Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

erskyTx runs on many radios and upgrade boards
ersky9x was a port of er9x for use on the sky9x board.
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jhsa
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Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Sun Nov 13, 2016 1:03 pm

Let me start by thanking Mike and Midelic for making this possible.
Midelic developed the DIY FrSky D8 compatible receivers

https://www.rcgroups.com/forums/show....php?t=2124647

For this project I used a little receiver based on the ATtiny85 microcontroller and on a low power CC2500 RF module. it can be found on ebay.. For example:

http://www.ebay.com/itm/2pcs-CC2500-2-4 ... SwOyJX4zt2

I do not recommend a seller called "e-zealot" as I have never received my modules. :(
Good that I have bought from different sellers, or I would have been stuck..

Here is a video of it working on my 9XT radio:

https://www.youtube.com/watch?v=LEOPeAipBx4

The receiver outputs 8 channels SBUS and it connects internally to the trainer port. In this case it is soldered to the backboard of the radio, to a solder pad that connects to the tip of the trainer Jack plug. (See picture below).
Both 9xtreme and Ar9x boards have 5V available on pin headers (Expansion grid on the 9XT). So I used this voltage. I think that if you use a 2 cell LiPo battery or 6 NiMh cells, you could also power it from battery voltage. I would avoid connecting to 3 cell LiPo batteries, even if the LP2985 regulator is rated at 16V. And it is a waste of energy anyway :)
But if you must use a 3 cell LiPo or LiFe, then I would recommend placing a 5V regulator before the LP2985 3.3V regulator.
Connection on Backplate.jpg
It is still possible to use another radio connected with a trainer cable as before, as it should override the receiver due to the resistor on the receiver's SBUS signal output.
I also think this little RX might have some advantages over the bluetooth, such as better range and less interference on the main RF signal. The bluetooth receives and transmits, causing sometimes problems to the telemetry reception. This rx only receives (obviously ;) ), so it should not interfere, and it should also use less current from the radio's battery.
At the moment, Mike is still in the process of implementing this in Ersky9x, so the options to use this are only in the debug menus of the latest test versions of ErSky9x, and the settings are still not saved. That means, you have to configure the settings every time after you reboot the radio.
Link to the latest test versions of Ersky9x:

viewtopic.php?f=7&t=4676

Currently i have this working on my 9xtreme radio as well as the Ar9x TX.
I'm using slightly different circuitry for each of them on the receiver's SBUS output. Here are the schematics for both setups.
First the Ar9x, 9XR-PRO, skyboard.
DIY Frsky RX ATtiny85 SBUS Trainer.jpg
And the 9xtreme. Note the different resistor value on the SBUS output. Also I think the diode might not be needed there, but I didn't test without it.. It works with it in there, so I have left it.. When I open the radio again, I will test without it and change the schematic accordingly.
DIY Frsky RX ATtiny85 SBUS Trainer_9XT.jpg
The zip file includes PDF files for etching the double sided PCB. One for the top side and another for the bottom side. Every side has 4 boards, just in case a couple might not come out good. It can happen As I make my own PCBs at home, I have placed a few square vias around the board, and I use them to line up both top and bottom sides. For that, I drill some 0.8mm holes through the vias around the board using a printing of the bottom side as template. These will be used to line up both top and bottom printings when ironing them to the copper board. I use the laser printer method.
When ironing the Bottom and top sides printed on Photo Paper, I first iron the Bottom side that has more covered surface and thicker tracks, after I lined it up using the previous drilled 0.8mm holes, and some needles. Then I do the same with the top, using the same method.
Please note that the spacing between the RF module board's pins is only 1.2mm, that means, both sides will have to be very well lined up, and the drilling completely vertical..
PCB.zip
(79.31 KiB) Downloaded 57 times


Here are some pictures of my installation on the Ar9x radio.
IMG_20161112_145706.jpg
IMG_20161112_145633.jpg
IMG_20161112_214754.jpg
IMG_20161113_024832.jpg
IMG_20161112_214904.jpg
IMG_20161112_214717.jpg
Programming the ATtiny85:

You will need a ISP programmer, like the "UsbAsp". I used an "mysmartUSB Light"

WARNING - YOUR PROGRAMMER MUST BE CAPABLE OF 3.3v LOGIC LEVEL.
5V LOGIC LEVEL WILL PROBABLY DESTROY THE CC2500 RF MODULE.


Here is how to connect the ISP programmer to the board.
Programmer Connections.jpg
Read the chip's signature and/or the fuses before attempting to write anything to it. It is a good way of finding out any problems. If reading fails, find the problem and fix it. Maybe something not connected to the right place, or a bad connection somewhere.

If read is successful, then proceed to program the following fuses.

low_fuses=0xE2
high_fuses=0xD7
extended_fuses=0xFF


After programming the fuses, proceed to write the firmware.
FrskyRx_Attiny85_SBUS_NOPULSE_4_DJTFIX.zip
(6.23 KiB) Downloaded 67 times
Midelic wrote this version specifically for this trainer setup. When link is lost, the receiver will stop all pulses. This allows the teacher transmitter to detect it and take control of the model immediately.

