Discussions

Reducing cables from RX to APM

Posted by Andrew Radford on December 1, 2010 at 8:07am

Hi, I am building a arducopter and have the standard female-female servo leads to connect the RX to the APM. This amounts to a lot of wires. Is it possible to reduce this somehow? could I use a custom harness that connects power and gnd for channel 3 on the RX, but for the other 5 channels just hooks up the signal?
Is it possible to use the composite PPM signal like on the MK?

Apologies if this has been addressed before...

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Replies

The Old Flyer December 1, 2010 at 2:34pm

Andrew,

That should work very well.
Connect the power, ground, and signal from one channel (3) on the receiver to the APM with signal only connections for the rest of the channels. If you are drawing a lot of current (500ma.+) through the APM use a BEC and supply the receiver and APM separately. Then connect one channel (3) with ground and signal.
Dean Lamborn December 1, 2010 at 2:11pm

Follow the rule that if it's not there it can't break. The APM header can be left off, the plastic box and headers can be removed from the receiver and solder the wires directly. x channels plus power and ground.
Andrew Radford December 1, 2010 at 8:30am

So what's the best method for the custom harness? I can imagine you could almost do it with IDC ribbon and SIL connectors (with extra IDC connectors for the power and ground 'strays') - however on the RX side that could be difficult - I know that my futaba does not use standard IDC spacing, and besides has plastic 'walls' between servo plugs. I know some micro receivers don't have this though, they are just a bunch of exposed pins

Or are you guys just giving a haircut to 5 of the 6 servo leads?
Darren December 1, 2010 at 8:15am

I've reduced mine down to eight signal, one power, and one ground going to the receiver. I've read here recently they've gotten it also down to two output signal lines, using a middle man (chip) inline on the servo side as well.
3D Robotics

Chris Anderson December 1, 2010 at 8:15am

Yes, a custom harness like you describe works well. A lot of us are using that. You can also use short RC cables, which gets rid of a lot of the clutter.

You can also use a composite PPM signal, but unfortunately every RC brand has a different method for extracting it, so it's a bit complex. We have an onboard PPM encorder to make APM universally compatible.