Long JTAG cable for high-bandwidth logging

[japreiss]

I would like to log 500hz IMU data + internal controller states during flight. The Crazyradio doesn't have enough bandwidth for this task.

I am considering making a long 6-connector cable out of very lightweight wire so we can log to a JTAG debugger during flight. Tethers are fairly common in research labs, but they are usually larger quadcopters that can support some weight. Also I guess they are probably using Ethernet with a RaspberryPi-class computer onboard, not JTAG.

You can get some amazingly lightweight magnet wire, for example the stuff inside cheap earbud headphone cables, but I am also worried about voltage drop.

Is this idea crazy? Has anyone tried anything like this?

[tobias]

Depending on your software knowledge I think it would be easier to change the firmware to do a highly optimized transfer over the air. Currently the Crazyradio USB implementation is the limiting factor of 1000 packets per second. The radio packet can contain 30 bytes of data so by packing the IMU data you might be able to get it all into one packet.

To do this you would have to use a new CRTP port on which you will have to implement the data packing in the CF2 firmware and take care of on the cfclient side to save the data.

Could this solution work?