LEDs / GPS / Arming Confusion

Hey all,

i am a little bit confused regarding the leds of my apm. I use the APM 2.6 and the ublox gps module. As far as i understood the blue led on the apm 2.6 will blink if there is a gps fix.But shouldn't there also be a blue led on the gps module? There is only a red one at the moment. What i also do not understand: Will the apm arm without a valid gps signal? I was able to arm my copter with the blue led on the apm blinking and no blue led on the ublox.

if i take a look at my logs i can see a "0" at ”Nsats" ...

thanks a lot,


p.s:  I did not yet understand the difference between a solid bue led on the apm and a blinking one. Can anybody please explain?

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  • It is far easier to understand what the APM is doing if you connect LEDs to output A6 & A7.

    One is the GPS status and the other the arm status.

    I use these outputs via reed relays to drive LED strips at the front and back of my quad. Blue at the front (GPS status) and red at the back (arm status).

    If you use these outputs - slow GPS flashing means no fix.

    Fast flash means partial fix (I forget the correct term)

    Solid blue means good GPS.

    Red arm status - flash is not ready or un-armed

    Solid on means armed.

    If you have the power module the red LEDs will flash fast when the battery is getting low.

    It flashes the blue GPS LEDs when it reaches a waypoint on an auto mission.

    As they feed the LED strips it is easy to see them from the ground.

    • Hey Alan,

      just wanted to say thank you! I bought a 2803 shift register and made a test with led strips yesterday. It works awesome! Just for future reference if someone is searching, too: I needed to change led_mode in the parameter list to 11 to make it work ....



      • Good news.

        On mine I didn't need to change that setting, I guess it must have been set already by the supplier.


    • Hey alan,

      thank you very much for your in-depth explanation and the hint with the A6 & A7. Thats an awesome idea and i am going to add leds to this. How do you use the reed relay? Won't i need microcontrolling for this? I already have red leds on the back and if i understood how to use a relay with the apm that would be awesome ...

      Would it work if i connect one led directly (i guess there will be 5 v on the a6 and a7)?

      thanks a lot

      • Yes, you can connect a single LED or two directly, there is just not enough power to drive the strips.

        I use the APM outputs to drive 2x 5v reed relays, which then switch the power to the LED strips.

This reply was deleted.


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