Home Forums Everything about the Mini Tricopter Frysky X4R SB S.Port Telemetrie

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    Dear All,

    my MiniTri including the onboard Naze 32 and Davids electronic pack will arrive soon. VBAT will be 3S first and than 4S.
    I intend to use a X4R SB RX with inverter or directly with the new CPPM firmware. My question now is about the VBAT voltage monitoring during flight time.
    Can i use the S.Port to monitor the voltage just connecting the S.Port RX wire with the telemetry Pin of the Naze board? If not what and where to connect?
    Or could I use the AIN (analog in) of the S.Port which is a 3.3V related Input and a voltage divider related to VBAT will be needed.

    Any thoughts or different ideas are highly appreceated.

    Thanks and best regards



    SBUS has much less latency compared to CPPM and has more channels. You need to use one UART for that.

    If you don’t need anything else for telemetry than battery voltage, I would use the AIN on the receiver with a voltage divider.

    You can get the inverted signal straight from the receiver if you open it up and do a bit of soldering. Check these:


    Thanks a lot for your suggestions.
    Not having the Tri right now, do you have a schematic which pin on the Tri naze board belongs to what pin and port on the regular one?

    If there are different suggestions regarding the s.port telemetry just let me know.


    The telem pin on the Naze32 is for D series telemetry. For s.port telem you need a UART. This does make it tough on the Naze32 with only 2. However, I believe if you use UART1 for s.port, which the USB is on, if the board doesn’t detect telem protocol on startup it will then assume you want to connect USB. That will leave uart2 for sbus. For the mini-tri that’s probably fine, you probably won’t put on any other gadgets that need high speed UART.

    If you want to do the sbus hack it is much easier than in that video. Read this thread.
    Just need to remove a resistor and then solder a wire from the input of the inverter chip to the output of the resistor. This way makes it easier to undo the hack if you want.


    Thanks Kevin,

    that helps a lot. As i wrote earlier my Tri has not arrived yet. When looking at the pics and videos I´m wondering where UART1 and UART2 are physical located (pin wise) on Davids Naze 32 main board. Is one of the receiver Pins dedicated to UART 1 and/or the TX/RX pins the right side of the board.

    Kind regards



    @Kevin would a soft serial port for telemetry be possible instead of an UART port? How would you connect it?

    (Have a X4RSB on order)


    @Terje as far as i know softserial is limited to 19200 baud and s.port needs a faster rate.


    That explains why my telemetry wasn’t working on my x4rsb. Very helpful stuff.

    Is there anything I should be doing to improve my latency if I am using the sbus to cppm converter cable?


    Ugh, this is what sucks about reading up on FrSky telemetry online, you need to make sure which version they are talking about.

    You cannot share uart1 with smartport telemetry.

    If the X series needs a faster baud rate than 19200 then you can’t use soft serial.

    This is why I am tempted to get an SFRacing3 board. Expensive, but a bunch of hardware UARTs. Though I think I saw another flight controller on rcgroups.com that was cheaper and had three UARTs which would work.

    The CPPM firmware does look inviting then with the Naze32 since you will want to use uart2 for s.port telem.


    @Kevin or all the others, let´s say my noob problem is where on the MiniTri Naze32 board is the connection Pin for UART1 (I suggest its the TX RX on top of the board) and where to find and connect UART2.
    Thanks for your answer



    That is a good question.

    Based on the pics from the shop page When looking at the USB port side not sure which UART pins are on the top right are. However, it appears the other side have both UARTs exposed. Someone with the frame can you post a better picture of the pins and pads available on both sides of the board?

    Naze32 Tricopter frame


    I believe that the picture on the shop page is perfect. There are no pads on the top, only the holes, which are also on the bottom. UART2 is available on the receiver pins 3 & 4 when not using PWM receiver.


    Thamks a lot for that information!!! I would have tested this now with the board that arrived this afternoon. But the board is faulty :(. (No way to get a stable connection with Cleanflight. It looks like one chip on board has a problem. Lots of i2c errors) I allready informed @David and hopefully get a response soon.

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