Hi Everyone,


Maybe you know, i'm working on Open Source RC (OpenLRS) project since 1-2 years and we released it in this summer.

Today I just finished the firmware v1.10 with transparent serial bridge!

This mean, you can talk with autopilot or other telemetry modules without any extra telemetry device. Your OpenLRS Rx and Tx can handle this mission.


Download link:


OpenLRS Forum link:


Rx to Tx transmission supporting 750 byte/seconds (not bit/second) without any problem. 
It's handling 9600 baud signals with %80 traffic.
But Tx to Rx (ground to air) transmission sharing the servo communication bytes and we are not suggesting more than 100 byte/second for ground to air transmission.

We are suggesting 115.200 baud serial speed (%5 traffic) for clear serial. If you want to use 9600 or near speeds dont forget; Atmega328(with Arduino) can read the signal with hardware without any problem, but it have to wait for next byte when writing. You must finish the writing before reading next RF package. This is why you need high speed communication when writing something on the serial out. 
As a reference: In this video, i'm using 9600 baud on GPS side and 115.200 baud on computer side.




Old Diydrones blog posts about OpenLRS Project





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  • Melih,


    Thanks for your valuable advice. As per your instruction I've already started the project. I've bought 2 Arduino uno. Already studied the Arduino forum for "serial to servo" firmware sample, it seems easy to implement for my project.


    But I'm facing difficulties in writing a ground station software. Because I've very less idea about programming. Pl suggest me how can I do this. If possible pl send me some links. Thanks in advance.

  • Hi Jakaria,

    Sorry for my later reply.
    I'm strongly suggesting "Arduino Uno" platform for your project. It's including USB serial for your PC connection (and firmware loading)   and have a lot of "serial to servo" firmware sample on the web. Just write your own ground station software and  send the servo commands to arduino over USB serial. Arduino forums helps you for details.

  • Some correction on the converted baud rates for serial 3.

    9600 = 9, 19200 = 19, 38400 = 38, 57600 = 57, 111100 = 111, 115200 = 115

    Goes under the SERIAL3_BAUD parameter in the Mission Planner interface.

  • Hi Melih,

    I really like that you make things simple for us. Also your views attract me. At various places I found that you are interested about PC based autopilot which really attracted me. As you are an expart, I'd request your assistance regarding the project which is described below.

    Suppose I'm in a real Ship and I want to run it with a PC based autopilot and Gamepad. GPS should be connected to the PC and all calculations should be done by the PC. Then PC should send the final servo commands to a simple Microcontroller and Microcontroller will do the speed control, servo control etc. If possible I want to interface the project with a good Ground Control Station which supports Gamepad. No RC is needed as I'm onboard the ship. Pl suggest me  elaborately because I've almost zero knowledge about programming.

  • Moderator

    Just want to point out that while Melih mentions changing telemetry port baud rate in APM source, you can also change it in Planner with no need to edit source. Look for Serial 3 in the parameters list and change the value. Just enter 48, 96, 19 or 57 and click write parameters.

  • Developer

    Currently ArduCopter, ArduPlane used 57.600 baud for all telemetry communication as default and XBees handle those well. For really long distances you need to lower down telemetry speed but such as ArduCopters you usually cannot even fly so far that you will start having problems with 57k.

  • @Andrew, I guess you can configure the APM from source code for 4800 baud or 9600. because most of xbee modules supporting maximum 9600 or 19200 baud.

    @Amilcar, Thank you very much, i will read it as soon as possible.


    Here is the funny code implementation for OpenLRS :)

  • Melih I've learned git by listening to a Linus Trovalds talk at google headquarters, and by reading the git book at http://book.git-scm.com/index.html just make sure to skip the introduction chapter. It is confusing and un-necessary for normal users. Just skip directly to chapter 2

  • Awesome. I have been looking at OpenLRS for a while and was wondering when this would be implemented.


    For those in the UK - Open LRS can be configured to use the licence free 459Mhz band - which is useful because it avoids the use of 2.4GHz - which is commonly used for FPV video transmission. Perhaps this could be an alternative to the 2.4Ghz XBees for telemetry?


    What's the minimum baud rate needed by the APM anyway?

  • @Amilcar,
    1. Because of flexibility of file. I wrote it as a pde file and we are changing something in every version. Maybe i can do it at the future.
    2. Google code is very chaotic for me and i dont have time to learn it. Maybe i can do it someday but not now. Do you know any "simple" article about it?



    As you can read on our product page, Booster is unidirectional device for long range features. You cant use it with telemetry features.


    @Kim,  I'm not sure about it. Because it's generating rf pulses and they affects the sensors of oilpan. A little distance is better for this kind of devices.

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