ah, what uart and what serial port number are you using, the F405-STD numbering does not match the silkscreen
4 or 5 or 3
more I saw in the link referring to it what was the corresponding
Hello everbody,
I hope i can find some help here. Iām trying to get the telemetry passthrough working on a Beaglebone Blue with arducopter and yaapu script. I tried several Max3232 and now i ordered the Frsky FUL-1 TTL RS232 Converter.
Itās connected like here http://ardupilot.org/copter/_images/Telemetry_FrSky_Pixhawk-SPORT.jpg
It seams to works the script is getting data but the Messages seem to be mixed.
I trying to get this work for a few months now, perhaps anybody knows whats wrong here.
Thanks Christian
Hi Christian,
Iām afraid youāre having polling timing issues. A Linux based board might have a slight delay in the serial telemetry IO thread that prevents all packets to be sent when asked to by the rx polling packet.
I donāt think swapping cable will make any difference.
You might try with @Eric_Stockenstrom mavlinkToPassthru firmware, mavlink traffic is very well supported under linux.
This is exactly what I was wondering, since I have seen the Oscar Liang post and I have an R-XSR that I can do the soldering to the un-inverted Smart Port. Has anyone got this to work successfully? I am trying to get this to work with a Matek F405 Wing, by the way.
Worked for me; miniConvergence with mRo X2.1 FC
to use frsky r-xsr do i have to use any special settings?
this is the signal I have will be able to use an Arduino to encode this signal in F405-STD
this signal after max3232 would this be the inverted one?
what oscope hardware and program are you using. I need a scope for serial coms like s.port.
Is there any way to test Frsky passthru without an oscope? Iāve built 5 MAX232 inverters and none work. GPS is never discovered on my X7. This is using a Mateksys F405-Wing. I copied the wiring exactly, and tried 5 out of the 10 MAX232 boards I bought. Iāve tried every serial port except 2 (SBUS) and 0. I built a couple of 3.3v versions using a diode, then a resistor bridge to drop the voltage, and also connected to the 3.3V pins on the FC. I canāt think of anything else to try short of seeing the signal values on the port.
I bought the converter nothing else yet to work on matek f405 std
this one is found somewhere for a better price maybe a cheaper one is also enough
what i think this f405-std card is not compatible i bought it for being small and i canāt use it because of that
Hi David,
Thereās no easy way to test passthru, you need a logic analizer or an oscilloscope 
I have at least 3 batches of 10 max3232 that do not work, I bough them from ebay, banggood and aliexpress.
What I ended up doing is buying genuine TI ICs and solder them in place of the fake ones, still way cheaper than buying a ready made working cable.
I used the circuit from this pdf. Itās in German but easy to follow. The converters made from this work perfectly on my Matek-F405 Wing and on my Pixhawk2. I already had all the parts on-hand too. I bought a collection of general purpose resistors, one of transistors, and one of capacitors just for fun, and they have really been helpful for simple DIY circuits. You can use 2N3904 transistors for this, but note the pinout is reversed from the BC547. The collector and emitter are swapped.
Just as a kind reminder when using with APM Plane: this is from the release notes page on github:
Release 4.0.3beta1, 10th January 2020
[ā¦]
The most important fix is for FrSky pass-through telemetry. Pass
through telemetry support had a race condition which could lead to the
flight controller generating a fault and rebooting. Until you are
running a firmware with the fix you should disable FrSky pass-through
telemetry by changing SERIALn_PROTOCOL from 10 to 0 on the where you
have SPort enabled.
Happy flying!
Thought I would update this thread too, for the CUAV V5 Nano I was able to use a very basic 2-wire cable with just a pull-down resistor between the two wires, no other electronics required.
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Digging up this thread. I have been trying to make my own telemetry cable as per instructions in this thread. I cannot get it to work 
My board is based on MAX3232. I have checked my soldering, I have tried to swap TX and RX cables on the TTL side, checked cables and connectors. Everything seems to be fine. One funny thing you may notice is the LED diode which I put in because I donāt have a normal one handy. The functionality should be the same though and I actually do see it briefly flash which may be a good sign that something is happening.
I installed Yappu script on my Taranis and no matter what I do, no telemetry is showing. Any idea where to troubleshoot?
P.S. - I didnāt put in any pull up resistor, the board is not getting warm or hot.
Hi Alex, i have a quick question, how crossfire telemetry would work with this script?
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Nope, only frsky sport/fport.
thanks man for the quick response, iām just trying to figure out to show data on my telemetry screen such as GPS cordinates etc