Futaba S.Bus for R7008SB receiver

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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Fri Jul 12, 2013 2:44 am

Happy to report that first actually flights worked without any problem. I made sure to run down a battery to hear the alarm via telemetry 8-)

Rusty
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Re: Futaba S.Bus for R7008SB receiver

Postby Kisssys » Fri Jul 12, 2013 12:35 pm

Hi Rusty,

Have you tested what happens when you turn off your transmitter and the sbus goes to failsafe?

In the logs does the radio quality change with the TX off?
Steve
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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Fri Jul 12, 2013 3:55 pm

Hi Steve,

I did try turning off the radio, and I was very surprised to see the signal quality to go zero. The radio is set to hold the channels if it loses the link, systems usually don't recognize this as a loss of the radio link. The s.bus protocol has a failsafe flag, and I'm assuming (for now) that the software is checking that flag. It's definitely something I'll look into more, because I've always ignored failsafe settings in the software, since I never thought they'd get used.

BTW, how does that radio quality value get computed? There's no RSSI, so does it count dropped frames somehow?

Rusty
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Re: Futaba S.Bus for R7008SB receiver

Postby Kisssys » Fri Jul 12, 2013 4:15 pm

In spektrum it just counts dropped frames, when I tested the FrSky receiver with JR TX and sbus out it would not recognize the fact the receiver was in failsafe.

I'm not sure what they are doing in futaba, but I assume they check for the flag.

That all sounds good.
Steve
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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Fri Jul 12, 2013 5:39 pm

I just looked at the decode routine in futaba.c, and it doesn't appear that the flags are decoded. I'm not really a code, guy, so it might just be done somewhere else that I'm not seeing. The R7003SB should be here today, so I'll look into it more when I'm testing that RX.

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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Thu Jul 18, 2013 2:07 am

Greetings,

The R7003SB I received last Friday was DOA, and wouldn't power up, so I had to wait until today to receive another one. I did the captures, but haven't really analyzed them. I did test the R7003SB receiver with one of my copters using the modified code, and it works fine in 12 and 18 channel mode. I'll update the pdf document once I finish analyzing the output of the R7003SB receiver, but I think the modification to the code that Bill suggested is a winner.

Thanks,
Rusty
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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Fri Jul 19, 2013 2:23 pm

OK, I finished testing the R7003SB receiver, and I'm happy (and surprised) to report that it works just like the older s.bus receivers. In other words, the s.bus output from the R7003SB will work with the previous s.bus code. That's great news, since the R7003SB is smaller, cheaper, and will do almost anything the larger R7008SB will do. The only limit is the number of PWM channels that are available directly from the receiver, but that won't be an issue for most people. The R7003SB came out around April 2013 I think, so I think we all just assumed it wouldn't work.

The R7008SB seems to be the only receiver that won't work with the old s.bus code, but I guess we'll have to be suspicious of any future receiver models as well.

Attached is the final pdf report for my s.bus analysis.

Cheers,
Rusty
Attachments
sbus.pdf
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Re: Futaba S.Bus for R7008SB receiver

Postby bn999 » Fri Jul 19, 2013 2:37 pm

Trunk code updated
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Re: Futaba S.Bus for R7008SB receiver

Postby 13brv3 » Fri Jul 19, 2013 3:32 pm

Thank you Bill!
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Re: Futaba S.Bus for R7008SB receiver

Postby Kisssys » Fri Jul 19, 2013 5:10 pm

Rusty,

I would recommend that you look at the Quality thread and do the small code change. It seems to have solved the quality problem which was present on all radio types.

Cheers
Steve
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