MiniAPM v3.1

Hi,

I noticed a reference to this in a blog post:

http://www.goodluckbuy.com/miniapm-v3-1-mini-ardupilot-mega-2-6-external-compass-apm-flight-controller-for-multicopter-fpv.html

It looks too-good-to-be-true to me.

I was wondering if anyone had already purchaed one of these, and if so - are they any good?

Shane.

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  • Hi All, I have bought a few as I wanted to try it out on my Mini250mm as well.  I have powered them on and all is good.. tested them with APM Planner Tests and all was okay there as well.

    I will start to build out an new mini for testing in the next few weeks... but i have some photos to share on Pin-Outs if it helps.

    3701806632?profile=original

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    Diag 1.jpg

    Diag 2.jpg

    MiniAPM Ports.jpg

    • I have seen some clever ways of hooking up the GPS and Compass, but no-one has shown how they have hooked up their inputs (Rx) or outputs (motors/servos).

      If anyone has worked out an elegant way of doing this could they please post pictures.

  • 3701806943?profile=originalThis is my first post so take it easy. My MiniAPM arrived today and I managed to get the GPS and external compass connected by backing out the crimps and making a new cable without cutting any wires. The only problem was the 3.3v supply to the compass which I stole from the GPS linear regulator as you can see from the mod wire on the board. I plan to glue this wire down to with hot melt glue to prevent vibration problems. Next is the power module which I suspect will need some wire cutting.

    • I like the way you have hooked up the GPS/compass.

      I am surprised that we have to do this sort of thing though. Surely the designers would have known that external GPS/Compass modules would typically have two cables (not one).

      Does anyone know of an adaptor board or cable which would allow me to plug my external GPS/compass straight in without making changes like this, or soldering wires like @Terry Brooks?

    • Thanks for the info Andrew. Looks good so far.

      Please continue to keep us updated on your progress.

  • I got APM Mini from infinityhobby, working good so far. Using rctimer cn-06 gps, telemetry, ppm, ubec for powering. All flight modes are just fine, stable with stock pid on 450 quad.
    Yeah After reading Jani's explanation I am not sure either about it's reliability.
  • Probably this much simplified APM-mini is not going to be very reliable. As Jani already mentioned, if the capacitors are not there, the ATMEGA 2560 is going to be very sensitive to any voltage spikes/drops or noise/interference and may brown out or reboot during the flight. I'm afraid of any crashing due to FC failure, looks like I'll stick to the large original APM 2.6, afterall it's not that big, without the case.

    • maybe some caps to smooth out the Vcc would do it? we are using caps on the standard apms anyways..... 

      • Developer

        Artem, you maybe don't know meaning of decoupling capacitors. Having big capacitors somewhere on output pins does not work. All sensitive electronics needs to have decoupling caps just few millimeters away from power input pins. Usually we are talking about 100nF ceramic caps along the power traces and other areas. Whole purpose of these caps are to smoothen out power inputs and block harmful frequencies to enter on the "device". 

        Different size capacitors are blocking and filtering different frequencies. Doing decoupling is kinda "magic". Making PCBs is not just placing components on it. To make a good PCB you need to know how different frequencies are affecting PCB design, how components and component groups are affecting, how traces and trace widths are affecting on it.

        Different trace lengths and widths are "collecting" outside radio frequencies and these frequencies can be really harmful for your electronics. More sensitive electronics on board, smaller the board is, more important it is to know how to work with components/pcbs/frequencies.

        Just as an example, you don't want to get your 2.4Ghz RC Controller frequencies to hit your power input on your CPU as that could cause major problems for you. Or getting some RF frequencies on power regulators can cause all types of weird behavior like rectify all your protection diodes, servo jitter, regulator voltages going up and down, CPU crashes and so on... 

        • Jani, I have OP revolution flashed with Ardupilot fw, tested several times with good result. Considering its form factor, will it suffer the same problem with apm mini according to your explanation. I believe revo is good quality board, but today I learn someting about being mini. thanks Jani

          Yana
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