Just a quick question,
For my garden automation project (can be found in the exhibition section) I'm thinking of powering the arduino constantly with a wall wart but sometimes put my laptop on it to check on the progress.
Now the question is: if I run it constantly on the wall wart and then plug the usb into my laptop, will the arduino freak out because at has 2 power sources and will it reset the board?
Thanks
Alright, I'm using an UNO. The reset thing just has to do with the fact that I'm keeping time without an RTC. If there's a power failure setting the time again is no big deal, but I'd rather not have to set the time every single time i hook up my laptop.
SpencerH:
Alright, I'm using an UNO. The reset thing just has to do with the fact that I'm keeping time without an RTC. If there's a power failure setting the time again is no big deal, but I'd rather not have to set the time every single time i hook up my laptop.
There is no problem with having external power and USB power on at the same time. The boards that have an auto-voltage selector circuit will always utilize external power if it's avalible, that is it has priority over usb power. However having your arduino board reset or not is more a function of the PC software you are using and if it activates the DTR signal or not. Most arduino boards these days have the auto-reset on DTR function so if it's important that your running sketch is not reset then you might consider disabling that function and only enabling it when needing to upload a new sketch.
Lefty
Sounds good, ill already try it with a simple led sketch. External power and then hook up the usb.
Thanks for the tips!