Navigation not working on tricopter

Hi all,

i have big problem with navigation modes. Here is my setup:

APM 1280,

Oilpan v2,


GPS mtk16,

sw version 2.0.39b.

tricopter configured to X orientation

When i run test on compass and gps in terminal everything works OK.

In field after GPS lock, takeoff and short stabilized flight  away (100meters) i switched to RTL mode and nothing happens. Tricopter holds altitude but wind takes it slowly away. Not moving to home at all.

The same situation when i switch to AUTO mode with some waypoints loaded.

The log is for me puzzle, even if i have enabled all in log file. Most strange is that the CMD is in the file only once even if i switched modes several times. In the log file i can't find GPS records. Could it mean the ACM software is not communicating with GPS?

I attached also the log file if anybody interrested.

2011-09-02 06-30 1.log

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  • Now I found the problem - when I predefine GPS_PROTOCOL to GPS_PROTOCOL_MTK16 in APM_Config.h and use such modified ACM software, board has then problem to communicate with GPS after plain start. Only after reset it starts communicate with GPS.

    When I leave GPS_PROTOCOL on GPS_PROTOCOL_AUTO then red led on oilpan starts blinking right after powering up and no more reset is required.

    I used to predefine GPS_PROTOCOL to GPS_PROTOCOL_MTK16 to save some memory space when I optimized APM software since latest versions of APM exceeds memory room of 1280 APM  board.

    With ACM software there is no problem with space room on 1280 board version so far so I can live with GPS_PROTOCOL_AUTO.

    Now I don't know if the same problem appears on APM software 2.24 since for now I'm only interested in ACM and tricopter flying. 

  • Now  I discovered why the navi modes were not working - GPS had lock(blue LED solid) but ACM hadn't (red LED on OILPAN was even not blinking).

    I have to reset board after powering up the ACM then red LED on OILPAN starts blinking and when GPS blue LED became solid, red LED on OILPAN stays solid too.

    Thought this error was long ago solved (note I have mtk GPS with latest firmware). Can somebody bring ray of light to this puzzle? Why I have to reset ACM after powering up to make communication between ACM and GPS possible?


    Today I have tested RTL and AUTO modes on the field - working flawlessly. Only issue is - moving between waypoints and RTL is too slow ;o(. This is but question of PID params guess... Can't find some hint to tune up my tricopter (construction , motors and ESCs is the same like RCEXPLORERs)

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