Mini PC stick – one ounce to control thousands

Modecom Free PC mini computer

This year I found beneath Xmas tree a tiny box, and inside there was a mini PC of type HDMI stick. This dwarf is equipped with Windows 10 Home 32 bit, 2GB of RAM memory, 32GB of EMMC (20GB is available at start), Atom Z3735F processor and built in WiFi and Bluetooth 4.0 interfaces. Device is powered with 5V DC voltage and consumes up to 2A through dedicated micro USB socket. Other available ports are: microSD memory cart slot, USB 2.0 A port, USB 2.0 micro port (with USB A adapter) and HDMI plug. That’s it. 

Default application for this kind of PC is to be a multimedia center plugged into TV. I will not elaborate more in this aspect. It is enough to say that this unit works well in this area: browsing web pages, watching full HD movies (also in YT) and other basic tasks are not a problem for Free PC. I wanted to test this item as controller of astroimaging setup, because it fits well my new AstroLink mini project 🙂 

To make all run I needed to perform following steps:

  • installing remote desktop (because Home edition does not have it). I needed to install RDPWrap (https://github.com/stascorp/rdpwrap/releases) ro other favorite remote desktop server. Then I performed next steps using remote control
  • installing ASCOM 6.2 platform. This time I needed to switch on .NET 3.5 (there is only 4.6 in the Win 10 Home). Right click at Start button, then Control panel -> Applications and functions -> Turn on or off system functions and select there .NET 3.5. Then OK and ready
  • all other software caused no problems. EQASCOM, MaxIm DL with GSC catalog, FocusMax, camera and filter wheel drivers, PlateSolve 2.0 with APM catalog and Cartes du Ciel with Tych and default catalogs.

And that basically it. After all the installations there is only 15GB space left at EMMC drive – so for some “real” work we need to add microSD card to store our data. Fortunately microSD prices are pretty affordable. Next step was to plug my astroimaging setup into the stick. I took it to my skyshed and connected to 5V power supplier and to 5m long USB cable that controls my setup (there is USB2.0 D-Link hub attached to OTA that splits USB signal to components). I pressed ON button, blue LED has been lit, so I turned back home. I’ve been wondering if mini PC built in WiFi antenna is good enough to provide decent connection (there is 20m distance to skyshed and one thick wall), but it quickly turned out that is no problem. Connection speed was as good as with skyshed router – system indicated 72Mbps and file transfer speed is good. Remote desktop control at 1600x900x32 resolution is smooth.

 

HDMI stick at my astroshed laptop keyboard
All connections – 5V 2A power and USB cable to astroimaging setup.

 Components of my setup have been recognized and installed flawlessly, I only needed to point to Arduino drivers for my AstroHub device. Then I performed all usual steps when starting session: start AstroHub panel, power up mont, power up heaters, power up cameras, start Maxim, start EQASCOM, connect devices to Maxim – all these steps  caused zero problems. This night sky is clouded, so I made first tests under the roof. I made a few dark frames, a few shor sequences, and one longer two hour sequence and all looks fine so far. 

Remote session with Maxim

The thing that bothered me the most was mini PC performance. But in my opinion it is good enough for controlling deep sky imaging setup. Maxim, AstroHub panel, EQASCOM, FocusMax and PlateSolve software start in acceptable time, and once they are started they work smooth. Switching between running applications is fluent and causes zero or minimal lags. I also installed pretty demanding application – Cartes du Ciel. This one starts in less than 10 seconds, and works not so smooth (with a few more object catalogs switched on). But is is still usable and switching between CdC and other running software causes minimum lags.

Work with Maxim is comfortable. Basic operations on 16Mpx images are smooth. Reading full frame from QHY163M camera takes less than second – usual time for USB2.0 configuration. Saving this frame to EMMC storage takes about 3 seconds – still acceptable value for deep sky imaging. I have not yet tested microSD card. Processes that require more CPU power runs slower than at my sky shed laptop (CoreDuo 2.4GHz, 4GB RAM). For example plate solving for one of session frames takes about 20 seconds on mini PC, and about 5 seconds on my sky shed laptop. I also recommend performing calibration only with master frames. Using calibration library (in my case over 100 frames, 16Mpx each) definitely will kill mini PC. 

Under heavier load – still acceptable performance

So far I am pretty happy with the results – my two main concerns were WiFi connection quality and performance, and it looks they are both good enough. I plan to do more tests soon, as soon as clear sky will come: storing at microSD card, APT, PHD, DSLR work and maybe some planetary imaging with selected ROI.

Clear skies!

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