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Raspberry Pi ?

fwm891

By fwm891
in DIY Astronomer

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riklaunim

riklaunim

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With additional electronics you can control stepper motors (found in mounts) or DC motors, servos (motofocusers etc.). If you can make a "mount" or a motofocuser our of raw parts you could use Raspberry or other similar board to control it. Pi camera can be used to some extent in planetary astrophotography (if you remove the lens would be best, but that's not easy to do).

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pete_l

pete_l

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Yes it has lots of potential. But on its own, out of the box there's not a lot you can use it for - astronomically speaking.

The biggest "plus" the Pi has is that lots of people have written software that lets it communicate with and control peripherals - or just blink some LEDs. But it means you do need to have those peripherals and other bits 'n' pieces.

I'd suggest also investing in a solderless breadboard [ google ] and a beginners pack of components.

And don't forget, you'll need an SD card with a Linux image on it (and a keyboard, and a mouse, and a power supply, and an HDMI cable+TV to plug it in to) , in order to do anything at all.

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Macavity

Macavity

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A lot of people seem to use Arduinos, which have a series of interface boards.

On the other hand, the Rasberry Pi has a friendlier developer environment? :)

But I note, with modest amusement, we now have the: Gertduino!

http://uk.farnell.com/jsp/displayProduct.jsp?sku=2344460&CMP=KNC-GUK-[removed word]-GEN-SKU-MDC&mckv=slJ1Yg5sV|pcrid|34849875128|kword|gertduino|match|p|plid|&gclid=CM714-zYnbsCFUrJtAodTigAxA

Best of both worlds? Or simply (pleasant enough) diversion from Astronomy? :p

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themaninthesuitcase

themaninthesuitcase

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If you have a search on here some one got open PHD running on a Pi with a QHY5, not sure how well it worked off the top of my head.

A pi is incredibly low spec so guiding and maybe it could act as a remote telescope controller but I wouldn't want to try run CdC or Stellarium on it, I'd set it up to receive commands from another machine (which I believe is quite doable looking at the settings in Stellarium).

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JamesF

JamesF

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If you have a search on here some one got open PHD running on a Pi with a QHY5, not sure how well it worked off the top of my head.

A pi is incredibly low spec so guiding and maybe it could act as a remote telescope controller but I wouldn't want to try run CdC or Stellarium on it, I'd set it up to receive commands from another machine (which I believe is quite doable looking at the settings in Stellarium).

Even attempting to compile CdC or Stellarium on the Pi could be quite a challenge, though obviously it could be cross-compiled.

James

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JamesF

JamesF

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Of course, my Linux capture application should work on the Pi.  It might be interesting to give it a go.  I'll see what I can do with ours.

The ASI SDK is available for the Pi and the TIS USB camera drivers should work (as well as SPC900, Xbox and Lifecam though the last two may need a little work).  There's no reason the QHY5 cameras shouldn't work once I finish writing support for those either, especially given that someone has already ported PHD.  The major potential stumbling blocks I can see for the moment are which version of Qt is available and what the most recent kernel version is.

Storage of captured data might present a problem, but there must be a way around that.  Perhaps the Pi would be better-suited to some sort of video astronomy application where the data is being stacked and displayed on-screen.  I don't think it would be too hard to take the code I already have and turn it to such an application.

James

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Chris Rowland

Chris Rowland

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I've heard that Stellarium has been compiled on a Pi and it took hours.  But does that reflect in it's operation speed, especially if the hardware based graphics are available?  the Pi people should know.

Personally I use Arduino and PicAxe for hardware control.  The Arduino has more I/O than the Pi and seems easier to me because there is no operating system to get in the way.  The PicAxe is very simple to program and can be run at very low power levels.

I have a PicAxe with a digital compass, transmitting dome position wirelessly to an Arduino that handles the dome motor and position control and a PC for the communication with the scope and the UI. The PicAxe is powered continually off 2 AAs, it spends most of the time asleep, waking up occasionally to check if the position has changed.

My next project is a weather monitor, something to check on cloud, rain, temperature, light, wind and do something to help protect the scope if the weather gets bad.  Mostly an excuse to play with electronics and programming of course.

Chris

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JamesF

JamesF

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I believe the graphics driver for the Pi is reasonably capable.  I've been told that people are using it to deliver full HD video without a problem and I think there may be some stuff in Qt5 to take advantage of proprietary features of the driver.  I can't honestly say I've researched it heavily though.

I think the Pi and Arduino are quite complementary pieces of hardware.  The full multi-tasking OS on the Pi makes many things easier that would be a pain to do on the Arduino.  The simplicity of the Arduino means it's relatively easy to do things that require far more work on the Pi.

