I'm considering my first proper Arduino project. I've got a fairly cheap exercise bike. The bike is great, but the LCD readout is hopeless, and there's no way to connect it to a PC or anything. I'd like to change that.
The interface between the bike and the display unit is very simple - it looks like a standard 3.5mm audio jack, and I'm *hoping* that the signal is similarly simple. The problem is I'm not really sure if there's a safe way to figure out the signal format without blowing up my board. Can anyone recommend a circuit layout that'd let me figure out the format without causing damage to my board. All I really want to start with is to safely connect the 3.5mm jack to an analogue input and monitor the values. Is that even possible without figuring out the voltage/current with an oscilloscope first?
I'm comfortable enough with the software side, I'm just not sure where to start with the electronics.
Any help much appreciated,
How many different segments are there on the 3.5mm jack. (most have 2-3 on them)
Odds are theres an encoder on the wheel to tell the RPM of it.