4 ms·
When this first came out, I recall reading that the reason the watchdog timer was reset from the timer interrupt was because as they added more software and ove
by pjdesno 4y ago
When this first came out, I recall reading that the reason the watchdog timer was reset from the timer interrupt was because as they added more software and overloaded the CPU, things got slower and the timer started triggering during normal operation. This caused the engine to hiccup if the vehicle was moving, or stall if you were at a stop. (IIRC reboot takes ~125ms, so no spark during this time)
The watchdog is the last-ditch failsafe, in a safety-critical system, and they basically disabled it because it was inconvenient. In some businesses (aviation?) you could probably be convicted of something for doing that, whether or not it ever hurt anyone.
- elfchief 4y agoOne thing that I found amusing/interesting/horrifying back when I read about this originally is that you can measure the computer reboot time in feet. IIRC, in the problem vehicles, the reboot time was something like 150 feet @ 60mph.
- hatsunearu 4y agoWell, good thing is during that reboot time your brakes will likely work to its full potential, you'll have engine braking, your clutch will work, your transmission might work if you have a separate TCM, your steering will work with power steering. You will just lose power, as though you let off the throttle fully, during this time. In fact your car turns off fueling when you let off the throttle fully to conserve fuel. I think the only danger is that if you were going full tilt on a sports car, and the throttle failed close, you will get lift off oversteer probably.
- winrid 4y ago> "your transmission might work if you have a separate TCM" This is why well engineered vehicles have a separate computer for everything and not just one little chip.
- civilized 4y agoWhat's infuriating is, think about how much of that software was probably worthless bloat for features no one needs. As many as 89 people may have died so Toyota could claim Bluetooth and MP3s in their latest models.
- oofbey 4y agoI wonder how much the software engineers at Tesla & similar think about this stuff. I bet not much.
- shepherdjerred 4y agoWhy do you say that? Has Tesla has a similar set of incidents (unrelated to its self driving features)
- carlmr 4y agoYou're comparing apples and oranges. Compare how many cars Toyota vs Tesla puts on the road. Then divide the number of cases here 89 by that multiplier. You will find that even if Tesla had similar issues, they would in many cases just not be detected.
- bhk 4y agoNot so, according to NASA and NHTSA. More mundane, physical masters were at fault.
- PaulHoule 4y agoI'd assume the entertainment is decoupled from any engine control, drivetrain control or drive-by-wire features.
- chomp 4y agoYou're correct, this is the ETCS, which is a piece of the electronics in a Toyota. It's responsible for feeding speed, sensor, and drive control inputs in, and figuring out EFI, throttle, timing and stuff like that.