Car controls windows lights maybe locks

So I plan to embark on one hell of a first project with the arduino, I am installing a full car PC in my truck, so far the plan is: to use an Asrock Q1900 integrated solution with 2 GB of ram(very overkill for this car PC but its what I got on hand) The OS and other on board software will be on a 30gb Kingston SSD then videos and music will be off of a WD black 500gb laptop drive in a hot swap bay. The screen will be a 6.95in tft touch screen that will be custom molded into the dash, will also have a blue tooth dongle and a blue tooth keyboard mouse combo, for data logging through the OBD-II port I may just get some off brand elms 327 knock off, for audio control I will use a Directed HMHD1000I AM/FM/HD Tuner for radio usb ports will be used for audio files and other such items along with the hot swapping drive. basic car PC things. Here's where the arduino stuff comes in, I want to control the windows, the high beams the low beams the fogs, all of my off-road lights, possibly my locks, and maybe the power mirrors. I believe it will be easy enough to control the windows, tapping into the switch with 4 relays, 1 for up, 1 for down on each window, the high and low beams are what I'm worried about, the other lights will be basic relays. How hard will this be to set up? the computer OS is windows XP with a specialized front end for the car PC.

antleo:
How hard will this be to set up?

The devices you list are all simple DC devices and the circuits to control them are simple. If you understand DC circuit design, this should be easy. If you don't, I suggest that you are not ready for this project yet. What will be far more of an issue is making all this wiring and electronics mechanically, environmentally and electrically robust. Cars are tough environments for electronics, and the last thing you want is something that glitches out when you start the engine or stops working when you go over a bump.

PeterH:

antleo:
How hard will this be to set up?

The devices you list are all simple DC devices and the circuits to control them are simple. If you understand DC circuit design, this should be easy. If you don't, I suggest that you are not ready for this project yet. What will be far more of an issue is making all this wiring and electronics mechanically, environmentally and electrically robust. Cars are tough environments for electronics, and the last thing you want is something that glitches out when you start the engine or stops working when you go over a bump.

I'm great with circuits and things of that sort, already know what I'm going to do to secure and robust. I am planning to use basic relays for all of this, but my wondering was more about the code behind it so that when I "click" the button on the computer it will send the proper information to the arduino in order to trigger the relays.

I'm also a beginner looking at installing an arduino in my car and controlling it via voice commands run through a Windows tablet. The programming is cake but I'm not sure of how to wire it. I know I can't just stick a wire into the power window switch or it'll fry the arduino board. I think I need a diode but I'm a hardware noob. Maybe we can help each other out on this.

Edit: You asked about how the computer will send the info to the arduino... I should mention that I am using an ethernet shield to create an arduino server. I think I should be able to create a private wireless network but haven't set that up yet. Using my laptop for testing, I'm hardwired into the arduino ethernet shield, sending commands as simple HTTP GET requests (e.g. http://arduinoserver:777/command?pin:9:on). The arduino parses the request parameters and supplies or removes power from the specified pin.

what you need is a wiring diagram for your vehicle.
That will show you how to interface to the cars circuitry.
Sometimes it requires a relay, other times you can get away with simple transistor,
it all depends on the cars circuits.

Sometimes you can find it on line, other times you may have to order it from
the dealer, which can be expensive, sometimes over $100 for the full manual.
Sometimes you can buddy up to one of the guys at the dealership in the shop
or parts department and they can give copies of the few pages you need.

--- bill

What i plan to do is very simple. i will be hacking into the switch. when pressed one direction the current is fed + then minus when the button is pressed the opposite way the opposite occurs. by taping into the wiring of the switch with a relay with proper polarity it will achieve the same effect. they are all very simple. these will also be the last things to go in. I want to make sure all my lights work first.

I think I'll probably need to consult a local automotive electrician before I even think about setting this up. My prototype works, but it's just lighting an LED.

While it sounds simple, sometime it isn't that simple particularly if you want to control
things when the ignition is off.

For example suppose you want to control the headlights even when the ignition is off.
In some cars the steering column switch turns on power or grounds a signal that controls a high current relay
but the high power circuit or the power to the high power relay is not active until the key is turned on.
In this situation, if you tapped into the column switch for the headlights, it wouldn't be good enough
to turn the lights on if the ignition is off.

Things like windows can be particularly tricky as those circuits often are disabled when the key is off.
In order to control those you may have to energize the window control module (if there is one) or
control the motors directly. And if you control the motors directly you must make sure that
you don't create a situation where your circut and the cars circuit can potentially "fight" over controlling
the motor. If you do, you will blow fuses or worse burn up wires.

Power locks can be a bit tricky as well. Some cars have lock control modules and some don't.
(most newer cars have modules)
Some cars don't have lock/unlock switches.
In those, the contacts are built into the lock solenoid.
You can often tap into the wires used, but some locks don't use simple on/off connections
or + or - signals for "lock" or "unlock". Some use pulses, or double pulses, and some use signal levels that invert
depending on the current state of the door lock.

It all depends on what you want to do, but these are some of the things
you may have to deal with, and having a wiring digram can make things so much easier
since you see which wire you need to tap and often what type of signal is required.

Another thing to consider, it is that often even if there is a switch, it may be considerably
easier to tap into the very same wires that go to the switch somewhere else.
This is often the case for switches/signals/wires in the steering column or inside the door.
The wiring diagram will show you the colors of the wires and usually where they run inside
the car.

--- bill