5 volts on 3.3v arduino pin

So I am planning to use this circuit to charge a coin cell that I have powering an 3.3 volt arduino.


The circuit has a LED that is lit up while charging but since I dont plan to charge often, I wanted to reuse that LED for my actual program.

1) Can i simply connect a digital pin to that resistor led part? Or would that cause problems when I plug in the 5 volt usb power to charge?

2) What would I have to do in order to use that reuse that led? My circuit is running out of room and I need the LED in a specific place for my enclosure.


Isolate the LED cathode form the circuit and wire it up as I have shown in the diagram.


Well since the LED will not be powered by the USB when its not charging wouldnt the arduino pin have to be providing the power for it to turn on? The issue is that essentially I am providing two power sources to the LED and although generally only the arduino will be powering it, when the usb is plugged in, there will be 5 volts that will power the led but also will be applied on the digital pin of the arduino. will that damage the pin?

This would work