7 ms·
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.
by atmosx 3y ago
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.
- mongol 3y agoYes I remember being surprised that Linux containers were used for that purpose.
- srcreigh 3y agoVery OT, but I concur. I need a DSP for my car audio system. I considered a rpi3 with a DAC attachment. 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!!!
- pid-1 3y agoSearch ebay etc... for Texas Instruments DSP evaluation boards.
- ju-st 3y agoYou could use a ADAU1701 DSP board (cheaper and shittier minidsp) or do it directly on a modern/fast microcontroller, e.g. ESP32. I used an ESP32 to adjust frequency response of a small diy loudspeaker (and added Bluetooth).
- JeffeFawkes 3y agoIf you make your own buildroot image, you can get VERY quick boot times - here's a random vid I found [1] with 3.5 seconds on a pi zero w (which is considerably less powerful than a Pi3. 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. [1]: https://www.youtube.com/watch?v=ZehLyumyMvE https://www.youtube.com/watch?v=ZehLyumyMvE
- kragen 3y agoi feel like maybe 3.5 seconds is not VERY quick compared to 28 milliseconds?
- cinntaile 3y agoThe use case is different so the comparison doesn't really matter.
- yjftsjthsd-h 3y ago28ms is a VM; in hardware you can't get through firmware in 28ms. Apples to oranges.
- kragen 3y agotrue if your firmware is shitty enough but plenty of hardware platforms don't have that problem
- red0point 3y agoIt doesn‘t always have to be a RPi, sometimes there is dedicated hardware for that use case that is also kinda cheap. Check this thing out, it‘s a programmable audio DSP: https://www.thomannmusic.ch/the_t.racks_dsp_4x4_mini.htm https://www.thomannmusic.ch/the_t.racks_dsp_4x4_mini.htm
- deleted 3y ago[deleted]
- SomeoneFromCA 3y agoCan't you just run on bare metal on rpi? Also a resistor, a capacitor and a realay would work to filter out the extra bass.
- jakear 3y agoWild that people have accepted a 5000ms delay between starting their car and seeing behind them. 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.
- chii 3y agoprobably because it started off as a 1000ms delay, which they begrudgingly accepted. Then it started to slow to 1100ms....
- cwalv 3y agoUp until a couple years ago my car didn't even have a camera. We just looked out the window, which is still an option.
- Sharlin 3y agoA large majority of cars in traffic don’t have a back camera. Either because they’re old or because they’re cheap (I don’t think a back camera is usually a standard feature at least where I’m from…)
- kalleboo 3y agoIn the US a backup camera is now required by law
- Someone 3y agoFor new cars, I guess. In the EU, it’s similar. https://ec.europa.eu/info/law/better-regulation/have-your-say/initiatives/12224-Vehicle-safety-technical-rules-test-procedures-for-advanced-safety-features_en 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.
- CalChris 3y agoMy 2015 Model S would lose badly in a quarter mile against a good cyclist if you included cold boot time. Worst bank robbery car ever.
- rfmoz 3y agoWith a custom kernel and without initrd/initramfs is possible to boot around 1 second.
- rascul 3y agoMight be quicker if you put everything you need into an initramfs that's built into the kernel. Then there's no slow storage needed once the kernel is loaded.
- hwd 3y agoThere is an interesting talk from BMW how they did it for their cars: https://youtu.be/_cSTBiwY7HE https://youtu.be/_cSTBiwY7HE.
- ciupicri 3y ago"Linux Kernel Fastboot On the Way", Linux Plumbers Conference 2019, https://www.linuxplumbersconf.org/event/4/contributions/281/attachments/216/617/LPC_2019_kernel_fastboot_on_the_way.pdf https://www.linuxplumbersconf.org/event/4/contributions/281/... / https://www.youtube.com/watch?v=A7N_O8pnyTw https://www.youtube.com/watch?v=A7N_O8pnyTw
- avidphantasm 3y ago3-5 seconds sounds like the latency I see in my 2018 Toyota’s garbage Entune 2.0 system. It’s criminal that things like this are released for general usage.