SP Racing F3 (Clone) and D4R-II Telemetry connection

[moraitis_george]

Hello guys.
I have a noob question here. I am sorry if it has already covered. I see similar setups but with different controllers which makes me wondering how in my case, things will work.
In my firts rig, I have a D4R-II, PPM connected where I never tried to connect the telemetry which I want to try now. I have a clue that I should connect the side port of D4R-II (maybe 4th pin), but I don't know where. My connection scheme between SP Racing F3 (Clone) and D4R-II is below. Do you have any suggestion on this?

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[ched]

OK so I am not familiar with frsky but looking at a few diagrams it appears pin 3 is Tx and pin 4 is Rx. So they should be connected to a spare uart. Wiring should be crossed so receiver Tx to FC Rx and receiver Rx to FC TX. I have no idea what telemetry setting should be on the fc. Hope that helps?

[moraitis_george]

Thank you ched for the reply.
So wherever I find TX/RX in the controller will work? Per example even places 1,2,3.

[ched]

I think the safest way is to hook up to BetaFlight and see which uarts are in use. As 1 might be the usb connection. So look and see which uart is not in use and connect telemetry wires to that one.
That should sort out the electrical connections. The configuration of FRsky telemetry I have no idea about. Well I have seen some vids but no hands on experience. I think you set the uart you used to handle telemetry in BF and then search for sensors on your FRsky radio.

Good luck and let us know how you get on. Picys of your build are always welcome as everyone does things differently and it's good to see peoples ideas 

[AmiSMB]

I use UART1 or UART2 for telemetry on my SP F3 flight controllers as these are 5v based UARTS. UART3 is 3.3v only and I only use that for serial rx. Take a look at the SP F3 Manual.

HTH

[moraitis_george]

I would prefer to use UART1 as UART2 connector is broken. So, I should connect both TX and RX crossed with the TX and RX of the receiver?
And also, what is this limitation on the manual for UART1 means "MUST NOT be used when a cable is connected to the USB port"?

[ched]

I would prefer to use UART1 as UART2 connector is broken. So, I should connect both TX and RX crossed with the TX and RX of the receiver?
And also, what is this limitation on the manual for UART1 means "MUST NOT be used when a cable is connected to the USB port"?

Sounds like uart1 is used for your usb to connect to BetaFlight!!!! If you hook the FC up to betaflight and look on the ports tab (I think) then you should see a list of uarts and what they are connected to. If uart1 is used for USB you can not use it for telemetry. If you change uart1 to telemetry you will lose any way to connect to BetaFlight via usb!!!!!!!

So check which free uarts you have in BetaFlight. If the connector for uart2 is broken can you solder directly to the board?

[moraitis_george]

Hmmmm... It is freaking tiny.... but maybe

[ched]

As I said I know very little about FrSky but I do read bits and bobs. I'm not sure on the F3 board but sometimes you can remap a spare motor output to do other things. The other thing I have no idea about is if the FRsky telemetry is 'inverted' or not?
Some remapping info can be found here: https://github.com/betaflight/betaflight/wiki/Betaflight-resource-remapping
but it's not overly helpful.
Here is another link https://www.propwashed.com/betaflight-resource-remapping/ this one is much better and at the bottom it talks about soft serial and telemetry. So this might give you some clues.
WARNING make a backup of all BetaFlight settings before playing with resource mapping. Use the CLI and type in dump then copy all the text and save it as a text file. Then if it all goes pear shaped you copy your dump backup and paste it back into the CLI press return then type save. That should get you back to where you are in case it goes wrong.

Good luck and let us know how you get on.

[AmiSMB]

I would prefer to use UART1 as UART2 connector is broken. So, I should connect both TX and RX crossed with the TX and RX of the receiver?
And also, what is this limitation on the manual for UART1 means "MUST NOT be used when a cable is connected to the USB port"?

What I have found is that if the Telemetry is connected to UART1 then you have to make sure that you can stop it being used if you wish to connect USB. I had an MinimOSD on UART1 and found I always had to remove it for USB connection. I do find the plastic connectors on the UARTS break so usually use a fine solder tip and put the wires directly on the PCB pads.