gerits
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Re: In-car entertainment system

Sat Oct 15, 2011 12:00 pm

Just recently I came up with a great idea and I've also started the project.

I'm trying to create an in-car entertainment system. The raspi would be build in somewhere behind the dashboard en will be controlled via an android phone over bluetooth or wifi.

I've already started the programming work. I'm creating a mplayer frontend for playing the music, and will add some features to transfer music over bluetooth/wifi.

The only problem I have is that it takes about 20-30 seconds to boot on a clean debian install, this would have to drop below 10 seconds before it becomes an usable system (suggestions are welcome).

I hope I've enough time to finish the project so I finally have some music in my car without screwing up the looks of it.

PiOfCube
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Re: In-car entertainment system

Sat Oct 15, 2011 12:56 pm

You probably already done this but if you take off unnecessary items out of the start-up list (runtime level) then that should improve the speed somewhat. I'm not sure what's being loaded with the install you are using but I don't think that CUPs and a large number of the other software would be needed.

Again, if you haven't already, use sysv-rc-conf to have a look on your development unit. PCMCIA would probably be a good contender to stop running as well as the networking stuff as I assume it wouldn't have internet access... Unless that's an option you might want if you are thinking of tethering it to a mobile phone?

Also, take a look at any cron jobs and startup scripts to see if you can remove un-needed stuff there.
- 1BillionHex aka PiOfCube: 68719476738 -

gerits
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Re: In-car entertainment system

Sat Oct 15, 2011 2:01 pm

I was thinking about doing a clean install once the raspi arrives and then see how fast it runs. But even a stripped linux on a 700mhz processor would require at least 20 seconds.

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abishur
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Re: In-car entertainment system

Sat Oct 15, 2011 2:04 pm

If you set it up to start with the car, then 30 seconds isn't really that unacceptable. I had a co-worker who used a traditional in-dash computer and would have been quiet happy with 30 seconds to boot. One thing you can do is have it receive power even with the car off. A watt or two of power won't kill a car battery if you leave it plugged in overnight, but if you really wanted to go the fancy route you could add a second car battery solely for powering the r-pi. That's what my co-worker did, but he had a bigger power requirement to worry about.
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gerits
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Re: In-car entertainment system

Sat Oct 15, 2011 2:46 pm

But 30 seconds is still slower then a normal car system. But the measured 30seconds of the raspi was with GUI, so I expect about 20 seconds to have a running system.

jewesque
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Re: In-car entertainment system

Tue Oct 18, 2011 5:53 pm

Again, that all depends on what you're looking to boot. If the R-Pi doesn't need to boot a GUI you could shave some time there too. I think the best solution here is to have a battery pack that the R-Pi runs directly off of, and then you use the switched power that would normally power the comp and run it be the charge source for the battery. This way you get two major benefits. First, you can use the device for an extended period with the car effectively off. Second, it acts as a backup/power filter. If your car briefly loses power (typical when stalling/restarting the car with a manual), the comp doesn't get tripped, and if you experience power fluctuations typical from the alt, you can regulate that better.

That's sort of what I'm planning to do, but I haven't quite put it all together how it'll work yet. I'll likely have to do a lot of research for it. Moreover, I want mine to play host to a screen as well, which gets a lot more difficult, especially as regards power concerns.

Nick Scott
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Re: In-car entertainment system

Tue Oct 18, 2011 6:52 pm

Another option would be looking at one of those car audio super capacitors. Connect it to a decent power source, when the car turns on it would charge it up, (the raspberry pi would be started at this time), and when the car starts, it won't turn off (more of an issue in Diesel's, where they have to glow before starting). That way 20 - 30 seconds becomes almost irrelevant, by the time the vehicle is started, itl be halfway through boot.

hippy
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Re: In-car entertainment system

Tue Oct 18, 2011 7:00 pm

Most of us use vehicles at fairly predictable times so it should be possible to have a supervisory micro which powers up just before we are likely to use them and can shut down based on ignition turned off for a certain length of time at particular times. That minimises power consumption when not needed and ready to go when we want. Cold start boot times can likely be tolerated for those rarer situations which don't fit normal usage patterns.

I'd also recommend some sort of secondary battery, just to carry it through any brownouts when cranking and so on.

Nick Scott
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Re: In-car entertainment system

Tue Oct 18, 2011 7:13 pm

Other thought for secondary battery (trying to think of something that's easy to install as well, and is easy to find a spot to hide it), would be an alarm battery. Could even run the whole system off that (and charge it when the engine is running) so that you don't risk draining your main battery).

