This particular mod is right up there with the Android app that allows you to control the in-game smartphone with an actual smartphone. It takes quite a bit of effort to get working, it requires hardware and it's mostly a pointless novelty.
Arduino is a rather ambiguous project which cannot really be summarized well without missing much of what the whole thing is about. Arduinos are a line of open-source microcontrollers circuit boards and various attachments which enable the device to do more or less anything. The user "builds" a device using various Arduino circuit boards and add-ons, then they themselves program it to do whatever they want it to do. It can be a motion sensor. It can be a robot. It can be a card reader, a switchboard and just about anything else you want it to be.
One particular modder decided they wanted their Arduino to be a physical HUD for GTA V. Rappo stuck five simple LEDs and an LCD screen into his Arduino, wired it all up, wrote the necessary GTA V script and voila. The five LEDs work as the wanted level indicator and the LCD screen can display information such as health, armor, location, time, vehicle name, speed and it also displays the "Busted", "Wasted" and other on-screen status indicators.
While this isn't more than a novelty and is likely completely useless for anyone without moderate programming knowledge and an Arduino at hand, it really goes to show what a creative and dedicated bunch GTA V fans truly are. Rappo has included a complete tutorial on not only building the right Arduino for this mod but also for how to get it working. As you might imagine it is a tad more difficult than your usual car skin.
Do we have any Arduino enthusiasts among our readers? Have you done anything with your little machine related to GTA V?
