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#1 2016-01-29 19:24:23

geams13
Member
Registered: 2016-01-29
Posts: 3

RX31c Firmware

I recently ordered four RX31c (K1)  from your website and I'm having some problems with them.  The instructions that come with them says they are running software version 351-2.

First, when I bind a transmitter to them, they appear to be in in DSMX mode and not DSM2.  Is there a way to revert to DSM2? 

Second, the serial protocol described on the link from your website appears to be outdated.  Looking at the binary stream, it appears as though the checksum no longer includes summing Byte 2 (signal quality).

And finally, the receiver appears to run fine for a minute or two (solid LED), but then it seems to timeout and the LED blinks quickly.  There is no online documentation for the version of firmware installed. Can you point me to accurate documentation?

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#2 2016-01-29 20:33:45

DavidT
Member
From: UK
Registered: 2015-10-18
Posts: 6

Re: RX31c Firmware

Hello, I make this receiver. It will bind to DSMX if the Tx allows this. If the Tx has a setting to force DSM2 then it will use that. Look under Frame Rate on Spektrum Tx's.

I believe serial checksum does include byte2 but please post all your bytes or email them to me.

I think the led blinking means it is missing some frames. It's not normally a problem as there are two transmission every 22ms but it does mean my timing in the Rx does not cater for all scenarios. I have made a note to look at it.

I have been too busy to create a web page for the latest version. Sorry. There's not much different although the pad channel order has changed. This is should be correct on the packaging supplied.
Regards, David.

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#3 2016-02-03 22:05:05

geams13
Member
Registered: 2016-01-29
Posts: 3

Re: RX31c Firmware

Thank you for the quick reply.  I'm sorry, but I didn't realize you had posted a response.

I forced the Spektrum transmitter into DSM2 mode and was able to bind it that way.  Thank you for that info.  It appears that I'm not getting the "missing frame" error using the DSM2 mode.  I'm not very knowledgeable about RC transmission protocols, so I have no idea if this makes sense or not, but the problem seems to resolved for me in that mode.

Below are the bytes I'm reading from the serial stream.  I'm fairly confident that the checksum is summing only bytes 3-16.  I've updated my parser to handle both cases, but this is obviously not the optimal solution.

Throttle at Zero Bytes:
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00
39 9F 00 87 05 FD 0A 00 0E 00 13 55 16 00 1A 00

Full Throttle Bytes:
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0B 9F 03 55 05 FC 0A 01 0E 01 13 55 16 00 1A 00
0B 9F 03 55 05 FC 0A 01 0E 01 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00
0A 9F 03 55 05 FC 0A 01 0E 00 13 55 16 00 1A 00

Thanks again for the quick reply.

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#4 2016-02-06 08:34:23

DavidT
Member
From: UK
Registered: 2015-10-18
Posts: 6

Re: RX31c Firmware

Thanks. You are correct. The program has a bug. I start the checksum with rssi but then zero it before adding the other bytes in a loop. Thanks for letting me know.
Regards, David.

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