I'm trying to create an RC transmitter that is partially based on a USB host shield 2.0. The device I want to connect is a PS4 controller through a bluetooth dongle. Everything works as expected when the arduino is powered up while being connected to the computer using USB.
I've since attached a battery and have found that everything continues to work when the USB is disconnected to the computer.
The confusing part is that when the arduino is powered up from the battery without the USB plugged into the computer it no longer connects to the PS4 controller.
The example code for controlling the PS4 controller has a commented line about USB CDC serial connection.
I was wondering if anybody could explain why the Arduino must communicate with the PC before the bluetooth shield can work properly and if there is any work around so I can connect the controller without needing a computer.
Here is the github site that includes libraries and examples I'm working from as well as info about the bluetooth shield I'm using. GitHub - felis/USB_Host_Shield_2.0: Revision 2.0 of USB Host Library for Arduino.