I’m using a Pixhawk with 4.0.5 and a Frsky R-XSR, OpenTX 2.3.10. I’m trying now for several hours, no luck. I’m using an inverter between S.Port and TX/RX. Tried Telemtry 1 and 2 ports, both are working with standard Mavlink modem. Disabled RTS/CTS, protocol set to FrSky Passthrough, SERIALx_OPTIONS is 4 (Half-Duplex).
What is working:
I can see the telemtry from the receiver
The inverter is also working, first channel is receiver output, second channel RX input on PixHawk, the receiver sends data to the PixHawk:
However the Pixhawk TX does nothing, it is high (second channel):
Any idea how to debug this? Why is the Pixhawk not sending any data?
I was fixed this problem on my QX7 with this configuration
SERIALx_OPTIONS = 0 (if using convertor like rs232)
SERIALx_Protocol = 10
Wiring like this post
If telemetry is not working till this step try to add 2 1n4007 diode before Vcc from fc to converter
Thank you very much, SERIALx_OPTIONS set to 0 did it
Never tried without 4 (half-Duplex) because it sounded logical and in
" In general, F4 based autopilots using an external bi-directional inverter can use any UART with the following configuration:
SERIALx_OPTIONS =160 (enable pull-up/pull-downs on TX and RX pins for those external inverter circuits that may require it)
It good to hear that you got it working
Yes a little bit confusing but its for other flight controllers like omnibus f4 not pixhawk
Your right, I think that came from me trying it first with a Mamba F405 and then moving on to the Pixhawk. If I’ve finished the second inverter I try it on the F405 again.
Hi, I also have a similar configuration and the same problem, even putting 0 on serial option unfortunately I have not solved. Omnibus nano F4 v6.0 and radiomaster
Here are the tests I did, can I try anything else? Thanks
I bought a couple of these max3232 cheap china boards from ebay and the first one has worked for about a year and does not get hot, never tried the second one till this week. It was not working, so I put a scope on it and found some of the through holes on the board (where you connect the wires to on the end of the board) were not making contact. I had soldered the two diodes to the bottom this time and the wires to the top.
And the diode that is connected to the S.Port was open (because of the…
The MAX323 boards have two circuits, one on each side of the board. Make sure all your wires are using the same side.
did you tried this ?
Problem solved by adding 2 1n4007 diode before VCC from FC to RS232
Not yet. This is my inverter:
This is my inverter. green tx to tx1 FC , grey rx not connect, red Vcc to FC. violet GND to FC, yellow to S.port RX, black to gnd RX
Why 2 diode 1n4007? Thanks.
Some rs232 converters are not working with 5.2v
2 1n4007 will drop voltage to 3.2 to 4 volt and its will work
but if i have a 3.3V pad on FC (omnibus nano), can i try with this? Without diodes? My quad is micro only 3"
If you have 3.3v ignore this step
Now my inverter it’s connect to 5Vcc on FC pad. Can i try to connect to 3.3 pad?
Hi, don’t worked at 3.3V. I tryed protocol 4,10,23. Serial option 0,160. Baud rate 115,57. No new sensors on radiomaster.
i dint used radiomaster, is it OpenTx ?
Yes, open TX.
I connect only pad TX1 on TX pad inverter, could that be a problem?
If your FC is based on a F4, you need both TX and RX connected.
Also, you need a diode between the inverted Tx-out and RX-out, where your S-Port wire goes to the receiver.
Have a look here, maybe it help you.
FrSky passthrough and Yaapu works fine (Copter 4.0.5 Stable)
Frsky Smartport Telemetry,
I use receiver X8R and Smart Port Connected Ground and Signal to Inverter (no 5v red cable)
Then from Inverter to TX4,RX4,5V&G on the F405-STD
SERIAL2_OPTIONS 0 (Its several options available now)
[Max3232_3.3v_diode] [F405-STD Yaapu working, 5v from FC only][No 5V from receiver]
I ended up creating a new inverter with cabling to suit the pins on F405-STD.