Fitting a microhard on the Bixler

So I'm currently trying to fit a microhard n920 onto a Bixler, and unfortunately I don't see a way to do this without also having the dev board (doesn't look like they have a small breakout board I can wire up to).  I've managed to get it to fit into the fuselage, but don't see a way to connect the RS232 to the TTL converter. Anyone have a solution or know of some RS232 angle adapter that might work?  Alternatively, is there a way to wire this using the RS485/422 pins?


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      • Hallo ... this may depend upon several details:

        0) which i/f board you are using to connect pixhawk to n920 unit? What bout GCS?

        1) hardware connection

        2) logic levels,

        3) settings of the serial ports of both n920 units and pixhawk/gcs as also n920 units ports,

        Below the MOST common pitfalls for such points:

        1) always check for tx / rx port matching. For instance if you are NOT using MicroHard i/f board keep in mind that Microhard describe n920 units port from the point of view of the connect device so if you read TX on n920 user manual you are going to connect this pin to the transmission port of your device (pixhawk or gcs).

        2) Microhard n920 units ports are LVTTL then if you are going to connect it to a device with different levels (i.e. TTL or RS232) you have to properly translate levels. Pixhawk telemetry ports are LVTTL so you may keep levels unmanaged (but keep in mind point 1) but in GCS I think that you have to handle this.

        3) Speed settings of pixhawk telemetry port, GCS serial port, n920 data port speeds MUST match i.e. if you set pixhawk telemetry port to 57600 bps the same speed setting must be set on every other device and the RF data rate of n920 units should allow such bandwidth to be handled.

        Hope this can help you.

        • Hello dear

          thank you so much for your concern about the matter

          actually i have gone through all of the steps you mentioned above

          the point is that when we check the performance of the link with the serial terminals like h-terminal or docklight we find no problem sending or receiving data and it receives what ever we send. (but there is a problem in this stage that we can not use loop back meaning if we connect rx to tx in one side, we wont find any data returned back when we attempt to send data)

          the problem arises when we want to connect to mission planner that we encounter with time out error.

          now if you have connected to mission planner with the help of n920 data link, please give me a video of that or the settings you have used. it would be of course of your kindness and so would be appreciated.

          thank you so much


          • I think that you have to go a little deeper investigating why you cannot see data coming back using an hardware loopback... without this working there's no chance the full system will work.

            Regardi settings: I will do a capture of the registers configuration and post here next week... do you need a point to point or point to multipoint topology?

  • The N920 is designed to be integrated as an OEM module, that's why you won't find any breakout board. Making one is really simple ( if you have basics skills in electronics) you just need to be careful sizing the proper voltage regulator.

    Also I can see form your setup that the modem has no airflow for cooling around it. Be careful the N920 gets pretty hot and needs some light cooling... if you don't, the power output will be decreased till the modem will shutdown for overheating. 

    Good luck. 

  • Hallo I'm currently designing a board that fits a microhard n920 radio unit (just the nano unit neither the ip rev nor the full dev board) into a very small board with a level translator. If you still need it I can send you the project (i mean schematics and gerber files).

    Best Regards,


    • Hello Mike,

      I am trying to make a break out board for my microhard N920F integration. Can you please send me your project files so that I can check them out and possibly I will have a couple of them made.

      Thank you,


      • Hallo,

        of course yes. What files you need? Gerber or project ones?

        Best Regards,


        • I would like both if possible. I don't really know what I am going to need. Electronics company wants a gerber file, but I would like as much information as possible to start. Can you recommend a free electronics software suite that will allow me to edit the files as well. I will start by sending gerber file for a quote and then see if I can modify the board to suit my needs a little better as I want a df13 plug on it so direct conenection to the ardupilot and pixhawk using the df13 plugs. I can hand over the files to my electrical friend who can do the modifciations for me. Thanks in advance for the headstart, You can pm me the file or post them on the site by uploading files.

          Thank you very much,

          Jaron Denson

          • Hallo,

            I will send you my files ASAP (I got files @ my office and I'm out for
            holidays right now) .

            There are many free pcb design software, KiCAD is my favored but many
            others have nicer features. For 'compatibility' with my own work I would
            suggest you to use KiCAD but you may give also a look to Eagle
            PCB, DesignSpark PCB (this one is pretty good and allows to compile BOM
            bound to RS/Allied components).

            Best Regards,

            • Well, thank you very much. When do you think you will be in so I can send you a friendly reminder in case you forget after your brain has been flooded with holiday cheer? Did you do a DFM check on it? Is it pretty much ready to go?

              We have Eagle  here apparently but I can grab KiCAD to interpret your project.

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