This requires being able to listen into those commands, however. With protocols such as SPI, Serial, Parallel and i2c, you can listen in with any logic analyzer or oscilloscope. USB is fast/complex enough to require its own kind of logic analyzer. The one we'll be using is called the Beagle480 from TotalPhase. This is the 'high speed' USB analyzer, which we splurged on. (For many devices, Low/Full speed is fast enough, and there's a lower cost analyzer available.)
The USB analyzer acts as a 'tap' that plugs in between the Xbox and the Kinect. A computer is conneted as well. The computer receives all the data being transmitted into memory and logs it.
On the other side, a single B connector which goes to the listening computer
The best way we've found to get the right data is to make sure to get even the 'enumeration' (initialization) packets so plug in the listening computer and start up the software. Then plug in the other end to the devices you want to sniff.
Lookin' at Logs
Since you probably don't have a USB analyzer, we have some logs that you can use to follow along with us. Visit the GitHub repository and click the **Downloads** button
Make yourself a sandwich, its a big file!
Also download the Beagle Data Center software (Mac/Win/Linux) and install it
OK now that you've eaten, lets open up the enuminit.tdc file. This is the full enumeration and initialization.
Remember that when we log the data, there's a lot of it that we can then pare down!
Let start by remembering that there are four devices (hub, camera, mic, motor) but we only need to listen to one (motor). Click on the Bus tab on the lower right
We have a few devices. Lets explore each one
If you click on Unconfigured device (0) you'll see that it was not captured. This is probably because I jiggled the cable when inserting it so it started to create a device and then got disconnected. Its not important.
You can see that there's some initialization and then just two repeating motifs: a 1 byte message alternated with a 10 byte message.
For the motor to move according to the xbox's wishes, there must be some command sent from the xbox to the kinect. Lets filter some more to see just commands sent to the device
Now we've really pared it down. There are only four commands sent to the kinect motor, since the motor moves during initialization we can just try each one. Lets look at each command
Command 1 has a bRequest of 0x06 and a wValue of 4, the wLength is 0 which means no data is written, the entire command is the Request and Value.
Now we've determined there are two request commands we can send. One is 0x06 and the other is 0x31
Time to experiment!
