We thought we could communicate to the Robot using our Bluetooth adaptor. The thinking was that we could give the robot simple commands such as forward, reverse, right and left using the headset and that command will be sent via Bluetooth. The previous group had implemented wireless communication using a PSP controller. We wanted to use Bluetooth because it gives you a chance to learn the Bluetooth protocol for communicating between the NXT controller and your laptop. In addition, we have plans to control the laptop remotely and implement vision.
Bluetooth connection was successfully established between my laptop and the NXT brick. To learn the protocol for Bluetooth and for calling sound files and software files, you have to reference Lego Mindstorms NXT direct commands found in Appendix 2. The link for the document is shown below.
We were able call sound files and software files on the NXT brick. We implemented the following functions and drove the robot around the engineering lab using Bluetooth: forward, reverse left, right and stop. Next steps are to use speech recognition to drive the robot. The Bluetooth protocol the robot uses is shown below.
In order to call software files, or sound files, it’s important to really understand the protocol architecture. To call a software file, you have to follow the protocol shown below under the Start Program. I will cover an example for calling a left function on the NXT. The left program would be already programmed into the NXT to turn the robot left. To call the left program in the NXT you have to call left.rxe.
Figure 13: Byte Protocol