Raspberry Pi and Astronomy

[Gina]

Has anyone used the Raspberry Pi to control astro equipment and/or capture astro images?  I'm hoping to do this but uncertain as to whether the RPi is up to handling Indi etc.  I plan to use the RPi 3 with WiFi to run my all sky camera but the requirements for that are much simpler than controlling mount, filter wheel etc.  I know the RPi has already been used for an all sky camera.

Wireless All Sky Camera

Any information would be much appreciated - thanks in advance

[psamathe]

I've set it up driving my mount and Canon DSLR and only played around so far.  Straightforward to set-up and get going.

In my playing around I have found my Canon images are large and so take longer than I expected to download - so playing with wider channels Wi-Fi, better signal strength and investigating local storage of images on the Pi (though not had much time to play around for a bit).

Still to use "in anger" so my comments/experiences are limited.  I am impressed with the RPi3 and for running an Indi server I can't imagine the processing loads would be excessive assuming you are running the client remotely (I have seen some people talk about running Kstars/Ekos on the RPi3 and access through VNC thought it sounded a strange way of doing things to me).

However, one really good (in my opinion) thing about the Indi Server architecture is that it can be run in a distributed manner.  So you could have 2 RPi3s one handling some devices, others the other devices.  You could go up to several RPis if you wanted/needed - one becomes the "master" server (probably a bad terminology from me) and on the Indi Server start command line where you specify the various drivers you include the name/ip address of the device the particular driver is running on (i.e. omit the name/IP address and it's on the local RPi/computer, include the name/IP address and that device control is accessed on that device).  The client than talks to the "master" Indi server and has no knowledge about the distributed architecture the server is running.  So e.g. RPi A talks to the client and handles driving the mount whilst RPi B handles the auto-guider and RPi3 handles imaging and filter wheel.  (It's a feature of the Indi Server not anything specific to the RPi).

It provides a very flexible architecture and allows additional processing to be added as needed and very easy to configure (just a slight modification to the startup command line for the Indi server.

Ian

[cjdawson]

Considering that when I started out proper in astronomy, the computers of the day where from the pentium 3 range and running at about 800Mhz, 1Ghz was top of the range stuff.  I'm wondering if actually the PI 3 is more than up to the task.  After all, it's a quad core device, so if 2 cores are doing image processing stuff, that still leaves 2 cores free for running filter wheels etc.  I think the most intensive that you could ask a PI to do with be to be an auto guider.   Controlling filter wheels and moving the mount shouldn't be that much of a load on the device.

[psamathe]

One constraint or maybe something people overlook is that whilst the RPi3 is a 64 bit processor Raspbian only runs it in 32 bit mode.  So it's fast but not at full 64 bit capability.  And it seems unlikely that anybody will bother to create a 64 bit kernel (given the 1GB RAM limit).

That said some people seem to say it's an excellent 32 bit processor that also happens to run in 64 bit mode so I've no idea quite what the impacts or gains are (just repeating what I've read elsewhere).

Ian

[ringz]

Eben Upton (founder of the Raspberry Pi Foundation) is the person who said that the current processor for the Pi 3 was selected because it is an excellent 32 bit processor.

He also said that Raspbian would carry on as a 32 bit O/S. I think his interview is on the Raspberry Pi website

[cjdawson]

Just wait, I'm sure that it will change in time.  Just as when Bill Gates allegedly said "640K ought to be enough for anyone".

64-bit processors offer more than access to more ram.  The chips can offer more processor instructions to make things like translating blocks of video memory more efficient (just one example as it's already on the PI) you can do more with by having access to all the 64-bit registers (I mean on the chip without having to access L1 or L2 cache)  all this adds up to opportunities for software to be smarter in the way it works and therefore more efficient.  Of course, the programmers need to be clued up to exploit these nuances. 

[ringz]

The processor has moved from an ARM 6 architecture to ARM 7 architecture that has made a big difference. But the new instructions/capabilities are not being used.

 

[kens]

Check out the tutorial videos here http://indilib.org/about/ekos/video-tutorials.html

I'm pretty sure they were done using a Pi2

That's what I have but I'm still at the experimenting stage and haven't used it in anger

[Gina]

Thank you Ken - that looks very useful

[Gina]

I like the idea of distributed control with Indi using several RPis.

I see the following functions needed :-

1. Run the mount
2. Guiding
3. Controlling filter wheel
4. Capturing image
5. Focussing scope

I expect some of these could be combined eg. focussing done with Arduino from USB on RPi.  I imagine image capture may require all of one RPi but don't know.

I also have NB triple rigs where I have three cameras with either three scopes or three lenses for widefield.  I which case the list becomes :-

1. Run the mount
2. Guiding
3. Capturing image & Focussing scope/camera 1
4. Capturing image & Focussing scope/camera 2
5. Capturing image & Focussing scope/camera 3

[Gina]

Can Indi handle multiple imagers?

