Before searching my attic for the CC2650 SensorTag I should have lying around, I decided to see what one of the iOS apps from Nordic Semiconductors could tell me. I installed the nRF Connect app on my iPhone, opened it up and powered up the original Guitar Hero Live guitar.

I quickly noticed a characteristic with a very long hexadecimal value and noticed that some of the bits would change when buttons were pressed or when the orientation would change (sensor value of the accelerometer I suppose).

However, this value contains way more bits than the device has buttons. I also noticed that the value can be written too, so I'm guessing this is also used to control the LEDs and possibly other functions on the guitar.

For creating my own game, this would be enough information to get started. However, if I want to create my own, I might still need to do something with the other bits. I reckon I still have to find my SensorTag in one of the moving boxes.