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Permalink Reply by Gordon on January 5, 2013 at 3:00pm

I think you are on to something here with the MULT-CH mode.

Most of the 433MHz LRS systems also had problems with this and would only work in 7CH mode. There was a workaround for the LRS stuff which involved setting all the endpoints to use either the top or bottom half of the travel. Can't remember the exact details, never tried it myself. It was reported to work but you lost resolution by using the full stick travel with only half the pulsewidth range.

I remember reading something like, that in order to be able to tx more than 12ch ( the 8fg, 12fg etc can produce 14ch or more) the stream had to be compressed to fit into a singe frame. I think that is why JR only had 11ch for a long time.

I can also confirm that these glitches were happening in ppm-sum mode with a 12FG and TFR4 receiver.

I was also getting the glitches on ch 5. Imagine my surprise when I was doing a hand test and heard MP call out " mode changed to RTL, mode changed to stabilize". I didn't know what was going on because it was the first use of a brand new APM2.5, first use of new TFR4 and first use of ppm-sum.

Immediately ruled out the last 2 by going back to the orange receiver and separate channels I had used with the old APM1.4. Thought I had a dud board until I discovered the "motor twitching thread"

So thanks to everybody who reported and fixed the issue

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DeveloperPermalink Reply by John Arne Birkeland on January 5, 2013 at 6:12pm

If glitches also happens in PPM-passtrought mode (receiver outputting PPM-SUM directly), then the PPM encoder has nothing to do with it. Then you will have to make sure the receiver is outputting standard 8 channel PPM-sum, since that is the only one tested and supported by the PPM decoder in APM.

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Permalink Reply by Drone Savant on January 6, 2013 at 8:16am

I noticed in this video http://vimeo.com/26826657 Randy has an odd "Sudden throttle up" while using a Futaba radio. Looks like it triggers an unexpected props on lock up some how. Is this behavior something that can occur as a result of this Futaba related PPM bug we are discussing? Randy did you ever track down what caused that specifically? 

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DeveloperPermalink Reply by John Arne Birkeland on January 6, 2013 at 9:40am

No, that was most likely a APM control/mode logic flaw. I haven't been involved in that particular case, but I would be very surprised if it hasn't been fixed a long time ago.

A PPM glitch will recover the next radio input cycle, meaning that the throttle spike will only last about 1/50 of a second. Enough to get a visible shake in the copter, but nothing serious like dropping to the ground, or a runaway.

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Permalink Reply by Drone Savant on January 6, 2013 at 10:07am

gratzi for the explanation sir. 

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Permalink Reply by Josh Potter on January 5, 2013 at 6:28pm

I've seen this glitch on quads with an 8FG and an R62208 SB.  I just updated my PPM encoder and I'll keep an eye out for the problem when I put a quad back together.

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DeveloperPermalink Reply by John Arne Birkeland on January 6, 2013 at 9:45am

Great! Any feedback if very helpful and much appreciated.

Note to all, remember to specify relevant information like radio or transmitter module and receiver type when you post about a glitch.

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ModeratorPermalink Reply by Nathaniel Caner on January 13, 2013 at 6:48pm

Josh,

Have you had a chance to take your bird out and test this Tx/Rx combination with the latest PPM encoder firmware? Just to be sure what Tx mode are you using? 7ch MULT or MLT2?

Regards,

Nathaniel ~KD2DEY

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Permalink Reply by William millette on January 23, 2013 at 7:52am

i purchased 2 new apm 2.5+ units from 3dr store last week.... everything was installed on a pre existing quad test bed running perfect on the naza controller.... when apm was installed and tuned i get occassional motor spike and very occassional i get unwanted commands....  when sitting on my bench not flying every so often my gimbel will twitch.... showing its not the motors or vibrations causing this........

 

also when trying to flash the atmega chip per wiki... the unit connected by usb, installed jumper and shorted pins then trys to reconnect but fails and gives the computer the three sounds indicating failed connection..

 

so i can not flash my new apms.... now what can i do?

 

i lowered my mpuk to 20

every function works well in flight.

im running brand new futaba t8j radios with 8ch recievers.

any help would be appreciated

all my other posts went ignored so im trying it here.

 

626-789-4045 william

uav productions.... youtube

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3D RoboticsPermalink Reply by Chris Anderson on January 23, 2013 at 8:13am

William, as I responded to your identical PM, please contact tech support and ask them if you can send the boards back to be reflashed with new PPM firmware. 

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Permalink Reply by William millette on January 23, 2013 at 7:00pm

update...i found the dfu driver and installed it myself and now can connect to flipand flashed with latest hex.....

does anyone know if everything needs to be recalibrated on v2.9?

the radio or acellerameters ?

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