If the projector has a power led, you can detect when it is on without tampering with the USB connect or projector.
It does have one, but since my projector is still under warrenty, I would prefer to not modify the projector it self.
so basically you want the projector screen to roll down when you switch the projector on ?
can’t you just connect the power switches together ?
is there anything else you want the projector screen to do that would require a microcontroller ?
That’s exacly what i want to do (sorry if i was not clear, english is not my first language). I can’t use the same switch becose i’m using my multi-function remote to power up my projector and accesories.
The arduino will also trigger an stepper motor and the two micro-switch will act down and up limit.
Yes, but what’s powering the Arduino? If it’s coming from a different source with a different ground then connecting the grounds through the USB cable may be harmful. Like burst-into-flames harmful.
If you’re not sure then an optocoupler will allow the USB to be detected without connecting the ground. That probably explains the recommendation above.
The cummon ground and different source is also my concern. I’m relatively new to electronic and that’s why i was asking.
I also cheked and i do have an octocoupler (4N35 645Q), i’ll chek how this thing work. But after a quick reserch, those thing look awsome!
I’ve join a schematic of the basic setup that i had in mind, dou you guy thik it woulf work or i’m playing with fire? If so, i’ll chek if an octocoupler work, as you said.