Is it possible to detect that there is a device connected on the other side of the cable without using any current sensor? I simply want my arduino to do something when i plug my phone to charger.
I have tried to use 4N35 without success as shown on the picture, even with some resistors.
I know i could use something like ACS7xx current sensor but i think it could be done without it.
Another way to do this would be to use DATA lines of the usb since they are pulled either HIGH or LOW but i'm not sure if i want to mess with that.
Any help or advice would be highly appreciated.
EDIT I have tried to detect the device on DATA line and it works, unfortunately only when the device is on since i need to read HIGH signal.