There was an article about a Linux embedded system handling a car back-camera that had to boot within 3-5 seconds or something along those lines.
I tried the raspbian OS with some moderate overclocking and removing unneeded startup processes. Couldn’t get it under 25 seconds for boot. Kind of a deal breaker (remote start unit could help, but…)
Apparently somebody can start the rpi3 in <3 seconds. I’ll believe it when I try their image myself. Their setup disables USB and networking (maybe audio too who knows) which is a giant pain for configuring my system.
Maybe I’ll try again with an RPi 4 and usb3 nvme. or maybe I’ll just pay hundreds of dollars for a dedicated DSP unit.
In case anyone cares, my main use case is parametric EQ for phon adjusted low bass frequencies. 90dB 20Hz sounds as loud as 70dB 50Hz (give or take) and subwoofers are generally quieter at lower frequencies. Hence, audio processing unit to cut as you go higher than your lowest decently loud frequency.
The lowest cost option for this is about $230USD plus some electrical components (miniDSP 2x4HD). I figure the rpi would cost around $100 including the DAC unit, open source audio software, just need some power source to link the battery to the rpi power cord.
Edit: I don’t want to spam thanks comments for helpful replies, so I’ll just say it here (possibly in advance): thanks!!!
I've worked with similarly underpowered boards (licheepi zero, only has 64mb ram and uses the cpu from a dashcam!) and those will still boot and start an SDL app in under five seconds.
If you can identify the bare minimum that you need for your EQ solution, you can probably get similar boot times.
Check this thing out, it‘s a programmable audio DSP:
I suppose I'm more sensitive to downtime than most - I recently (unsuccessfully) tried to add a ton of capacitance into my head unit's power supply and acc-signal lines to keep it from turning off for a few seconds when starting the engine.
Dismissing it as "design with poor usability" is very facile. It's trade-offs between different goals, all the way down.
Those pillars that hold the roof up are safer if they're sturdy, but sturdy means wider and that obstructs the driver's field of vision a bit, and weighs more. "strong and slender" is possible, but it costs more. It all inter-relates.
(strong, narrow, cheap), pick any 2.
There does come a point where you start to appreciate what Polestar is doing on one of next years models (the Polestar 4): give up on the idea and change direction; no rear window at all, just a camera.
And I'm not only thinking about damaged camera. Humidity, weather etc. often makes these cameras completely useless.
You'd have to have wipers for your camera-lens and probably heating or something as well to even approach the utility of a window - short term.
Because none of that is ever going to fail, and it isn't cheap either.
It is IMHO a bold move, which will attract fans and haters. Neither of us know for sure how it will play out; if the potential issues outweigh the rest. The implementation details clearly matter. In a couple of years we will see if it's a genius innovation, a terrible misstep or somewhere in-between. Until the vehicle ships and is on the road for some time in some volume, we won't know for sure.
After all, on a high-end vehicle a back-camera that hasn't sorted this is just a gimmick.
Maybe they have, all my experiences indicate otherwise though I don't have much experience with new expensive cars.
Reminds me of the 18 wheeler at the traffic light. He got red while waiting for his left turn and decided to back up instead of "going for it" once oncoming traffic had seized.
The minivan behind him got crushed like it was made of sticks. Luckily he heard the noise after a while and stopped backing up. Not a pretty sight. I had the side view so I was like "WTF is he doing?" when he started backing up. Well he couldn't the minivan who had snuck up behind him.
Lesson: when behind a truck make sure you can see the drivers face through his mirrors. Then you have a chance that he is going to see you. If you can't see his face, assume that he can't see you. Move away.
You don't see lots of truck parking in parallel unassisted on streets with pedestrians and cyclists, but I do this all the time.
https://en.wiktionary.org/wiki/Chesterton%27s_fence
It's for safety in case of roll-over and for better aerodynamics due to increased emissions standards and in the case of EVs, increasing the range.
Disclaimer: Not a joke. I've never owned a car.
Convenience :-)
Also, if you live in a sparsely populated area, public transport with good coverage often isn't really economically (or ecologically) feasible, even in countries that have good public transport in cities. A bicycle might be an option if distances aren't too great but relying on it exclusively probably takes more than an average person is willing to take on. Weather conditions could be poor, you might regularly need to transport groceries for an entire family, etc. All of that is entirely doable within a few miles in a bikeable city but it's potentially a lot less so if distances are greater.
