to other components and scaled up (to a point). Potting electronics in epoxy isn't terrifically difficult, and would greatly increase the durability. I'm willing to bet that a potted Beaglebone Black (for its real-time subsystem) would do just fine in my engine bay for a very long time. The hard part would be getting a single large-pin-count plug coming out of it to handle all the inputs. This point is actually kind of moot because for a long time the ECUs of cars were located in the passenger cabin with wires fed in through a grommet in the firewall. I'd wager that the cost of replacing this system with some standard real-time platform is so monumental, it won't ever be done. Good luck getting the automotive equivalent of BSPs (board-support packages) running on any system other than this. Where this gets interesting is when the people who actually know this system die start retiring/exiting the market. There will be a pretty strong incentive to 1) keep reusing the same system with no new development, 2) accept the lead time in training students/etc, or 3) start paying crazy salaries for people to go out of their way to learn it.
- gherkin0 11y ago
  Cars are life-critical systems. If GM half-assed it by putting... > a potted Beaglebone Black (for its real-time subsystem) ...into an actual production car, what happens when the thing breaks down and kills someone? Death, recalls, lawsuits, and massive brand damage. > This point is actually kind of moot because for a long time the ECUs of cars were located in the passenger cabin with wires fed in through a grommet in the firewall. Even in the passenger compartment, cars aren't exactly friendly environments for electronics. They have large temperature swings (from a controlled climate to very hot in summer or very cold in winter). So putting it in the passenger compartment doesn't necessarily moot concerns over withstanding extreme environments.

esaym 11y ago

You'd be surprised at how much "good" software can accomplish. Just think of an 80mhz embedded cpu. You have 80,000,000 calculations per second right there in your hand. In a side project I was involved in. We were using 60mhz chips to modulate data at 1khz. I kept worrying about running out of cpu cycles, I mean after all, I was doing a few thousand things per second. But in reality, I still had a ton of head room to go :)

acveilleux 11y ago

There's a few things at play here. Economy of scales is huge of course. A lot of the parts are actually shared between many different cars at different price points. There can be on the order of 50+ micro-controller in that car. Do you want to pay 10$ extra for each of them just because they have cooler specs? The various parts are designed at various times so that car might have controllers for the anti-lock braking system that were designed 5 years ago. Hard real-time applications (brakes, ECU, etc.) don't magically need more gigahertz, that engine with direct injection only needs to calculate fuel volume maybe 20000 times per seconds (once per cylinder per 2 rpm) and that would probably be a ridiculous upper bound. In-car navigation and entertainment packages are completely separate from the hardware actually controlling the car.