Hi. Okay so I have a really complicated project, I'm just going to give you the basics.
I have an Arduino micro, and I'd like to run it off my computer USB for both power and data. Simple, right. Okay, now for reasons to avoid a 3 hour explanation of what I'm doing, I'm just going to say that the Arduino needs to also run when the PC is off, for just power.
Hence, I need a back-up battery. And I do have a back-up battery, a cell phone battery that can both charge and be charged at the same time, that I hook up to the computer's PSU (so it's charged up when the PC is on, and then when off it supplies power to the Arduino).
My original plan was to tie the 5v/Grnd of the battery to the arduino, and data to PC, that way it just runs always off the battery power, but apparently that doesn't work, the PC just won't recognize the arduino and acts funky.
SO - what I need to do, is hook up the Arduino Micro to the USB, just like normal, 5v/d+/d-/grnd, but also have a battery hooked up to the arduino. Perhaps the VIN pin? And so when the PC turns off, the arduino runs off this battery.
If it's relevant, the Arduino Micro will also power a small micro servo (under 1amp) off it's 5v pin, in both battery operations.
Thanks. Had to type all that out and that's a very basic groundwork of the project. Please do not derail my thread asking what I'm doing, I can link you to my projects and such if you'd like and you can take the discussion there, this is hopefully just a basic question on back up battery power.