I'm constantly expanding my understanding of all the options and systems within the APM 2.5 by re-reading the wiki and looking for things that have changed or things that I hadn't considered before.

One thing that has recently caught my eye was the section here in the ArduPlane wiki titled

'How to flash the Atmega32U2 (PPM encoder) through USB'

The downloads section title description states

APM 2.x ArduPPM Firmware v2.3.13 (recommended update for Futaba radio users)

The wiki page was most recently updated almost a year ago (Dec 29, 2011) and doesn't specify what versions it applies to.....I don't know why this text is coming out italicized....I don't have Italics on...anyway the wiki instructions specifically refer to APM 2.0 not 2.x and the images are all of an APM 2.0 board. I realize that this is just a representation of the board at the time but it doesn't
make any reference to APM 2.5.
The downloads section here states
ArduPPM v2.3.13 ATMega32U2 firmware for APM 2.x
So is the upgrade necessary for APM 2.5 or not, and is there a list of Futaba receivers known to
n issue with the stock PPM encoder firmware? So perhaps if someone could clarify this itwould be great, also are the instructions in the wiki still applicable to an APM 2.5?
Nathaniel ~KD2DEY

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  • Hi all. How can you tell which version does the board have? Is there any software to check it? Thanks!

  • 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 ?

  • 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.

  • @John

    I spent 48 hours of my life with a pile of legitimate Futaba receivers, cables, and everything needed to rule out RFI, bad receivers, etc etc.

    The simple fact is, Futaba receivers of 8 channels or more seem to produce PWM pulses at the same, or very nearly the same, time. This throws the old PPM encoder code. I haven't asked you to fix anything, I don't fly Arduanything any more.

    "At current the MULT channel grouping is the only thing that makes sense technically."

    And that is exactly what I said in my post. Swapping for a 7ch receiver fixed the problem once and for all, swapping it for another MULT 8 channel didnt.
  • Developer

    I just ran some Futaba 8ch receiver tests using oscilloscope pass-fail detection on the ppm output signal from the 32u2. I ran the tests on a APM2.0 board with the latest ArduPPM firmware before the glitch patch (V2.2.68). Radio I used is the Futaba 9C Super radio with TM-8 FASST transmitter in 8 channel mode.


    3692580943?profile=originalThis one ran for close to 10 hours without any fail (pass counter wraps). So I think it is safe to say that the TM-8/R608FS combo does not glitch.

    Then I ran tests on the OrangeRX FASST receiver that Marco has reported problems with.

    OrangeRX FASST:

    3692580640?profile=originalI ran it for a couple of hours, and strangely this one does not have any glitches either. Neither normal or high-speed mode seem to make any difference. So I am not able to produce any glitch problems. Perhaps it is my TM-8 transmitter module that makes the difference? But reading the Fr-Sky TRF8 manual it states that you must turn of sail-safe in the Futaba radio and use the internal receiver FS instead. Otherwise you get throttle glitches.

    @Marco, can you say if the Futaba F/S was on or off on your radio?

    RC Groups - View Single Post - OrangeRx Futaba FASST Compatible 8Ch 2.4Ghz Receiver gets hot?
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  • T3

    I assume this is all for 2.4GHz Futaba radios and doesn't affect any of the older 72MHz stuff right? I just ask because I use a 9C for FPV work and will be installing the APM 2.5+ in a plane and tricopter. From what I gathered, it's likely only a newer 2.4GHz issue but it would be good to know if I really need to care about this.

    I used Spektrum for any of my 2.4GHz stuff so at least that shouldn't be affected.

  • Moderator

    Based on what I've been able to find on Futaba's website I would suspect that the following receivers when used with the compatible transmitters (most but perhaps not all of which are listed following the list of receivers) outputting in either MULT or MLT2 modes will experience the same issue with the PPM encoder on the APM 2.5.

    Receivers: R608FS, R6008HS, R6014FS, R6014HS, R6108SB, R6208SB, R6203SB, R6203SBE, R6202SBW, R6303SB, R6303SBE

    Transmitters: T8FG, T8FG SUPER, T10C, T10CG, TM14, T18MZ, T14SG

    If you have one of these Receivers/Transmitters and can cofirm or add to this list that would be great!

    I can confirm that the R6208SB that ships with the T8FG Super does in fact have an issue with ArduPPM firmware before 2.3.13.


    Nathaniel ~KD2DEY

  • With the Usb connector on my APM2  trashed  I will have to pull the board and solder the isp header to update the PPM encoder. 

    Are all Futaba radios  seeing the glitches?  The discussion had reference to some receivers  not displaying the problem. My FS617 receiver   in 7Ch mode  did not  have  motor  log spikes last  time I looked at the logs.  Does it just happen when CH 6 or 7 are used ?

  • Developer
    There's an interesting discussion here about Futaba it would appear yes you do need too, but check the details.
  • Moderator

    Sorry if this is hard to read, I was having all sorts of format issues while typing! The text was italicized when I didn't want it to be, the font changed when I didn't change it, and the word wrap stopped working! Ah well I guess you'll get the point anyway.


    Nathaniel ~KD2DEY

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