This week I spent a lot of time on servo and video communication. Nothing works yet. My brain hurts.

Current issue with servos is there is something wrong in the duty cycle calculation. Whatever calculation is being used for the library servo code, the calculated duty cycle is out of range of the maximum. I have compared the ServoKit Library to the MotorKit Library. Both are using the same servo code, the board uses the same chip, the default frequencies are the same, so I’m not really sure why the calculation is not working. I have two parts to my next step attempt. Firstly I want to check the hardware by forcing the duty cycle to be definitely in range, just by setting the actuation range and desired angle very small and seeing if I can pick up a signal from the PWM channel on my oscilloscope. On the software side, I’m going to check the math behind the frequencies.

With the video communication, we decided that we wanted to get some form of communication up and running especially for the demo. Neither of us knew how to tackle the Linux kernel, so the easiest path available seemed to be with UDP. Eddy and I were both able to get communication between the Jetson and our PC, but we’re stuck on the encoding/decoding of the video. The suggestions on forums seem to be not working. Next step for me is to try reading through some examples in the link below and seeing if I can get it working through that. I’m trying it right now, but needed to get the status report in. Also, below is a photo of some stuff coming through UDP from my Jetson. I fixed this issue by adding a queue, but not sure if it’s the correct fix. I think the best solution is to make sure encoding and decoding are working like I mentioned.

https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%2520Linux%2520Driver%2520Package%2520Development%2520Guide%2Faccelerated_gstreamer.html%23wwpID0E0YY0HA 

So for the upcoming week, the big idea is to get everything working for the capstone demo. I’m planning on getting video communication working, the micro servo working, and determining top and bottom of the elevator, so that there is good vertical centering. I think Anna is still working on getting the microphones to detect distance properly, so I’m not sure if I’ll have the time to integrate that into the prototype as well.