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
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
APM 2.x ArduPPM Firmware v2.3.13 (recommended update for Futaba radio users)
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
have 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?
Have you seen any receivers other than Futaba receivers with 8 or more channels being susceptible to this problem? Also do you see any reason not to update to this PPM encoder firmware revision if your not sure if your receiver is affected?
Latest generation Futaba receivers like the R6208SB is the only confirmed one with problem.
If you bench test for an hour or so and see no spikes in the GCS, it should be fine.
If you want to be absolutely sure, I recommend using a receiver with PPM output. Using PPM-passthrough there should not be a spike problem regardless of receiver brand or ArduPPM firmware revision. For this I would recommend this Futaba FASST compatible receiver. http://www.hobbyking.com/hobbyking/store/__19626__FrSky_TFR4_4ch_2_...
Yeah that's the standard receiver that ships with the Futaba T8FG Super 14 channel system. Personally I haven't noticed a problem yet, but I don't expect it would be as obvious in a fixed wing system. I'll be updating the encoder just to be sure.
In my opinion unfortunately there is not a rule, may depend on the rx firmware, Orange Futaba and FR-Sky TFR8 (is the same rx) cause these problems here, tested with APM2/2.5 in different setup.
For this reason owners of Futaba update you encoder whatever, with the new one the problem is completely gone here.
I agree that the list shown in this post isn't complete, and may not be considered accurate until people add confirmed receivers to the list. I disagree however that there isn't a 'rule'. In my opinion this problem seems to affect any Futaba compatible receiver working in either MULT or MLT2 mode which makes the capable of reading a signal containing more than 7 channels. I thinks that all S-Bus compatible receivers and any native 8 channel Futaba compatible receiver. However until we start to see a list of confirmed receivers and the Transmission mode they are being used with it's only an opinion.
A glitch does not automatically make it a problem with the PPM encoder. It might just as well be a bad connector or electronic interference related problems. It might even be a bug in the radio system. Certain OrangeRX/FrSKy FASST receivers for example has a problem with throttle glitches because of compatibility problems with the Futaba radio fail-safe system.
So I what I am trying to say is that "I had a glitch using receiver xxx, fix it" does not really help. If we are not able to reproduce the problem, it can be close to impossible to fix at times. Simply because we might not even know what we are trying to fix.
At current the MULT channel grouping is the only thing that makes sense technically. And confirmed reports of fixing the glitch problem by improving the interrupt system response time, further validates that view.
I used to get twitches on my Tricopter firmware 2.6 using a Futaba 10c fitted with Frsky module
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 ?
What are the exact symptoms of this issue? Just looking to see if there are other known side effects or obvious implied effects that may make it more urgent to apply the update. Can this trigger odd failsafe related issues on certain ArduPPM /Ardupilot Software combos or does it simply cause "glitchy motors"? I tried to catch up via the forums obviously but it was unclear.