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...
Last thing, VCC after the resistance is AVCC (20) or VCC (7) of MEGA328
Yes, if you connect just the adapter to receiver and supply adapter with power, telemetry menu should open in the Auroras screen and some values should be displayed. Note that if you connect the adapter to receiver after the receiver has been powered up, you need to turn of the transmitter and turn it on back again. As far as I can see, the tx detects telemetry system only when it makes first contact with the receiver.
Ok so I can omit it and my problem doen't come from that...I use arduino to progam mega 328 so I omit also all ISP part.
If I well understood, in order to test and try to identify my problem, if I unplug telemetry APM part and plugg only to Hitec optima 9, I'm suppose to see new sensor on aurora without any data ? Is it correct ?
Sorry, the FET(BUZ71) could be commented a little better. For normal use, it can be left unpopulated. Adapter supplies power to gate when APM reports solid GPS lock. I use it to turn on power of video transmitter after GPS lock has been made.
I aslo tried to have telemetry information on Aurora. I try without succes for the moment. Just to but sure about BUZ71 connections, only the gate has to be connected to PB0 of ATM328. Nothing on source or drain ?
For questions about programming Arduino and debugging serial port issues, I suggest to ask at Arduino forum, they can probably provide simpler instructions.
witch firmware did you have in your radio and reciever? (optima 7 ou 9 ? mine is optima7)
And witch version have you loaded in your apm ? and of course apm 1/2/2.5 ?
Thanks for answering Janne ^^
Great i've done 50% of the job !
I'm sure about my connections, i used your schematic for your blog.
Can you help me for compiling my code at the good speed?
I don't know how to do it :/ I'm a beginner in arduino stuff.
I don't understand this : Compile with 8MHz clock speed and when programming, check that “Divide clock by 8″ fuse on low fuse word is not programmed.
Another time, thanks a lot for spending time with me ;)
@perecastor: You got it half working, values about 5000 are debug values in code, that are shown before real data is received from apm.
Problem is in communication between apm and adapter. Double check connections, disconnect telemetry transmitter during testing. The clockspeed issue is strong suspect here, make sure to compile code with the right speed
Code uploaded, the arduino board works but values are wrong.
Distance and airspeed values are 5110. ( i have the same value when i unplug the telemetry port on the apm)
I think i have a problem apm <-> arduino ( i allready tried inverting tx/rx pin )