I've never owned a car, I bicycle some thousands of kilometres per year (probably more than I drive most years), and I wish people didn't automatically consider owning a car a necessity even when it actually isn't. But I can definitely see reasons for owning one.
In the EU, it’s similar. https://ec.europa.eu/info/law/better-regulation/have-your-sa...:
All new vehicles sold from May 2022 must be fitted with advanced safety features, including:
- monitors that detect when a driver has become drowsy or distracted
- emergency stop signal to help prevent rear-end collisions
- rear-view camera or parking sensors
- alcohol interlock system to prevent drunk driving.
These systems will help reduce serious accidents on Europe’s roads.
Wait, what? _All_ new vehicles need to have this? Or do they just need to be constructed such that one can be installed easily?
Also, see:
https://road-safety.transport.ec.europa.eu/statistics-and-an...
Edit:
The actual text:
> Article 6 of Regulation (EU) 2019/2144 of the European Parliament and of the Council requires motor vehicles of categories M and N to be equipped with certain advanced vehicle systems, including driver drowsiness and attention warning systems. It lays down in its Annex II basic requirements for the type-approval of motor vehicles with regard to the driver drowsiness and attention warning systems.
Even the Mini Cooper is huge now.
The delay that I notice the most is the time it takes to connect to my phone via Bluetooth (usually so I can play music from it). I’m often already pulling out of my parking space before it connects.
I can change gears in well under a second when moving. My car requires the clutch to be depressed when the car starts, meaning that I can actually ahve the car started in reverse in under a second. Waiting another 4 seconds is crazy.
And if you’re reversing within 3 seconds of turning your engine on then you’re either driving recklessly or on an open and safe space where you don’t even need your cameras.
To be clear, I’m not suggesting that a 4 second boot time for an embedded device is great. But I do think your claim that waiting 4 seconds “is crazy” is rather hyperbolic.
If I've parked my car, I have to have my foot on the clutch to turn it back on agian. My foot is already on the clutch, and I can very easily (and often do) put my car in gear _immediately_.
> then you’re either driving recklessly or on an open and safe space where you don’t even need your cameras.
Or I've looked in my mirror and put my seatbelt on before I turned the engine on. This is the equivalent of "you're holding it wrong".
My point being, 5 seconds might sound like an eternity on paper but I’d wager it’s not nearly as impactful once you start factoring real world scenarios.
Personally, I never look at my camera. I just listen to the beeps and watch my blind spot. Not because it’s safer not because of any delay in the camera coming on, but simply out of habit. So I’ve never noticed a delay in the camera coming on. Maybe there isn’t even a delay in my particular car — but if there was, I wouldn’t know.
I think it works better now than before, but it's hard to be sure because I neglected to measure the downtime before/after the modifications. Essentially I had a cap/diode to keep the acc line high during startup for the head unit, but it would still cut off due to the power supply voltage dropping to ~10-11V on the engine turning over (4.8L V8). So then I added a cap/diode to the power supply line, and it works "better...ish...maybe..." now: there are some times when it will stay on across startup, but not always. Perhaps with a larger cap on the PS line (I'm using ~2500uF), but it seemed to be discharging much faster than I'd expect, as if the diode wasn't doing it's thing and the line was effectively just at the system's general "+12V". I wondered if there was perhaps some way the power was escaping the diode/cap isolation and making it back into the main system, but I didn't have a good way to test or fix that (I previously diagnosed a similar issue to a bad diode, but this one seemed to measure fine).
And besides all that, the amp is on a separate line in the way back of the car that I didn't bother to tear into because the head unit turns off in the critical stage anyways. So the head unit does stay on for a couple seconds after I turn if off completely, but since the amp is off it doesn't matter.
So delayed startups aren't some new issue.
If you believe your idea is true, can you tell me what I can expect to see if I don't do this? IE, I've never done this and I have cars that last 10+ years without any engine trouble.
Also my usual sequence is "start the engine, set up on phone (music, GPS), leave", so it would've booted before I need it.