People replied a lot while I was sleeping. I''m not going to give the same response to everyone who was asking what its for, so I'll just say it here. I want to use an arduino to spoof the 0-5V analog throttle signal on this ebike i'm building.

As best I can tell, ebike throttle units put out an analog voltage without any kind of data signal, but somehow the e-bike knows the difference between a real throttle, and one made out of an arduino, or even made out of a bench power supply. It will only run when connected to an actual ebike throttle

@MLE_online that's wild and very curious

@smellsofbikes It is! I'm stumped at the moment

@MLE_online @smellsofbikes this beat me a while ago, too. I got as far as figuring out that my throttle was a hall effect type but didn't immediately understand why that was important and so moved on...
If you figure it out please let us know :)

@Niall @smellsofbikes It shouldn't matter that it's hall effect, since it's ouputting a variable voltage between 1 and 4 VDC, but somehow it does matter. I see other people have undertaken projects using arduinos to create throttle signals on their ebikes, so this must be possible. I just don't see yet what I'm doing wrong