This is the third iteration of my Ardupilot Mega to Hitec telemetry adapter. Adapter no longer requires modifications to APM itself, but instead connects to telemetry port of APM and it has a pass through connector for telemetry transmitter. I made PCB this time using SMD parts for smaller size:
It's possible to have the device automatically display different information based on airframe type. Currently shown vario and airspeed readings are not that useful for hexa, but for example heading might be. I just got my hexa so I've yet to decide what to show. Unfortunately compared to previous versions, it's not anymore possible to show "mAh used" reading since to my understanding that information is not sent in any mavlink message. When using different types of batteries, that information would be more useful than percentage remaining reading. Should we add mavlink message for it?
For more information about the device and sources, see http://antibore.wordpress.com/2013/02/28/showing-apm-telemetry-data-on-hitec-auroras-screen-3rd-edition/
Now if I only could get my hands on some different telemetry capable systems, I could try to make this adapter universal one...
I've also asked on the rcgroups hitec forum, but the trainer port solution is not possible :( Think it's time for a taranis tx.
@Bas Tjis: It's indeed possible to use trainer port for headtracker, since you can select which channels are overridden by student from trainer menu. It's also possible to hack for example slider switches and input headtracker position to them, but I would not go that route since it required modifying the transmitter.
I implemented the vario function for my adapter, but as far as I know, Aurora only supports alarms for battery and current readings.
Or maybe replace 2 switches with something that can be connected to a diy headtracker?
On the sensor subject: I am interested in a vario, as Im gonna use the APM in a glider. Would it be possible to let the A9 beep based on the APM barometer (here is some code already: http://www.rcgroups.com/forums/showthread.php?t=1749208)
Would it be possible to feed 2 channels (for example 1 & 2) from the headtracking to the trainer port and add it to the other channels? I could set up my controls on channel 3-9.
@Bas Tjis: The board size is now 35x40mm, but it could be reduced a bit easily. The board connects to APM like you would connect 3DR Radio or Xbee to it and it has a passthrough for telemetry transmitter.
I don't use a headtracker myself, but I have a pretty good idea how I would do it. On A9 TX module connector, there is one pin which transmits all channels in serialized pwm format (don't remember the pin number but it's easily found with oscilloscope). One needs to hijack this signal, prevent A9 from sending say channel 8 and 9 positions and instead inject headtracker X and Y positions on those channels.
Another question: will you be able to modify the A9 to support head tracking? Many people are requesting it but it looks like HITEC is focussing on the new A9X, you would be a hero ;-)
Thanks for the offer. I will consider it once I have the APM.
Do you have any pictures of how to connect it up and the size of the board?
@Bas Tjis: And with mere 25€, I can send you one ready made =)
Cool, just ordered an APM, would also like to have something like this for my A9 :)
VCC. You can connect VCC and AVCC together, but as ADC is not used, it's not that important.