Discussions

APM GPS issue

Posted by Paul Thompson on October 4, 2010 at 9:25pm

Hi,  I have been setting up the APM+oilpan with MediaTek GPS with the public Beta. I am not geting a GPS lock signal displayed from the ABC led's. But it will get a GPS lock with lat. and long. displayed in the CLI when testing via USB in dump mode. Only geting a constant flash from the ABC led's in fly mode after IMU Calibration. Is there anything simple I have missed here?

 

Cheers Paul

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –
Follow

Replies

  • Andre S October 8, 2010 at 10:45am
    I also did not get any GPS data (although the adapter board signalled a lock) and I tried about 10 times power cycling the board. Then I noticed that the GPS_MTK library has been changed (now AP_GPS_MTK) and that somebody had removed the delay in the Init function. Now I changed the init to contain
    delay(500);
    _port->print(MTK_SET_BINARY);
    delay(500);
    _port->print(MTK_SET_BINARY);
    delay(500);
    _port->print(MTK_SET_BINARY);
    delay(500);
    _port->print(MTK_OUTPUT_4HZ);
    and (you can call me crazy for it) it worked on the first attempt.
  • Paul Thompson October 6, 2010 at 12:47am
    The SJ1 is bridged with solder, and It has been running off the ESC's BEC. The lights on APM are indicating as they should and everything else seems to be fuctioning well when connected to the CLI. just cant get the GPS fix lights on initial powerup.

    I measured the voltage between 1 and 8 pin on the MediaTek and I am getting 3.12v.
    If I boot the board up and wait for the 3DFIX light on the MTek, I can then hit the reset button on the oilpan, let the it reboot and it will then show a GPS Lock. It seems to only not get the lock from an initial powerup.

    Chris:
    Thanks for doing that, I was not sure whether to do that or not, I will do so in future.

    Cheers Paul
  • Admin
    Thomas J Coyle III October 5, 2010 at 5:19pm
    Paul,

    Measure the voltage between pins 1 & 8 on the MediaTek GPS. If it is less than 3.12 vdc then you are probably going to have problems getting a lock when on the UBEC.
    You might try bending the little ears (tabs) on the back end of the negative plate of the battery holder under the interface board. Sometimes the ears get pushed into the positive plate of the battery holder and drop the regulator voltage below the allowable limit.
    The regulator on my MediaTek was putting out 3.06 vdc and I was having trouble maintaining a reliable lock. After bending the ears away from the positive plate of the battery holder with my finger nail, I was able to always get a reliable lock. However, I sent the MediaTek GPS back to Jordi because 3.06 vdc is way out of spec and my other two MediaTek GPS/interface boards read 3.12 vdc or higher and always reliably lock.

    Regards,
    TCIII
  • Paul Thompson October 5, 2010 at 12:53am
    Have just found out it will boot up correctly and get GPS lock showing on the ABC led's when powered from the USB with the slider switch set to fly. Just won't get the lock indication when powered via the reciever.
  • Paul Thompson October 5, 2010 at 12:11am
    Ok, at least its working in the CLI test, the ABC Led's are solid during the test, But still only getting the flashing ABC's during normal fly mode, Have had it on outside for over 30mins with no luck
  • 3D Robotics
    Chris Anderson October 4, 2010 at 9:57pm
    I'm not following. What does "dump mode" mean? Is your LED sold on the GPS module itself?
This reply was deleted.

Activity