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Re: In-car entertainment system

Sun Dec 25, 2011 4:25 pm

A stand by battery to keep Raspberry Pi alive when "cranking". Simple answer to 30 seconds is: couple your device to remote unlock system. This way you gained minimum of 10 seconds. I would gain full 30 seconds!

However, if you are able to improve on boot time, it will be an bonus to above suggestion.

willj12
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Re: In-car entertainment system

Sun Dec 25, 2011 9:21 pm

You would want to use something like the M2-ATX (http://linitx.com/product/10917), this would take the voltage from the battery and regulate it giving you a 12v and 5v rail which could be used to power the Raspberry Pi. It also says powered during cranking, this is what I use in my current Car-PC.

If the power switch connector could be converted from a normal motherboard to the Raspberry Pi then it would be perfect!

mobeyduck
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Re: In-car entertainment system

Sun Dec 25, 2011 9:53 pm

that thing is 160W dont you think thats way over the top?

You could use some thing like this http://www.tigerdirect.com/app.....CatId=5248

It already has its own powersuply from the car and changing 12v to 5v shoudnt be to hard. bit strange resolution but i bet you can get it working 1440H x 234W.

Good side is you can add a rear-view camera it can auto-switch to it :)

Wooloomooloo
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Re: In-car entertainment system

Sun Dec 25, 2011 10:03 pm

mobeyduck said:


that thing is 160W dont you think thats way over the top?


Then again, this thing seems surprisingly well matched the RPi (at least the 5V rail): http://www.mini-box.com/picoPSU-90-XLP

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Re: In-car entertainment system

Sun Dec 25, 2011 11:26 pm

On power supply, there is an excellent post by thunder_x in this forum. I have requested some more link from this person. Almost all power supply made for PC mother board would be an overkill. A good quality car charger cable is what you need. When Raspi drop through my letter box, I am going to assemble a power circuit using a three terminal regulator etc + small cheap 6 volt re-chargeable battery with standby charging circuit + 1 to 2 DC blocking diodes and Heat sink. I can get all this from Maplin!

I have done this sort of thing many time before. It will work from 28 volt as well.

Blars
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Re: In-car entertainment system

Mon Dec 26, 2011 1:20 am

TI makes some switcher chips that are designed to output 5v from a car battery even when cranking, they switch from buck to boost mode as needed.

squoblat
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Re: In-car entertainment system

Mon Dec 26, 2011 11:41 am

Could you not run android on the Pi itself? This is what I intend on doing, provided I can use my usb GPS dongle and touch screen effectively. I can't imagine booting into an android ROM will take more than 15 seconds.

grenadejumper
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Re: In-car entertainment system

Fri Dec 30, 2011 1:36 pm

Check out this guy, working on fast boot for fedora linux on raspberry pi: 0.3 Raspberry Pi Startup  Doesn't look too bad

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Gert van Loo
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Re: In-car entertainment system

Wed Jan 25, 2012 8:22 pm

Looking For Developers said:


....When Raspi drop through my letter box, I am going to assemble a power circuit using a three terminal regulator etc...


I would not do it that way. Your three terminal regulator needs to burn away  12V-5V=7V*1A =  7W.

I have a three terminal regulator on my Gertboard and I fed it 7.5Volts. It got very, very hot. I added a heat sink but that helped only a little bit. I had not realized how much heat 2.5W is. Definitely go for a switch mode regulator. They are more difficult to build but they don't get so hot.

turbocrow
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Re: In-car entertainment system

Wed Jan 25, 2012 9:29 pm

I will be keeping my eye on this thread has I was planning to do this the day the Raspberry was announced lol

redm4lc
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Re: In-car entertainment system

Tue Feb 28, 2012 1:45 pm

Funnily enough, I've just been pondering this same thing. I've got a MK5 Golf at the minute and was looking at buying an RNS 510 soon – hitting my wallet pretty hard at around £500+

I'm wondering what components I'd need to make my own one? Obviously it needs further research for sourcing components and understanding how my system currently works. But at the bare minimum:


Screen (most costly, obviously. Has to fit..)
Powered by Pi
Connector for speakers
The right OS

Then obviously some interface device. Has anyone thought this through much?
EDIT: Oops, only just noticed this thread has a *first* page

Annesville
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Re: In-car entertainment system

Wed May 23, 2012 12:56 pm

Regarding the screen: mp3car has a complete display kit the MkV. Otherwise you need a Lilliput screen, and facia kit from American International (or if you aren't fussy, Metra or Scosche) and some handywork.

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