Car Lights

Description

A self motivated project conducted completely from scratch to mount lights under my car door for purpose of visibility/safety and the special effects. When the car door is open the lights will turn on to shine on the ground with an under-glow effect. When the car door is closed, the lights will turn off. Then when the door is open again, the lights will turn on with a new, random color. Every subsequent time the door is closed then opened, the lights will turn on with a new random color.

Hardware List

Arduino Uno
Adafruit DotStar led strip (1/2 meter)
Reed switch
1K Ohm resistor
18 gauge wire
single strand 22 gauge wire

Hardware Purpose

Arduino Uno: This is the brains of the project, everything runs from this. I used Altoids tin to encase the Arduino, cut two holes in it, ran the wires from the holes and placed the tin in holes under my dash. This hole was easily accused by removing the side panel from my car to the left of my steering wheel.

Hardware:

The reason I used an Arduino Uno vs a smaller Arduino is because I wanted to have access to the barrel connector to power the project. I power the project through a 9V battery with barrel connector. This 9V battery connector I ran though the side dash panel into fuse box which is even easier to access. So this project can be easily turned on and off by attaching and unattaching the 9V battery from the connector in the fuse box. From the Altoids tin, I have three main wires, each of which are two wires attached to each other(see picture 3 below). One wire is used for the reed switch, one side of the wire sending a voltage to the switch, and the other coming back (reed switch explained later). The other two attach to the DotStar's four wires (positive, negative, data, clock). These run straight to the Arduino where the data is on pin 13 and the clock is on pin 11. Now the positive and negative I set up differently. I used a mini breadboard and designated two rows to be the positive and the negative rows. So the positive and negative go to the appropriate rows. The reed switch also attaches its positive and negative to these rows.

Software:

The reason I even used an Arduino at all here is so I could write code that changed the color of the lights every time the door is opened. Because I made this choice to use an Arduino, I could use this DotStar led strip instead of using a simple positive/negative led strip. I write the code specifically so it would only calculate random RGB numbers once, and not multiple times over and over while the door was closed. So whenever the reed switch was activated, the code would generate a new set of random numbers, and only do that once. These numbers are then stored until the door is opened then closed. I felt that this code was redundant, and did not have to run over and over. So in order to improve efficiency, I have it perform once per door closure.

Adafruit DotStar led strip: This piece is the star of the show. I mounted this underneath my car door so that it is hidden, and ran the wires partially up the side of the door, then hung then across the gap to connect to the car. The lights are encased in a rubber sheath to protect it from the elements. When the car door is closed, the lights are turned off; then when the car door is opened up, the lights will turn on with a random color. From the led strip are four wires: a positive, a negative, a data, and a clock. These are hooked up to the Arduino to the appropriate pins. Data on pin 13, clock in pin 11, and positive and negative going to the breadboard.
Reed Switch: A reed switch is a sensor which completes a connection every time is senses a magnetic field. This runs on one wire from the Arduino, and works the exact same way as a button. On one side of the wire I run a voltage to the reed switch, and the other side runs the completed connection to both ground, and pin 2 on the Arduino. When a magnetic field is detected, current will flow through that other side, and back to the Arduino. So what I did was use a powerful magnet, one from a hard drive, and stuck that to the door of the car, then straight across to the car, I mounted the reed switch. So whenever the car door is opened, the magnet is pulled away from the reed switch, and whenever the door is closed the magnet is right next to the reed switch. Now on the negative lead of this, I had to run two wires, one to ground and one to pin 2 of the Arduino. Starting with pin 2, this is checking for any voltage spike from the reed switch (the reed switch being connected). When it reads HIGH, (the door is closed and the magnet is next to the reed switch) the lights will turn off. And when it reads LOW, the lights turn back on. The wire runs straight to the ground to complete the circuit. This is simple enough, however to avoid a short circuit, I had to attach a 1K Ohm resistor before connecting it to ground.
18 Gauge wire: This is simple radio speaker wire. I run this from the Arduino to both the reed switch and the DotStar, using 3 3' wires to be exact. Each of these wires comes with two wires attached to each other (see picture 3).
Single Strand 22 Gauge wire: I used this wire so that I have something thicker to insert into the pins of the Arduino and the holes on the breadboard. For all the wires that need to be plugged into the Arduino/breadboard, I would solder this single strand 22 gauge wire onto the end of the 18 gauge wire and plug the single strand wire into the Arduino.

Skills used

Programming in Arduino code: Started with example code for the DotStar and wrote my own code around it.
Soldering: And a lot of it. I must've spent 4 straight hours soldering all the connections. These include: the 18 gauge wire to the reed switch, that wire to the single strand wire, that wire to the resistor then to the single strand wire, all four connections of the DotStar to the 18 gauge wire, soldering those four wires to the single strand wire.
Mounting: I first removed the the left dash panel from my car and inserted the Altoid tin. I then mounted the reed switch to the car using electrical tape to wrap the wires, and then more electrical tape to tape it to the metal of the car. Of course the reed switch can be used even when it completely encased in tape. I then wrapped all the lose wires from the DotStar in electrical tape, and mounted the light to the bottom of my car door using Gorilla double sided tape. Using the electrical tape, I taped the wires from the DotStar up the side of my car door, and hung the wire tightly across the car door gap to the car. I did this with the car door as far open as the door could go so I knew the gap would be as wide as it could be to avoid the door pulling on the wire. Using more electrical tape, I taped this wire across the weather stripping, and into a panel by the feet. This then runs up into the first panel I removed, which hides all the wires behind the scenes.

Timeline

Day 1: Start by making making my project work using a single neopixle and a button on a breadboard.
Day 2: Moved onto making my project work with the reed switch, by replacing the button with the reed switch.
Day 3: Replace the neopixel with the DotStar led strip, and make the project work on that code.
Day 4: Replace the breadboard with the wires, and make the project into something that can be mounted in the car. Solder all the joints.
Day 5: Mount the project on the car.

Problems I Ran Into

One of the problems I ran into was that the spot I mounted the lights to under my car door did not have enough room. Every time I would close the door, the lights would rub against the weather stripping. I thought that this would be fine, but after a few days of regular use, the lights got pushed off the double sided tape, and into the corner of the door. Not only this but the strip was turning itself in the rubber sheath, and it was clear that the light could potentially break if it stayed here too long.

So to fix this I moved the light to another spot under the door, a spot where the lights won't hit the weather stripping, and so far there hasn't been any wear and tear on the DotStar.

Another problem is with the power consumption. Just an hour after the project was mounted, powered on and ready to go, the battery had died. Since the projects purpose is to be on all the time and for the lights to turn on every time I open the door, having a battery that only lasts an hour won't cut it. So I trued a new, fresh battery and after another hour I ran into the same problem. So it's clear that this project takes too much power to run it.

I have not found a solution to this yet, this is still in the works. My first thought was that the Arduino takes too much to power it, and that having the Arduino running all the time would be costly. So I was thinking I would use an Arduino nano, and since it's smaller it might take less power to run it (I could be wrong, I have not done the research on this). I was then thinking that because when the door is closed and the reed switch is activated for most of the time in this project, the Arduino it forced to send 5V at all time. That means whenever the door is closed, the Arduino must cycle 5V through the reed switch for most of the time because the door is closed most of the time. This is very costly, and requires me to have to restructure the whole project. However once I find a solution to this problem, I will make the necessary adjustments.