Car audio project

[earthian]

Hello,

So I have started, finished and testing a bit my car media centre project. Here is what I have:

Hardware:
- Raspberry Pi with Raspbian image, hostapd, mpd and vast collection of my oggs, mp3 and flacs
- USB WiFi mini Dongle (RT5730 chipset)
- 12V-5V/5A DC-DC buck converter
- 64 GB Sandisk Extreme SDCard
- Pioneer KEH6600 cassette player
- Audio connector to the Pioneer AUX input

Setup:
I have the 12V-5V converter connected to the Pioneer ISO power cable which has 12V input from the car related to ignition. So when the car is off the power is off. I did connect it to the 12V "always-on" too and it worked, however I am worried that my RPi could drain the car battery too much and I need a lot of power to start the 4L V8 engine.

The control is via MPD client on my phone (Nokia N9) or any other phone via WiFi connection

Here are my questions and problems observed:

1. The WiFi AP disappears after some time when the usage is low (eg. I do not change many tracks). Is there any power management in the standard Raspian image related to USB devices? Only the reboot of the RPi helps to see the AP again. It looks like the USB Dongle is powered down... I did once see it in my laptop but not my phone, so something is rather strange here!

2. The RPi does not always start with the ignition (music does not play and the WiFi AP does not appear) when starting the car... what could be the cause? I suspect power issues, however my power converter is supposed to be 5V 5A if the input is at least 2V higher.. however I do not have much experience with that and the power might not be "clean" enough? What are your thoughts about this?

3. Another issue with the ignition startup is that the power is cut during the engine turning so what happens is the 12V power begins to flow into the RPi and then it is cut when the engine is being turned by the starter motor and then when the engine is on the 12V is restored. This might be a complete power cut or maybe a substantial voltage decrease. Do you know how this works exactly and if it is a danger which I should think about and use a battery?

4. What if I connected my RPi to continous 12V power supply wire from the battery instead? Would that drain my battery? I leave my car off sometimes for a week or two and I am afraid that It would not start in that case.

I look forward to answers, ideas and comments.

- Andy

P.S. The car is TVR Chimaera 4.0L

[Badger101]

Hi,
My setup:
-RPi with openelec.
-WRT54G
-MFD2 Car stereo

I also have a RPi in my car, but I have done it differently.

I have a WRT54G as a wired router (Because of the USB issues), this 'may' be why you are losing wifi.
http://www.raspberrypi.org/phpBB3/viewt ... 28&t=12097

I use a PIC (Which is on all the time), programmed to control the powering of the systems (RPi, Router, Sub).
Both the PIC and the RPi are powered by these:

Code: Select all

http://uk.rs-online.com/web/p/buck-converters/6201029/?searchTerm=pt78ht205h&relevancy-data=636F3D3226696E3D4931384E4B6E6F776E41734D504E266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E5C772B2426706F3D313326736E3D592673743D4D414E5F504152545F4E554D424552267573743D707437386874323035682677633D424F544826

The PIC 'senses' the ignition (Taken from the fuse box), and waits 5 seconds before turning everything on (via relays). Hopefully this is enough time for you to start the car. It also waits 5 minuites after the ignition has been turned off before shutting down the RPi:
http://www.raspberrypi.org/phpBB3/viewt ... 29&t=14255
And then turning off the power.
This might avoid your inconsistent powering up.

Personally I wouldn't leave it on all the time.

Hope this helps.

[uncrocks]

Could you go into more detail about your setup with the PIC, I'm trying to do essentially the same thing you are, but I'm not very familiar with microcircuitry.

[Pi_Master_Wannabe]

Hi,
I was wondering how you're getting on with your project.
I have 2 Pis - one is a XBMC media centre running wirelessly on the master bedroom HDTV and the other is a webcam server project.

I am planning to install one one my car and run xbmc or openelec to have a media centre instead of upgrading the cruddy car stereo, with the potential to add headrest monitors at some point.

Initially i will be running the pi headless and I will be using a remote app on a smart phone to control the software (output being via the 3.5mm jack into an AUX port on the standard stereo).

I am interested in how you got the wifi dongle operating. I am thinking about using an old dlink router mounted under the dash somewhere (as it runs on 12v) but if I can use a dongle to connect the pi and controlling smart phone that would be great.

Dd you use a dongle like this?:
http://item.mobileweb.ebay.co.uk/viewit ... cmd=VIDESC

Also am interested if you sorted out the power. I am planning to use a Belkin USB 5.0v/1.0a cigarette lighter adapter to power the pi. Have you worked out anything more reliable?

Thanks.

[loganthegun]

Hello!
I am also planning a carputer project in an old Cadillac...So far i have;
- Raspberry Pi B+ W/openelec XBMC for an OS
- IR unit and remote

Now the next step from what i have read is a power supply and a way to display. I am thinking about running it to my touchscreen head unit but i am unsure of the compatibility. It has a usb and a A/V i may use the DAC+. But if it decideds not to play nice maybe a custom box with a 7" touch screen? And then the power. woof. so many diffrent ideas here to concider. Is there a car charger i could hard wire in? what is this switch everyone is talking about that surge protects? Also Would WiFi via a cell phone be viable/affordable in my car? I have never even thought about it.

This project is out of my comfort zone and i would appreciate ANY help i can get. thank you all!
Cheers!

-Logan

[loganthegun]

I believe i am going with this for a car power solution;
5A Switch-Mode External UBEC Module-UBEC, 8s, 5A, 40cm - (Premium Quality)
Is this a huge mistake? thoughts?

Cheers!
- Logan

[abishur]

I believe i am going with this for a car power solution;
5A Switch-Mode External UBEC Module-UBEC, 8s, 5A, 40cm - (Premium Quality)
Is this a huge mistake? thoughts?

Cheers!
- Logan

I'd like to see a product sheet before giving too definitive an answer, but 5A would be more than enough to power the pi. I would check the datasheet to see what the output voltage is based on the current and input voltage. I'm guessing you're not connecting straight to your car battery, most of the UBECs I've seen has a max input voltage around 23V, finding a spare fuse slot to tap to provide 12V shouldn't be too hard, but then you have to be careful that the output voltage when the Pi is drawing minimal power (theoretically < 1A depending on what you connect to it) isn't around 5.5V, a very real possibility on the higher current ubecs.

All of which really is to say, read the datasheet carefully

[loganthegun]

That is awesome info. Thank you! This is a rough up of what I'm planning... Thoughts?

http://imgur.com/z52TN41

[abishur]

My only thought is you'll end up consuming a 12v outlet that way. I've used a great thing in the past called "add a fuse". Basically it lets you connect two fuses to one fuse holder so you can safely power devices without pulling new wires through the fire shield of your car. They're pretty cheep ( less than 10 USD), and would give you a dedicated power source.

Other than that it looks good, maybe? I'm big on detailed schematics so without seeing fuse ratings, etc I'm reluctant to say "go for it!"

My only real question is why there is a power inverter connected up to the USB ports of the pi?

[loganthegun]

Awesome i shall spin the wheel! The "usb" on my chart is a USB power hub which will be powered by the inverter but is expanding upon the Pi by way of a usb cord. I am going to run extras from the hub (all those little green lines) such as touch-pad dongle, WiFi, external hard drive, ex. and i didn't want to run all that power through the Pi. I have been reading a lot about how bad it is to run all that power through.

I am ok with burning a car lighter. I just quit and there are 5 in the car. Also that far left power wire is a zero gauge that is already powering my amp straight from the battery and will be a snap to tap.

Thanks!

[loganthegun]

Abishur, Huzzah the install is complete! Success on hard wiring an inverter. All seems well with the USB hub and the pi except one thing..the USB to the screen is back feeding power! (I am assuming this is bad...) when it boots the screen is white with slightly shifting pixel lines and then nothing. What should i do to trouble shoot this? I have tried powering the Pi seperatly and through the USB hub but to no avail.

[abishur]

....ll seems well with the USB hub and the pi except one thing..the USB to the screen is back feeding power! (I am assuming this is bad...) when it boots the screen is white with slightly shifting pixel lines and then nothing. What should i do to trouble shoot this?

Ah, sorry I should have mentioned that, sometimes I forget what people do and don't automagically know

Some USB hubs backpower down the USB "input" port. This isn't necessarily a bad thing, but I personally don't think it's a great thing either. The Pi has some nice protection circuitry when you only use the microUSB plug, and letting things backfeed down a regular USB port bypasses that circuit protection (Or at least it does on the Models A and B, I'm not sure about the B+ yet). Anyways, you can either let it run as is and hope that nothing causes the USB hub to suddenly provide more than 5v DC, or you can do a couple different things

1) Do some modification to the usb cable and cut the 5V wire (usually red) so that the USB hub's power can't reach the Pi
2) Buy a "data-only" usb cable which has the power line already cut for you
3) Swap out the hub for one that doesn't back power http://elinux.org/RPi_Powered_USB_Hubs# ... cific_Hubs lists two know hubs not to back power specifically made for the pi, but they also have a huge list on that page and you might be able to find a different one that doesn't back power.

[loganthegun]

Thank you!
I have solved the back feed and the project rolls on! The latest and greatest is a problem getting the Pi to talk to my existing head unit. Its a Chinese touch screen multifunction deal and it does not seem to like the Pi. So far i have tried;
1) a USB from the Pi to the head unit
2) a HDMI to A/V convertor
and the next thing i am trying is a USB to A/V but i am almost done with trying...
I have an old cheep tablet laying around and i am thinking of just using it with a Eithernet crossover cable instead of that bullhonkey.
But if you can help me solve the connection problem i would be eternally grateful!

Cheers,
Logan