FrSky/ER9X/PPM Limit Ch. 5-8 to avoid losing sync pulse

[silverdulcet]

Hello,

I am rather new to ER9X. According to this post: http://forums.openpilot.org/topic/16146 ... ntry164004 It is possible to limit channels 5-8 to 50% and set all 8 channels SubTrim to minimum so that I can use all 8 channels without losing the sync pulse. The example in the post is with a Futaba radio. Can anyone help me replicate those settings in ER9X? I am using it to fly an Openpilot CC3D quad, so the flight controller is fine making the PPM pulses smaller. Channels 5-8 are only the 3-position Flight Mode switch and the 3 POT nobs set to adjust PID values on the CC3D. Thanks for any help you can provide.

[MikeB]

Try using the LIMITS menu.
You have an offset (sub trim) and low and high limits. These will set the centre position and the endpoints. If you set the offset to (say) -20%, the servo output centre will be moved, with the movement being stretched on the high side and compressed on the low side. You could try offset -20%, low -70% and high +30%. This will give you half the movement, but centered on 1.4mS.

-100% is a pulse of 1.0mS
0% is a pulse of 1.5mS
+100% is a pulse of 2.0 mS

So the above setting will give you a centre of 1.4mS, a low of 1.15mS and a high of 1.65mS.
Four pulses of 2.0mS and 4 of 1.65mS total 14.6mS, leaving 3.4mS for the sync pulse.

Mike.

[silverdulcet]

Just to clarify, Channels 1-4 should be left alone such as:

0.0 -100% +100%

Channels 5-8 should be as follows:

-20.0 -70% +30%

One thing I just noticed in the original post I linked to above. It appears the CC3D code requires at least a 3.8ms for the sync pulse.

[MikeB]

It wouldn't be a problem if you reduced channels 1-4 to +/- 90%, then probably set 5-8 as centre -30%, low -80% and high +20%.
1-4 will then be a maximum of 1.95mS and 5-8 1.6mS, a total fo 14.2 leaving 3.8 for the sync pulse.

You could reduce 1-4 to +/- 80%. On er9x, 80% is about the same as many commercial radios 100%.

Mike.

[silverdulcet]

Appreciate the help in figuring it out! I won't be able to test it out till the spare arms for my quad get here. I had some bad luck on my first flight. One of the props broke, just while hovering and the quad flipped over.