Embedded Linux for automotive

There's nothing *listed* here that places particular constraints on whether the board runs in a vehicle or on a desktop -- other than power (assuming you want to get that from the vehicle itself).

Are you intending on *using* these I/O's in ways that are intimately involved with that automotive environment? (electrical noise, temperature extremes, etc.)

If you have uses in mind for those I/O's that are intimately tied to that environment (e.g., under the hood), you may have to. If, OTOH, you just want to plug a "box" into the lighter socket (showing my age, here... I know they don't call it that anymore :< ) and be able to "listen to music" (audio in/out) or transfer data to a laptop on the passenger seat (ethernet), then you have lots more possibilities (the power connection being the only real issue to address). Many "development kits" would fit the bill if power was addressed (e.g.,

*in* the "power connector")

Ah... that changes the mix, a bit.

Huh? Here (US) most vehicles are 12VDC powered. Most of your stated requirements can be addressed with a 5V-powered board (e.g., derive power from the USB jack present in many newer vehicles -- even if you never transfer any *data* over that connection!)

Perhaps his system is for larger vehicles (lorries, trucks, etc.), which are usually 24V rather than 12V?

Anyway, if you are powering from a car or truck's electrical system, remember that the 12V or 24V supply varies substantially depending on the state of the battery, and the charge from the alternator. To be safe for use in a 24V truck system, you need to accept ranges from 18V to 36V, and be ready for a lot of high spikes (such as when using the starter motor).

For vehicle mounted system, you need to consider at least

• Vibration, check for PCB and connector support

• Dust

• Temperature range, does the clock oscillator start at -40 C. How does it handle temperatures much above +50 C when the vehicle is parked in the sun ?

• Condensation: do you need coated PCBs, how is moisture drained out of the box

• Input voltage protection

Starting a big cold diesel may cause a severe drop of the battery voltage. I would suggest after the input voltage filtration a series diode, a _big_ electrolytic capacitor rated at 35 V and specified for high temperatures.

After that a DC/DC converter to 5 V or whatever the PCB needs. Check that the converter minimum voltage is low (say 8..12 V) so that it can fully utilize the energy stored in the capacitor.

The smaller the PCB current consumption, the longer the capacitor charge will last or you can use a smaller capacitor. A small power consumption will also help in cooling the system at high temperatures.

In addition to engine start voltage drops, this diode, capacitor, converter circuit also makes it easy to perform an orderly shutdown in case the main +24 V is lost. Of course, you need a direct, filtered feed from the 24 V supply line to start the shutdown sequence to save files etc.

check the beagle board.

Ciao Jack

--
Yoda of Borg am I! Assimilated shall you be! Futile resistance is, hmm?

Infact, I need a ready-to-use solution. One that includes a suitable power supply, mainboard, connectors and so on.

Yes, I have 24V battery and I need a ready-to-use DC/DC power supply for automotive application. Maybe one product that reads the ignition signal and automatically power-on/off the board.

I think that is going to be hard to find. The power supply should not be a big deal. Finding one with a shutdown signal shouldn't be too hard. But finding all this bundled up in one unit will be a bit tough.

I worked on a unit for military apps and the PSU requirement was mostly driven by the environment encountered in vehicles. The spec on the input voltage was up to 30 volts continuous (or thereabouts) but the surge was for 100 volts. When a starter is disengaged there is a huge spike of voltage produced by the coil which arcs across the contacts and travels throughout the power system. They call this "load dump". It should not be ignored. Even in a 12 volt system the load dump can be over 50 volts.

What are your other requirements? Would you be happy with something like a Beagle board or a raspberry Pi? Or do you need something with more performance like a PC motherboard in an ITX form factor?

--

Rick

Am 20.05.2015 um 23:26 schrieb pozz:

So get one. Car PCs are available to all kinds of specifications.

What are you going to do with the embedded hardware?

w..

It's unclear as to whether or not the OP wants a piece of kit that will become *part* of the vehicle or be used *with* the vehicle.

E.g., I can plug an iPod into the USB connector (saves me the hassle of having to deal with the nastiness of the auto's power source!!) and *use* that device most of the time the car would be "fit for occupancy".

OTOH, an ECM that sits in the vehicle (under the hood?) has entirely different requirements as to operability.

on "field" wiring as well as power entry (including polarity reversal)

Again, OP hasn't claimed what his actual requirements might be. Is there rotating media involved? What sort of power consumption? Displays? etc.

It's a BIG win if you can just run a system from a USB port present in most modern vehicles. Let the vehicle manufacturer deal with providing "clean" 5V (in some set of circumstances... e.g., may deliberately break this connection during starting, etc.)

There are many companies that have in-vehicle embedded PC with this type of requirements. For example, AEV-6312 from AAEON. Here the manual.

ftp://data.aaeon.com.tw/DOWNLOAD/MANUAL/AEV-6312%20Manual%202nd%20Ed.pdf

The PSU is compatible with in-vehicle battery and provides an ACC input signal for automatic power-on/shutdown. It is compatible with 12V and

24V systems. I don't know if it is able to support high voltage spikes during engine starting.

There is also some specific in-vehicle PSUs, for example this one:

It is compatible with 12V systems only, but it provides everything we need (at least, on the written specification). The output is ATX compatible.

I don't need high performance, but I don't want to have a restricted platform. Moreover, with BeagleBoard and Raspberry I need to find a suitable enclosure too.

It will be installed in the vehicle.

The power source should be the vehicle battery, actually 24Vdc. It could be nice if I have a platform compatible with 12Vdc too.

No display, no rotating media, only processing.

I know, but I can access only to the battery.

But I have to find a suitable enclosure and PSU and I have to make cable assembly...

Any suggestions?

I'm unclear. What about your requirements have you not found?

--

Rick

That seems to have only line-out but not line-in as you required.

It is strange that no IP class was given for that box, but I guess that it would be sufficient to survive in the cabin.

Standard connectors are used, so unused connectors should have dummy plugs to protect against dust. The USB connectors do not have any strong locking, so unless the cables are well supported, the plugs might fall out. The RJ-45 locking is not very reliable in such environment.

No power consumption was given in that manual, neither for active state nor low power modes. Unless the computer is powered down by the ignition switch, forgetting the computer on for the weekend and the battery might be drained, if the active consumption is high. However, the heat sink finns are quite flimsy, so the power consumption can't be too high at the rated +50 C temperature.

In-vechile computers can be quite expensive, sometimes in the $1000 to $2000 range.

And by 'ready for a lot' we mean 'load-dump-resistant', i.e. able to survive 120V for 400 ms

"Load dump" resistance is an official requirement for car electronics because it can occur with an intermittent battery connection while the alternator is charging it at a maximum rate.