How to bind the receiver to another TX with a frsky DHT or DJT module. It might also work with the XJT in D8 mode but I don't have one to test.

Turn the teacher TX (has this RX installed) ON while holding the RX binding button. The Trainer RX will enter Bind mode
LED will flash very fast.

Now turn ON the student's radio while holding the bind button on the RF module (DJT/DHT). The receiver should now bind and the LED should start flashing slower,about twice a second. Bind is still not complete. Procced to next step.

Leave the radio with the receiver ON, but turn the student transmitter OFF, and then ON again. Clear all alarms, if any. LED will blink even slower, about once a second. bind is complete. This normally is to set the failsafe. We do not use this setting as the RX doesn't output any pulses if the RF link is lost. But it is necessary to do it anyway to complete binding the rx..

Reboot the teacher TX (with the receiver) and the LED should now stay ON. That means it is connected to the student TX.

How to configure a trainer setup using the SBUS signal from the receiver.

Now that you have bound the student (SLAVE) TX to the MASTER radio, let's configure the trainer setup on the MASTER TX.

Please make sure the student radio is bound to the receiver you've just installed in your radio, and is sending its 4 sticks's positions on the first 4 channels (CH1 to 4). If the student (SLAVE) radio runs Ersky9x/Er9x or even OpenTX, the mixer should look similar to the picture below.

Trainer Over SBUS Setup_1.png
Trainer Over SBUS Setup_1.png (1.04 KiB) Viewed 3262 times

You will need at least the latest Ersky9x test version from today (06-Mar-2017) installed on your MASTER radio, to be able to set the trainer as explained in the video below.

https://www.youtube.com/watch?v=vOfPuUvTLh4

Enjoy, and don't forget to share your build with us :) ;)

João

EDIT: If you can't build your own receiver you could probably use an original "X" series Frsky receiver for the trainer over SBUS setup. In this case, just make a cable to connect your RX to the trainer port using a 3.5mm jack plug. You will have to power the receiver externally of course. As far as I know, none of the original D series Frsky receivers can output SBUS.
Alternatively, you could also use one of those Frsky compatible receivers sold by banggood, but make sure it can output SBUS, and that it stops pulses when link is lost.

I don't own any X series equipment and also any commercial compatible receivers, so I can't test it or give any advice.
I think Mike did test this with an original receiver when he was implementing this though.
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW


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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Sun Nov 13, 2016 3:42 pm

First post updated with firmware and some instructions..
Midelic, thank you for allowing me to post your firmware file here..

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Thu Nov 17, 2016 5:22 pm

Yesterday, 3 more of those little modules arrived. That means SBUS trainer receivers for all my radios supporting ErSky9x. :D

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Thu Jan 05, 2017 10:56 pm

If someone builds this, please let us know how it works for you.. It works great here. :) Just need good weather to test it at the field. Then maybe Mike would do a more permanent implementation of this great feature in ErSky9x. :) ;)

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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Romushock
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by Romushock » Sun Mar 05, 2017 9:41 pm

Double post, sorry...
Last edited by Romushock on Sun Mar 05, 2017 9:45 pm, edited 1 time in total.


Romushock
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by Romushock » Sun Mar 05, 2017 9:43 pm

Hi Joao,
Can you share here a BOM and board print img (for AR9x, without zener diode)?
Thanks.

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Sun Mar 05, 2017 10:32 pm

It is the same. Just bridge the zener diode's pads together. The list of the components you have to buy is in the schematic.
I don't have specific shops's links as in your country you have other shops :)

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Sun Mar 05, 2017 10:41 pm

Ok, I see that when I started the thread I this wasn't still fully implemented in Ersky9x.. Now, at least in the latest test versions it seems to be (Thanks Mike). So, I will upload a board layout. Don't expect nothing professional. It is the layout I used for etching my own boards. It's quite late now so i will do it tomorrow. Please remind me if I forget ;) :)

João
My er9x/Ersky9x/eepskye Video Tutorials
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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Mon Mar 06, 2017 2:14 pm

First post updated with a zip file including some pdf files you can use to make the board..

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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Romushock
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by Romushock » Mon Mar 06, 2017 2:40 pm

Great, thanks man. BTW did you notice any kind of interferences when use 4in1 CC2500 and your rx in the same time?

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Mon Mar 06, 2017 2:54 pm

No, I haven't, and there shouldn't be any because this is just a non telemetry receiver.. So, it does not transmit anything.

João
My er9x/Ersky9x/eepskye Video Tutorials
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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Mon Mar 06, 2017 4:08 pm

First post updated with a explanation (in video) how to setup the trainer using this SBUS receiver in Ersky9x

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by pierrotm777 » Thu Jun 29, 2017 12:29 pm

Thanks for this share .
Can you say me if this module work also with a PPM signal ?

Thanks

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jhsa
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Re: Trainer Setup Using a DIY Frsky Receiver Outputting SBUS

Post by jhsa » Thu Jun 29, 2017 1:19 pm

You would have to flash it with some code that outputs PPM.. That exists (I think) on the project forum that I have linked on the first post..
But why do you need PPM instead of SBUS? Which radio do you want to use this with?

João
My er9x/Ersky9x/eepskye Video Tutorials
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