"Unlike other meters on the market this project uses Bluetooth 4.0 to communicate with a phone to display the readings the sensor is picking up."
There is a lot of information about color meters available online, not being a photographer myself most of the following is collected from various sources online.
Color meters are not exposure meters. Their main function is "pre-production" light source color control.
However in both photography and video knowing the color temperature of the shoot beforehand can help in doing digital white balance later during post-processing.
Color temperatures over 5,000K are called cool colors (bluish white), while lower color temperatures (2,700–3,000 K) are called warm colors (yellowish white through red).
The color temperature of daylight is 5,500K and knowing if the current color temperature is above or bellow this will allow to later adjust for it both during and after the picture taken or video has been filmed.
With the help of a color meter the average color from multiple light sources both indoor and outdoors can be determined. As light varies with location realtime data from a meter can help locate both good and bad areas for filming.
Step 1: Parts List
The project casing is 3D printed.
The other parts are:
A generic portable USB Battery
Arduino Jumper Cables (x4)
Total cost for parts excluding 3d printed parts and battery is $43.
In comparison a professional color meter will cost well above $1000. (Since I dont own one, I cant make a comparison to the accuracy though).
Step 2: Building
The color sensor is using I2C for communication so wiring is straight forward 3v from sensor to 3.3v on the Arduino, Ground to common ground, SCL to I2C Clock and SDA to I2C Data.
The current source code is using the default example called "tcs34725autorange", I've only added a few extra characters to the return strings in order to parse it easier on the Android side.
You can follow the wiki for the Bluno about changing the name the bluetooth is broadcasting. After which communication is straightforward from the Android app, select the device and thats about it.
Step 3: 3D Printing
You might have to modify the battery connector to match whatever battery you have. It will screw on the board. I've made all the holes in the 3d print use 10mm M3 bolts and nuts.
Step 4: Android App
The android app is just the example Android app provided for the Arduino Bluetooth board. The app works more as a proof of concept at this stage. I only added a marker character into the Arduino code so the Android app could clear the screen instead of adding to the log. As you can see different light sources give corresponding readings.
Step 5: All the Files for the Project
Here are the Arduino Code, Android Code and 3D print STL files.