Hi there, hello to everyone. Just arriving here. Got a few karma drones on a blackfriday on November.
Seems nobody is trying to do some reversing on this drone.
There is hardly nothing documented out there.
Last week I had time to start working on one.
First impressions:
1) Main CPU seems a STM32. Although there is a black resin around it, there is a STM32_SWD pads just beside it. This is the Serial Wire Debug port of this CPU.
Has anyone tried to connect a STM debugger to this CPU? There is a soldered miniKK conector with the label STMDBG UART and a XI2C line.
2) There is an AMOTECH GPR7 just left of main CPU. Looks like JATG pads are also there. Can’t tell if they are wired with GPS or CPU. Anyone knows? There is also pads for GPS UART and GPS USB.
3) There is a shielded area I haven’t open yet. Will try to get a dead board so I won’t risk damaging my working unit. On the bottom of it there is a connector labeled DM_368 DBG. I guess under these shielding lives a Texas Instruments TMS320DM368 DaVinci doing the heavy work of encoding and compressing h.264 video. There are two red wires acting as antenna, at first I tough they are GPS Antenas, but now I think they are the antennas transmitting video on 2.4 ghz band.
I think this because the DM368 itself won’t need any shielding. The shielding is only needed because there is also a transmitter coupled with DM368 encoder.
Anyone knows if karma uses one radio link for control and other for video? That would make sense and avoid a lot of trouble on the project (like using upper layer protocol priorities schema to avoid delay in comands if video is using too much bandwidth).
But if that’s the case, then these are poorly designed antennas that explains why video behave bad once we go a little far, or the noise level on 2.4 ghz spectrum is high.
4) On the bottom chassis there is another board that seems the control one. Another shielded area, linked with two X (looks like circular polarity antennas), built in the lower chassis. Much better antennas than the ones that I think are used for video link. These modem board is linked by a flat cable to the main board, and right beside it are pads with a label MODEM. Looks like a serial pad. Has anyone tried listening to it? If the modem board is speaking serial with the main CPU, it should be easy to send commands from another onboard CPU, adding collision avoidance and other pretty stuff. Anyone?