[psamathe]

3 hours ago, Gina said:

Can Indi handle multiple imagers?

I don't know but if not I'd have thought it's just a matter of running separate clients each connecting to the imager of a different Indi server (and those clients could presumably be on the same computer in different virtual machines).  Or maybe some way of running separate instances on Kstars/Ekos or a "lighter weight" image capture app (supporting Indi) for the different imagers whilst the main RPi/client controls the single mount.

I'd have thought running more than one imager would add a significant level of complexity (maybe more user complexity) as it's not just more than one imager but also more than one filter wheel (each of which needs to be associated with its imager) and more than one focuser (again needing associating with it's imager) and then you'd need multiple scheduled (given that Ekos now includes a scheduler), etc., etc.  If it were me I'd be going for the multiple clients and one imager per server (excl. auto-guider imager) - if only to keep the usability more straightforward.

But, I don't know Indi's capabilities in this regard so about are my thoughts and guesses.

Ian

[Gina]

Thanks Ian   I will probably run each camera and focussing from a separate computer viz. RPi and yet another to control the mount and run guiding camera and software if I use guiding.

[kens]

13 hours ago, Gina said:

Can Indi handle multiple imagers?

It can certainly connect to multiple imagers. It sees my guide scope/camera as just another imager and I can select either in EKOS. But EKOS seems to have just one tab for the imaging setup so I suspect it will only allow one sequencer at a time. Best to ask over at the Indilib forum. http://indilib.org/forum/general.html

[Gina]

I'm wondering if a serial output from the RPi could be used to run a mount and whether this would be better than USB and a USB to serial adapter.

[riklaunim]

Both are UARTs so they should work the same.

[cjdawson]

Just a word of warning about the UART on the PI3.  There is a problem with it in that the Bluetooth and Wifi addtions have messed up something on the UART timings.   I discovered this when I created my PI3 home server (DNS, VPN and Strat 1 NTP server) the NTP Uses a GPS for time signals via the UART on the PI.  It works great on a PI 2, but I can't get it working on a PI 3.  The problem has something to do with a timing issue.   I came across this in march, so with any luck there will have been a proper software fix produced by now.

[wimvb]

On ‎2016‎-‎08‎-‎18 at 18:53, Gina said:

I'm wondering if a serial output from the RPi could be used to run a mount and whether this would be better than USB and a USB to serial adapter.

I use HITECASTRO EQDir cable and the EQMOD_telescope driver on indi, RPi 2 with Ubuntu Mate

Works great, but have only tested very basic things with this.

I like the idea of distributed computing. RPi's are so cheap, no need to overload them.

But to missquote Tolkien: "One ring RPi to control them all."

[Gina]

Thanks

[Gina]

Found a web site for Indi that describes how to install Indi on a Raspberry Pi in full detail.  They suggest using "Ubuntu Mate for Raspberry Pi 2 & 3" as the OS as that has got most of the required apps and libraries already in it.  With my present almost unusable internet connection of around half a megabit per second, downloading over a GB will take ages so I've been trying to find it to buy on micro SD without any luck.  Guess I'll just have to set it to download overnight before I go to bed.  The 1.1GB zip download will take about 6 hours.

[Gina]

I've started the "Ubuntu MATE for RPi 3" download and actually getting much better speed than recently.  I've also ordered a couple of micro SD cards to put it on, from Amazon due to arrive tomorrow.  Then I shall start sorting out the RPi and Indi.  I might use an RPi indoors for control - I'm that impressed with the RPi.  Meanwhile I'll collect up all the info I can ready to go when I get the goods.

[gentlebear76]

2 hours ago, Gina said:

Found a web site for Indi that describes how to install Indi on a Raspberry Pi in full detail.  They suggest using "Ubuntu Mate for Raspberry Pi 2 & 3" as the OS as that has got most of the required apps and libraries already in it.  With my present almost unusable internet connection of around half a megabit per second, downloading over a GB will take ages so I've been trying to find it to buy on micro SD without any luck.  Guess I'll just have to set it to download overnight before I go to bed.  The 1.1GB zip download will take about 6 hours.

Is this the tutorial on the indilib site? I'm following your endeavour into RPi with great interest. I tried it a couple of times myself but had problems with the qhy drivers so I decided to drop it. However, it is a very capable suite so I might return :-)

/Michael

[Gina]

Yes - here's the link :- INDI Library on Raspberry PI.   They explain exactly how to add the libraries to Raspbian but not to MATE other than " you can get all the bleeding edge INDI and KStars directly from the Ubuntu INDI PPA, no need to download and install packages manually! ".  I presume you just add the repository.

I've got the Ubuntu MATE download now - much quicker than I expected.

[psamathe]

Also a couple of threads on UKAI from an admin trying Indi on RPi http://ukastroimaging.co.uk/forums/index.php?board=117.0

Ian

[Gina]

Thanks Ian