[FC] Scisky & DSMX Satellite Mod

Spoiler: I added a LemonRX DSMX sat to the scisky - but I’m not yet 100% happy.

I received a scisky today and after trying to bind it for a while I noticed that my transmitter does only (thanks to some EU regulations) support DSMX but not DSM2. There are various versions of the DX6i - mine is unfortunately DSMX only.

I planned adding a different receiver module to the scisky beforehand - now I’m left with no other choice. I strongly recommend not to try this, it involves cutting a little trace on the board - nevertheless the changes are reversible if you are careful and know what you are doing.

Tools (if you lack any of the first four, please don’t even try):

  • proper soldering equipment
  • desoldering braid (I used a 1,5mm type)
  • flux
  • a sharp knife
  • something to clean flux residues (if your flux leaves some)
  • magnifying glass (recommended - for inspection)
  • other random tools like third hand, multimeter etc.
  • a prebound (!!!) LemonRX DSMX satellite

You only need RX & V+ & GND to connect your sat to the scisky.
GND is really easy and V+ should be 3.3V for a spektrum satellite - the following two pads do the job (please excuse the picture quality, no better camera available):

Last but not least you need to find RX and disconnect it from the onboard receiver.

Remove any solder from the three pads. Cut the very tiny trace between the right and the middle pad - make sure these pads are disconnected. Cutting this trace defuses the onboard receiver (it will still flash like crazy) - you can revert this step by adding a little bit of solder to reconnecting the two pads. Last step: Solder your RX wire to the rightmost of the three pads. Done.

The software configuration part is left as an exercise for the interested reader :smiley:

Problems with this approach:

  • No binding possible without additional equipment
  • The onboard receiver still flashes around - if you have a reversible way to cut the power from that part of the board, please let me know (removing the LED does not count ;)).
  • The position of the pads I used is far from optimal - I only wanted to have a working prototype

The soldering isn’t too beautiful, please ignore that - its only for testing and will not be permanent.

EDIT:
Binding is of course possible via CLI from cleanflight - I just didn’t know the procedure to do this from CLI back then.

2 Likes

Well done! I find it strange that Spektrum moved to DSMX only. Dsm2 is a great protocol. Bad move by Spektrum.

The move to dsmx only is not Spektrums fault I think.
It has to to with stupid EU legislation. Due to this since January 2015 it’s only allowed to to sell dsmx transmitters.
You’re still allowed to use dsm2 you already have.

Ok, but there are also dx6i transmitters which are sold before 2015 and only support dsmx. In this case Spektrum is to blame.

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As mentioned before, not entirely Spektrums fault and I could have been a bit more careful when choosing my transmitter. I wanted to try to add an satellite receiver to the scisky anyways - not knowing that I will have to do it (that certainly sped up the process).
I’m usually not happy with the range of the onboard things. Would have liked to try how well the onboard scisky receiver performs, but I didn’t have any trouble with the LemonRX receivers yet (and I have a couple of those around).

Awesome job! When you have a minute could you maybe post a better picture of the signal soldering point, and the trace to cut?
And maybe you found an other (even irreversible) way to disconnect power from the Rx part of the board? Thanks for your work man

Thank you. Currently my scisky is gathering some dust, too many other projects to work on. :wink:

If you use some flux & desoldering braid on the 3 pads you should be able to see the “micro trace” between the center and right pads (orientation as in the picture with the yellow wire).
Simply solder signal to the right pad (it’s NOT soldered to the yellow tantalum cap sitting right to it) after cutting the trace between the center and right pads.
I think you could also use a JST SH 4 pin connector and grab RX from the serial port - you still would need to cut the trace. Didn’t look for more elegant ways to disable the onboard receiver yet.

Since I had the SciSky already on the table, I thought I should clean up the DSMX sat mod a bit with a custom cable (ignore the stuff hanging around close to the USB port, that’s the serial port mod ;)):

If you have a cable like that you only need to solder to one pad (V+, 3.3V) and break the trace on the bottom side of the board as described in my previous posts.

3 Likes

Hi all ,
i’ ve tried to use an orange r616xn ppm receiver instead of a lemon satellite .
It bind ok, on cleanflight gyro and accelerometer is ok but receiver tab is not working,
I use a spektrum dx6i. i checked the cut of “micro trace” between the center and right pads.
I soldered dirctly the wire because i no have a JST SH 4 pin connector.
Somone can help me, giveing some suggestion of thinks to try ?
Receiver with a naze32 fc it works pretty good.
Sorry for my poor english
Maurizio

Unfortunately, I don’t think that PPM is going to work. Maybe that’s what the third magic pad is for?
You need a serial satellite receiver if you want to use that hack.
From HobbyKing:

Nevertheless, that receiver looks very cute and might be very useful for other FCs which support PPM (I think the mulftiFlite FC should support it) - you would have two free UART ports with that receiver.
I only have Lemon RX Sats (Standard DSMX Sat, Diversity DSMX Sat) here, they are quite affordable.

Edit: I think this Orange R111XN should also work.

Thanks for advice, i have already ordered one serial dsmx satellite from lemon. I keep the orange for another FCs project:smile:

If you have to get rid of it… cough - I have some of the lemon diversity receivers… :wink:

I have to thank you for your post, because that’s exactly the type of satellite I could use for another build which requires two UARTs - but unfortunately the R616XN out of stock on HK.

I keep it, thank for advise anyway.
this Orange R111XN do you think also is serial rx ?

Not exactly sure, but I think so - If I recall correctly the original Spektrum sats talk via serial with the main receiver and HK states that their nano sat is compatible with some of the original Spektrum equipment - therefore that should be a proper serial rx.

I’m going to order one it looks pretty and small, as soon as arrive it i’ll contact you.
You have been very helpfull for me. Thank you
:slightly_smiling:

Hi, here i am with dsmx satellite wired to the scisky, but no way to bind with my Dx6i receiver, where i am wrong ?
I cut the tiny trace between the right and the middle pad. Cheked the soldering. The red light on satellite when i plug the battery blink only twice and the nothing.
Any advice ?
Thank you

So I’m not the brightest here, but can you use the CLI to issue the bind command in Cleanflight?

Can you pre-bind the satellite with some other receiver? I never really tried to get the satellite into bind mode from the SciSky. I thought it was not possible because the SciSky has no bind switch - but that’s not really true, there is a CLI procedure which can trigger the bind mode without bind switch (I didn’t know about that procedure when I started this topic. I left the RC hobby over a decade ago - now everything is different ;)).

It should work using set spektrum_sat_bind = 9, I’ll try that later. Same satellite, also DX6i. Plus, I’ll check whether your wiring is correct later - I hate the new “all black” cables from LemonRX.

Remember LAS? in FM frequence quartz vibration ,ohhh nice time :wink:
haha now all bind :smile: