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droneprojetsn2 / ardupilot-mega

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ppm encoder does not read the radio input from the receiver quite well #684

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago 
What steps will reproduce the problem?
1.connect the receiver with APM or APM2, and power on.
2.Use the MissionPlanner's FlightData to watch the radio input from the 
receiver.
3.We only need to watch the ch1in and ch2in. Use the trim button on the 
transmitter to slightly adjust the value of ch1in and ch2in.

What is the expected output? What do you see instead?
The ch1in and ch2in should follow the trim button of the transmitter 
accordingly.
But, the problem I see is like this: When the values of ch1in and ch2in are 
close to each other, for example, when the stick is in the middle position, and 
the trim values for channel 1 and channel 2 are
close to each other, the application of trim button of chinnel 1 will 
not only trim the value of ch1in, but also influence the value of ch2in to some 
extent. And vice versa.

What version of the product are you using? On what operating system?
I found this problem both on APM1 and APM2.
All the versions of firmware give the same problem.
My operating system is win7.              

Please provide any additional information below.
I use a Futaba T10C 2.4G transmitter and different receivers.
The Futaba R6014HS(14 channel), 6208SB(8channel), and 6008SB(8channel) 
receivers all give the above problem. But R617FS (7channel) receiver does not 
have the above problem. So I guess all receivers with 8 or more than 8 channels 
will all give the above problem.

I believe the problem is the firmware of the PPM encoder, i.e. the firmware of 
AT328 on APM1 or AT32U2 on APM2. I believe the ppm encoder does not read the 
input from the receivers quite well. I don't know exactly what is the 
difference between the signal from a 7channel receiver and a 8+ channel 
receiver, maybe it is the signal timing between the channels.

Original issue reported on code.google.com by tststs2...@sina.com on 18 Jul 2012 at 2:42

GoogleCodeExporter commented 8 years ago 
I have tried a seires of receivers. 
Futaba R6014fs receiver and R6208sb receiver have a PWM interval of 14 
microsecond. They are too fast, so have the above problem.

Futaba R617fs receiver has a pwm interval of 17 microsecond. FrSky TRF6 
receiver has a pwm interval of 22microsecond. So they are slow enough, and 
don't have the above problem.

Does this mean the 32U2 chip is not fast enough to resolve the fast PWM signal? 
Or the firmware updating can fix this?

Original comment by tststs2...@sina.com on 20 Jul 2012 at 10:40

GoogleCodeExporter commented 8 years ago 
Has this been addressed or solved in any way. I was planing to use R6208SB 
received (comes with Futaba T8FG Tx) on APM2.6 and now I am puzzled if I should 
get another receiver?

Original comment by Bortek...@gmail.com on 3 Jan 2014 at 6:53