I figured out how to successfully drive a large LED bank with external power by the same circuit that powers the "C" LED on the APM 1.4 shield.  I am thinking of putting together a how-to Blog post with the circuit, but I'm just wondering if there is any interest first?


Basically just using a simple MOSFET triggered off a pin on the IMU shield, you can drive a virtually unlimited load while drawing "virtually zero" amps on the APM board.


The idea behind it was that I can't see the LED's when the APM is in my heli.  I wanted external LED's to signal armed/disarmed.  I'm going to be using the same LED's for navigation lights.


I figure you quad guys might be interested too?

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  • 100KM

    Hi Robert,

    There has already been some effort on that subject.  I've started a blog on my showleds (the ones that marco was also using) but was waiting for a good oportunity to make a video of them in the dark before I publish it.

    I basically uses a ULN2803 darlington transistor array chip (less then $2), driven by 8 outputs of the oilpan (PortK). The idea is based on work from Max Levine in this post : http://diydrones.com/profiles/blogs/321-blink

    There is some work scattered around, like here : http://diydrones.com/forum/topics/led-lightshow-for-arducopter-hexa

    and here : http://diydrones.com/forum/topics/arducopter-pid-led-frame-lights

    and here : http://diydrones.com/forum/topics/motor-mount-led-s-latest-firmware...

    So a how-to blog where all the led stuff is centralised would be a very good think in my opinion.  I'll make one eventually, unless you beat me to it :-)

    I was also thinking of incorporating the gps status led into this, but haven't done so.  Feel free to base yourself on my code for that if you like (as long as you give me credit for the original)

    Below are the latest usercode files for the showleds.


  • So could this work on the GPS fix light as well? I thought the GPS light was "C" and the Armed was "A"?

  • I'm using the relay as described here, but will use a FET with the APM2 board, given the lack of relay.

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