Installing Arduino into automobile/car to perform data display functions

so I'm fascinated now by the Arduino project stuff and I want to have it display various environment factors on an LCD in my car.

I think it'd be better to start with what I want it to do in my car: A. drive a graphical (preferably graphical) LCD such as those found on Adafruit's store. B. report on the LCD the air conditioning (A/C) temperature C. report map/compass orientation on LCD D. report altitude (I think I'd need a GPS or barometer chip, correct?) on LCD E. report outside temperature on LCD F. report the angles the car is currently at (I could use a gyro for this I think) which I think would be cool to have like aircraft have (again, on LCD) G. drive a ShiftBrite multicolor LED module

so here are my questions:

  1. what does the Arduino do when it loses power? I can't be supplying the Arduino with power 24/7/365 of course, so does the Arduino do fine at a sudden loss of power or does it 'prefer' to go through a regular shut down process each time? (this is important so I know how to wire up the Arduino to power)
  2. can a single Arduino do all those functions (of A through G)? or do I need to get two for this whole setup? I don't know how much input it can take and how much power it can supply to all that stuff
  3. what would be the best way to change the LED's brightness and/or color through the Arduino when it's in the car? is a rotary encoder what I need for that? would that allow me to just scroll/turn the encoder to cycle through all the color combinations I have programmed?
  4. is a GPS (based on the SIRF III specifically) or barometer better for altitude? I think it'd be neat to know that while driving!

so what do you all think? I'm not concerned a whole lot about budget, because I really want to dedicate a lot of time and resources to using this awesome platform if possible, so if you guys have other ideas post them and I'll see. :)

Thank you!

  1. It stops running. Unless you were in the middle of writing to EEPROM, it is not impacted.
  2. Yes. 1. You may have to supply power in parallel to the other components if you will exceed the 800mA total that the 5V regulator can source, and 3.3V, 50mA from a board equipped with an FTDI chip. Boards with 3.3V regulators may be able to source more.

Why do you need both LCD & LED displays? You may need board with higher IO like Mega1280 or 2560

  1. Brightness/color can be adusted by reading the value of 2 potentiometera as voltage dividera, then take output action from there.
  2. I think you'd be the same elevation above ground most of the time you're driving 8) GPS is limited to something like 100' of accuracy if you can read at least 4 satellite. Altimeters usually need to be told barometric pressure to correct for high/low pressure systems. I would think having barometric pressure alone would not do much for you. For example, you dial up your local airport and listen to the ATIS, hear the pressure in the area is 29.92 & temp is 59F - that is standard temperature & pressure. Your altimeter would then read 0 feet above sea level if you were actually at sea level. Do you have some other choices available there?

CrossRoads: 1. It stops running. Unless you were in the middle of writing to EEPROM, it is not impacted. 2. Yes. 1. You may have to supply power in parallel to the other components if you will exceed the 800mA total that the 5V regulator can source, and 3.3V, 50mA from a board equipped with an FTDI chip. Boards with 3.3V regulators may be able to source more.

Why do you need both LCD & LED displays? You may need board with higher IO like Mega1280 or 2560

  1. Brightness/color can be adusted by reading the value of 2 potentiometera as voltage dividera, then take output action from there.
  2. I think you'd be the same elevation above ground most of the time you're driving 8) GPS is limited to something like 100' of accuracy if you can read at least 4 satellite. Altimeters usually need to be told barometric pressure to correct for high/low pressure systems. I would think having barometric pressure alone would not do much for you. For example, you dial up your local airport and listen to the ATIS, hear the pressure in the area is 29.92 & temp is 59F - that is standard temperature & pressure. Your altimeter would then read 0 feet above sea level if you were actually at sea level. Do you have some other choices available there?

Thanks a bunch for your in-depth response. :)

i'll be very mindful of the power draw. does any company or supplier or whatever make a car power unit for the Arduino that you're aware of? or maybe one that isn't necessarily made for the Arduino but supplies ~5V DC and has the necessary filtering and protection stuff I might need?

secondly, can the Arduino put out sufficient power for those devices if it's being powered via its USB port? or does the Arduino not accept power through that? I ask because I've actually got a 12VDC dual-port USB car adapter integrated behind my dash that powers my DIY GPS integration job I did. it was simple enough and it'd probably make for tidy/tidier wiring if I could just use that second USB port and plug it into the car Arduino, but I know USB is spec'd to supply a max of 500mA, so I don't imagine that's enough, or is it? I ask because you stated the 800mA maximum draw, so I don't know if that's an issue or not.

as far as your question, "Why do you need both LCD & LED displays?" well, I should've clarified. I was referring to this multicolor LED ShiftBrite unit. all that I'd need from that is just putting out whatever color(s) at whatever brightness level. I'd probably deploy one of those LED modules behind the lower DIN pocket under my car's head unit to light that up in specific colors, which I think would look really cool, personally.

and with regards to your brightness/color info, so what you're saying is I'd probably set up 2 potentiometers, one controlling brightness, the other color? is that correct?

insofar as the altimeter is concerned, I think you're right, that'd probably be too hard (and probably more expensive than I'd be willing to take) to do and probably of little necessity. It would be cool, however, but yeah the altitude would probably be the same most of the time I'm driving, anyways. I'll forget about doing the altitude then haha.

by the way, I'm having trouble reading this datasheet to figure out just HOW much current the LCD draws: http://www.vishay.com/docs/37329/37329.pdf

...I suppose I want to look at the 'MAX.' column for a 'worst case' scenario, but which row is the one that states how much current this LCD will draw? should I add "Supply Current" + "LED Forward Current - Array" + "LED Forward Current - Edge" + "EL Power Supply Current" = ### current draw total?

This project is gonna be great, I'm really pumped. thanks for helping me!

  1. I'd go with a switching regulator, let it take care of the voltage peaks and do the switching to keep your 5V clean. Put a 100uF cap in front and a 100uF and 0.1uF after to help with any noise. 2.Power in thru USB connector is limited to 500mA as you say. The Polyfuse will see to that. However, Vin and +5v on the power connecter are not so limited. Vin will let you suck in all the current you want until the regulator overheats and shuts down until it cools off. That will depend on how much voltage it has to deal with and the current drawn. +5V has no such limit and will take all the current the board can use - this will depend on the 3.3V regulator (if you have an Uno), the FTDI chip (Duemilanove) and whatever you are sourcing/sinking thru the atmega IO pins.
  2. LED, okay, that'd be interesting.
  3. Yes. AnalogRead 0-5V on one pot & set mix of colors via PWM (such as colors at 255/128/64 for 100%/50%/25% color mix),AnalogRead on 2nd pot to further affect PWM by making the PWM a % of the 0-5V (such as halfbright would reduce the color mix to 128/64/32). The twist of the knob would be perceived differently for a linear pot vs an audio (logarithmic) taper pot. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=987-1301-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=987-1307-ND
  4. Well, maybe a little: http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=altimeter
  5. Looks like 9.75mA + 660ma + 240ma if you are running from 5V and have the LED backlight at full. Must be a bunch of them in parallel. Or use a 110Vac/400Hz inverter to drive the back light, will draw much less but be a seperate box.

You're welcome! For altitude, maybe try something from here https://buy.garmin.com/shop/shop.do?cID=158