Where to connect ppm reciever to the board?

[Max]

I just noticed that timecop's original PPM code used a guard pulse length of only 2.7ms. Was there any particular reason it was changed to 3.5ms? Isn't that likely to cause problems with other systems besides FrSky?

Anyone still reading this thread?

-Max

[GoFaster]

[SuperSharpShooter]

Is anyone using the FRSKY in PPM mode with the new 27ms frame length firmware (allowing all 8 channels to be used)? Do changes need to be made to the AQ firmware to use it with this firmware?

More details on the new firmware over at diydrones topic "why-frsky-cppm-signal-is-so-disappointing"

[Max]

It's on my list to try out... but it's working fine for me with the old firmware, so I'm loathe to change anything. See a few posts back about using FrSky CPPM with 8 channels. I'd be curious to know how well the 27ms version works with multicopters... probably fine since we don't really need super-fast response (unless you're Warthox I guess ).

-Max

[SuperSharpShooter]

I've been using the 27ms frsky firmware and it seems to work as far as I can tell.

Do I need to change the guard pulse length at all? Is the default in r76 3.5 or 2.7?

[Max]

The default guard pulse length in r76 is 3.5.

To make sure it's working properly, do a logging session on the bench with motors/ESCs disconnected. Slowly move ALL your control sticks/switches to their maximum positions/values, and then down to minimum. Do this a few times, and then check the AQ log RADIO_QUALITY value. It should be a flat line at 100.

As far as I know, you'd be the first to carry out such a test. So please let us know how it goes. If it works with 3.5, then 2.7 shouldn't be a problem either, but again it would be great to verify that.

-Max

[SuperSharpShooter]

Just did that, and can confirm that radio quality stays flat at 100 with all channels simultaneously low, or high.

[Max]

That's great, thanks for testing! We'll update the docs on this ASAP.

-Max

[Max]

I've updated one of my D8R-XP FrSky receivers with the 27ms PPM firmware and tested with AQ. My results are not as good...

Below is a screencap of live radio_quality value over 20s @50Hz. As you can see, it "wanders" all over, though it never drops below ~65, and typically stays above 85. The radio_quality looks the same whether I'm moving any channels or not (and no difference at max. channel values). Tried with r76 and r78, no difference. Another D8R-XP used with this exact test setup, with the older 18ms FrSky firmware, shows a steady radio_quality of 99. Also, the Rx I updated worked fine before the update.

SSS, I'm curious about your setup, so we can compare notes. I've only tried updating one Rx so far.

Anyone else using FrSky 27ms PPM?

Thanks,
-Max

[SuperSharpShooter]

My receivers are actually D8R-II+'s but I understand that hardware-wise they're identical to the XP (And I flashed it with the XP firmware)

I don't know where the problem could be with yours. You don't have the ppm signal wire coming close to anything else between the AQ board and the RX?

When I tested mine, I had the autoquad board powered by a 4s lipo on the bench, and the only other thing connected was the receiver. - this graph is from when I took all channels to the extremes both ways.