Remote control your GoTo telescope mount using a Raspberry Pi and SkySafari

SkySafari is a great astronomy app for smart devices like the iPhone, iPad and Android.
The SkySafari Plus and Pro versions add the possibility to remote control your GoTo telescope mount using the special SkyFi adapter.
This adapter sends serial (RS-232) commands, received with a wireless connection, to the handset of the GoTo mount.
Using SkySafari in combination with SkyFi increases the number of objects you can observe and current events in the sky (like comet PANSTARRS at the moment) are found easily this way.

I was wondering if it would be possible to create something like SkyFi using the Raspberry Pi.
And yes, it is possible. Quite easy actually!

What do you need?

  • Raspberry Pi configured with a working network connection (wifi preferred, of course).
  • USB to Serial cable.
  • GoTo telescope mount
  • PC Serial to GoTo handset cable. Shipped with your GoTo mount.
  • SkySafari Plus or Pro
  • Basic Linux knowledge

Now how are we to receive the commands from SkySafari?
This is done by the Serial To Network Proxy (ser2net).

Install ser2net:

sudo apt-get install ser2net

Add the following line, using your favorite text editor, at the end of the ser2net configuration file (/etc/ser2net.conf) which contains the port where ser2net is listening on:

4000:raw:0:/dev/ttyUSB0:9600 NONE 1STOPBIT 8DATABITS

In this case, I chose port 4000. You may choose another port but be sure it is between 1024 and 65535 and does not conflict with any other daemons listening on the same port.

Restart the ser2net service with the new configuration:

sudo /etc/init.d/ser2net restart

Next, configure your telescope in SkySafari.
My setup has a SkyWatcher SynScan GoTo on a EQ3-2 equatorial mount.
Be sure to enter your setup and don’t copy my settings bluntly 😉

skyfi_settings

The IP address in the picture above corresponds with my Raspberry Pi. Of course, you should enter the IP address of your Raspberry Pi.
Same goes for the listening port. I’m using port 4000.
If you configured a different one for ser2net, enter that one.

After that is done, you should try to connect SkySafari with your mount in the Scope menu and you’re off to go!

← Previous post

Next post →

15 Comments

  1. Stephan

    Hi,

    thanks a lot for sharing cool raspeberry project. I have already installed and configured everything as you suggested and it works nicely.

    However, I have only tested the system in my home wifi network, i.e. dynamic IP for the raspberry. I’d love to use it in the field at our local observatory for public observations. There we have no wifi network. Is there a way to assign the raspberry a static address and use point-to-point like communication?

    Cheers and clear skies!
    Stephan

    • Astroland

      Hi Stephan

      Great that this project got its use for you.

      As for your ‘problem’ there are 2 solutions.
      A more complicated (but costless) one and a simple one which involves buying a small inexpensive piece of hardware.

      The complicated solution is to convert your Raspberry Pi into a WiFi access point.
      You can do this using hostapd. I found some clear explanation on this page: http://itsacleanmachine.blogspot.nl/2013/02/wifi-access-point-with-raspberry-pi.html
      This way you can create a mobile WiFi network using the Raspberry Pi, which also functions as a DHCP server now for distributing IP addresses.
      Doing this is a project on its own. Good for yet another sunday afternoon 🙂
      The only thing you have to keep in mind is that you must turn off the access point functionality when you’re back home because it may conflict with your WiFi router at home.

      If you want instant gratification, you’ll have to buy a small access point.
      Nowadays you have these tiny access points from TP Link (TP-Link TL-WR702N). They cost around 20 euros (on Ebay) and you can power them using USB (with a USB converter plug for your powertank).
      When you’re out in the field, your Raspberry Pi and your smart device connect to this access point.

      Hope this give you some ideas.

      • Astroland

        Somebody hinted me another solution: let your iPhone or Android phone be an access point.
        I haven’t tested this but this might work too.

        • Has anyone tested the solotion with the iPhone to be an acces point? This way you only really need a raspberry!

  2. The pi is, I guess, powerful enough to also do tracking via a webcam and a second scope. Would make for longer exposures 🙂

    • Astroland

      Yes, I’ve read that some people successfully managed to do this using lin_guider.
      OpenPHD + INDI was a bit too slow for the Pi.

      The Pi rocks 🙂

  3. Ashish Mehra

    Hi,

    Thanks for this post. I can’t wait to have my raspberry Pi controlled GoTo telescope set up going!

    Can you please recommend a good USB to Serial cable? That’s the only component missing for me and there are various kinds of all sorts of prices available online.

    Do they have to be DC powered ones? Does Linux natively support most usb-serial cables or should I only get those that come with a Linux driver? Any particular baud speed I should look out for?

    Thanks,
    Ashish

    • Astroland

      Hi Ashish

      You don’t need a DC powered one.
      The one I’m using is from Konig and works just fine. I don’t know if this brand is available in you country, so it’s a matter of trying.
      I heard that people with Sitecom cables have good results as well.

      Also most of the cables are detected by default by the Pi so you don’t have to install drivers.
      In my blog post you can see the settings of ser2net. I configure the ser2net daemon to handle a speed of 9600 baud.
      This is fast enough for operating your mount.

      Hope this helps.

      • Ashish Mehra

        Hey there,

        Thanks for getting back to me. I went ahead with a basic serial-usb cable (approx £1.50) and the setup seems to be working well!

        Now I am trying to figure out a way to auto-align the telescope. My GoTo Mount requires me to use the Brightest Star/2-Star Alignment process manually but considering that SkySafari can use the phone’s GPS there must be a way to auto-align, right?

        Thanks,
        Ashish

  4. Scoobie

    Hey there,

    i’m looking into hooking my Nexstar SE to a Raspberry Pi. I found lot’s of cool ways to do so. My problem is that i can’t seem to get my rig to align. I read Ashish’s post about auto-alignment….

    Did anyone solve this??

    That would be THE solution for me!

    Thanks for an answer:)

    Scoobs

  5. Nice to read this Astroland!

    I am going to try this for sure!

    Instead of a USB to serial adapter, this might be an option;

    http://www.davidhunt.ie/add-a-9-pin-serial-port-to-your-raspberry-pi-in-10-minutes/

    If you search for “Max3232” on a famous chinese webstorem you’ll find a serial connector for the RBPi for less than 4 USD, Don’t know if that will work but i am going to try.

    Thanks

    Jasper

  6. Nice response in return of this question with real arguments and telling all
    about that.

  7. Jasper

    Hi Astroland and others,

    still waiting for a male-male 9 pins plug for the RasPi MAX3232 serial connector to connect with the serial cable to the mounts handcontroller (Skywatcher AZ-EQ6).

    But in the meanwhile i succeeded with an usb-serial adapter plugged in one of the RasPi’s usb ports and SkySafari 4 plus on Android. Thanks for this website!

    Though sometimes response is slow. Maybe that can be related to the Baudrate setting? Can i try higher setting than 9600, or might that be harmfull for the handcontroller?

    I did not get a change to try alignment yet but SjySafari seems to have an easy-alignment option.

    Off-topic: Another nice project is running lin_guider on the RasPi with webcam or other as guide camera.

  8. Hi Astroland and others.

    Very thank you for publishing this article, “Remote control your GoTo telescope mount using a Raspberry Pi and SkySafari”.

    I have Raspberry pi 2b, I did like in the description and works flawlessly.

    But is it possible to create an access point on presentation of a wireless router TP-LINK TL-wr702n to control the telescope in an open area where I do not have internet access?

    Greetings

  9. Jonathan

    Great write up. Worked first time for me. Thank you.

Geef een reactie