I'm a new motorcycle rider and I keep forgetting to turn off my indicator. So I had a thought...
I want to display in my helmet (like a hud) when an indicator is on. So some ideas and questions:
Before you begin, you may want to inquire whether modifying a motorcycle helmet is illegal. And obviously, you don't want to do anything that would make the helmet structurally unsound.
I should mention I'm just getting past the blinky light stage in terms of actual Arduino usage, though I have been programming since 1975. I can see how it might be designed, but I can't necessarily help in the actual building.
1. How to display in helmet. Doesn't need heaps of information (So don't need to go all out with optics etc). Maybe even just an LED that flashes every 10 seconds or so to let me know that it's on... Or something more fancy.
How to connect the module on the bike that has the data (ie. indicator on) with the module in the helmet.
The helmet module has to be small!
So any thoughts?
Here I would go for simplicity. You don't want anything too distracting. I would think taping two leds just under the visor opening, one on either side would be simplest. That way you aren't drilling holes in the helmet, and/or having things inside the helmet that could break off and cause problems. You would want to use diffused leds, and not the ultra-bright ones.
I would run the wires from each led to a common join point, and combine them into a phono 3.5mm (or 2.5mm) 3 element male connector, combining the two ground wires into one connection, and each light's signal wire as the other 2 connections. You then have a female wire that the helmet plugs into that runs to the Arduino. That way you can easily take off the helmet and disconnect the wires. If you forget, the wire would just come apart when you take off the helmet. Of course remembering to reconnect the wire when you put the helmet back on is a different problem.
You then hook up the Arduino on the motorcycle to the turn signals. You probably want opto-isolators between the turn signals and the Arduino (I am personally struggling with opto-isolators and relays right now). It should be a simple program to blink each light. You could also use a 555 IC and eliminate the Arduino to do the blink, but what fun is that?
In fact, if you just want an LED indicator, it should be a simple matter to hook up each LED in parallel to the indicator tail lights on your motorcycle, and you don't need an Arduino. You would need appropriate resistors so you don't burn out the LED.
Now, to get fancier, I might think about having an Arduino with a bluetooth transmitter on the bike, and a receiver on the helmet, so you don't need wires connecting things.
If you want to put an Arduino on the helmet, something like the Teensy http://www.adafruit.com/products/199 or BoArduino http://www.adafruit.com/category/19 might be small enough with an appropriate power supply. But you probably want to do things simply at first before going down this route.