Arduino automobile hacks

Hi all! I'm super excited, my first post! I have successfully completed almost all of the the starter projects from Arduino starter kit an I am ready to move on to something that is actually useful! 8)

Arduino automobile hacks: Here are the 5 things I want to accomplish: Automatic lights - turn on when its dark, turn off when its light Parts list: 1. relay 2. Photocell 3. Manual 3 way switch - off, on, auto 4. 10k ohm resistor

Outside/Inside temperature display 1. X2 waterproof digital temperature sensor 2. cm1602c lcd module 3. 10k ohm resistor 4. 220 ohm resistor

Knock to Unlock - unlocks doors when secret knock on driver side window 1. Piezo electric speaker 2. relay

Unlock doors by proximity 1. 3 Meter read distance - RFID/Transponder/NFC/Bluetooth reader (TBD) - similar to automated turnpike tolls 2. Active fob 3. Relay

Compass 1. cm1602c lcd module 2. Compass sensor

Do to my limited experience I am seeking for a bit of help and some fresh eyes to look over my project to spot any potential gaps in my logic and parts list before I order everything. I already have the common hobbyist (I build RC Model Airplanes) items, solder, wire, connectors, heat shrink, batteries.

Thanks! :)

Hi and welcome,

Your projects seem possible.

Relays... If you don't want to use transistors, you will need DC solid state relays. With a magnetic/coil relay you'll need a transistor since they draw more current as your arduino can handle.

With multiple coil relays an uln2803-chip may be nice since it has ttl-level inputs and can be connected directly to your arduino-pins. You'll need an flyback diode using coil relays, which is integrated in the chip as well.

Temperature sensor, I haven't worked with an X2, but I guess you could use most kinds of temperature sensors. Making 'm waterproof isn't hard and can be done with glue, epoxy or even 3-4 layers of paint.

RFID, 3 meters is quite a lot, a reader may be quite expensive. Using 2 bluetooth modules or an 433MHz transmitter+receiver is probably less expensive.

Compass, you can buy a single compass, but for a few bucks more you can buy a 9 or 10 DOF-module, housing compass, accelerometer and gyroscope. Besides direction you could record your driving style as well.If you live in the mountains, you can measure altitude as well.

Automatic lights, it will probably require more... of your attention as usual. If it's still light when you park your car and the switch is still in automatic-mode, you may need to ask your neighbours to push-start the car next morning.....

Relays was the first thing to come to mind when I thought about switching on lights… but now that I think about it the headlight switch in my care is most likely connected to a relay. I will have to measure the amperage across the switch I am pretty sure it just a +12v signal so I could use a transistor. What would be the easier route?

The X2 meant times two as in I need two temps sensors. I just ordered these off Ebay:

This $55 “RF8315RT Active RFID 8 Meters Transmitter and Receiver” is good upto 8 meters but it does not work within 1 meter :frowning:

The whole point of the RFID is so I can walk up to my car and it unlocks with no intervention and when I leave the car it locks with no intervention. Is it possible to us Bluetooth or 433Mhz TxRx in this fashion?

Thanks for the info about the “9 or 10 DOF-module”… this could come in handy in the future when I use the Arduino to drive the car :slight_smile:

The headlight portion of the code will be blocked off in an if statement checking for +12v from behind the cigarette lighter plug which turns off when the car shuts off so I don’t think I will have any issues there. I also will program it to wait 10 minutes before turning the lights on when it gets a “dark” signal. This way it will not flicker when its on the threshold.

I guess my only other worry is the Arduino will drain the car battery after a week of no use. I was reading about code to make it enter low power states but I need to research that more.

Thanks for the help Simpson_Jr!