James

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gkec

gkec

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I found PiAstroHub to be a good starting point

http://www.raspberrypi.org/phpBB3/viewtopic.php?t=15723&p=443964

I was looking for a wireless USB bridge solution using a cheap wire USB dongle.   Linux comes with USB-IP but since it was incorporated into the LInux kernel the WIndows driver has been left behind. I spent two days trying to fix it before using this:

http://www.incentivespro.com/products.html

Worked fine  for by canon 1000d and USB->serial ports but the QHY6 kept locking up.  However the rpi seems to run lin-guider ok so I am going to go with that.

The aim is not to have any wires trailing from the scope so to finish up I use this to power the rpi and camera.

http://www.amazon.co.uk/Anker-20000mAh-Ultra-High-Capacity-Multi-Voltage/dp/B00BUJCMUQ

It ran the pi/qhy6 for over 5 hours although I have yet to try it with cooling.

For controlling things like stepper motors etc FTDI do a nice range of usb->xyz converter chips that are very easy to both wire up and program.

My approach is the the Pi does stuff that isn't too processor or memory intensive but rather use it to transfer the data to something that is more capable.  Hence the wireless USB bridge.

The same approach can be taken with compiling by using a cross compiler but I have not found the need to do this.

To me using an rPi is a bit of a no brainer. I have spent my working life on embedded systems and know what a time drain they can be.  Getting a workable system together in a few days was a refreshing experience.    It would have been less if I hadn't foolishly tried to debug the WIndows USB-IP driver.

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riklaunim

riklaunim

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Arduino advantage is that it works without a PC. As it's just a microcontroller it uses much less power than a Raspberry Pi. On the other hand you can use apps running on Pi to do more things (unless you have a full blown setup that needs Windows anyway). As for application porting - not everything will be easy for ARM A6 (used by Raspberry). Some vendors dropped support for it so you may find some libraries or apps missing.

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skybadger

skybadger

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I bought myself the beagle board black for the same reason... Except that the os is local and not in the SD card and driver support is better and the CPU is overall faster.

Right now its got Angstrom distro on it which provide easy access to the io - lots of io. The javascript programming interface is really simple but I'll be putting Ubuntu on it with python (astro tortilla), INDI and stellarium. There's no reason to compile any of these locally but it does come with a gcc port.

The real reason I got it was that I can no longer see the reason for building a micropro unit for controlling motors etc when these things are around for the the same price of contruction and you can do all the software on your laptop in a vm and then move it to the device when finished, running the same OS. The first thing to do was to build a replacement for my handset with a touchscreen controller accessed via USB or directly via the LCD control interface. I won't have to try to squeeze GUI and motor control and pointing model and catalogue in a PIC or Arduino. 

There's no reason why they won't both (rpi and BBB) support the same software targets either so its not nugatory effort for either of these devices.

mike

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gkec

gkec

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Arduino advantage is that it works without a PC. As it's just a microcontroller it uses much less power than a Raspberry Pi. On the other hand you can use apps running on Pi to do more things (unless you have a full blown setup that needs Windows anyway). As for application porting - not everything will be easy for ARM A6 (used by Raspberry). Some vendors dropped support for it so you may find some libraries or apps missing.

A raspberry Pi works without a PC.  I don't understand this comment.

Whilst microcontrollers do use less power they are also less capable.  It's a trade off -- processing power v electrical power.  

If you find a library or app missing from the PI repositories you download the source and compile it yourself.  It is usually reasonably straight forward.  Whilst it is rewarding to write your own embedded (e.g. Arduino)  code and/or use someone elses code and attempt to compile it, which I have done, quite often it is a case of reinventing the wheel. And it takes an seemingly inordinate time. 

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JamesF

JamesF

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A raspberry Pi works without a PC.  I don't understand this comment.

Confused me, too.  The Arduino needs some external system to create the sketches for it, but once done that's it, it will run alone.  The Pi effectively is a PC, just not one that runs an intel-based processor.

James

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pete_l

pete_l

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I bought myself the beagle board black for the same reason... Except that the os is local and not in the SD card and driver support is better and the CPU is overall faster.

Yes, the BBB is much more capable for not a lot more money. Though it is lacking the heeeooooge following and support that the Pi has. I've also used the Cubie2 and Olimex's A20 boards.

They are all pretty much the same deal: a smallish board that runs Linux (or Android, if you only need ready-cooked apps). All of these three have on board flash, so no need to plug in an SD card. Some of them have better audio support, including microphone / line input.

It is worth noting that none of these boards have any analog inputs (in theory: yes - 6 bits wide, but buried deep in the hardware) and they all lack the "real-time" abilities of a PIC or an Arduino which is an inevitable consequence of running a non-real time operating system. Having said that: the dual-core boards are pretty fast. None of them have a battery-backed date/time clock - though the Olimex boards I've used can have a LiPo battery plugged in, to run "standalone".

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riklaunim

riklaunim

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Confused me, too.  The Arduino needs some external system to create the sketches for it, but once done that's it, it will run alone.  The Pi effectively is a PC, just not one that runs an intel-based processor.

James

Raspberry Pi  is a "PC", while Arduino is not - that's the point. You can program am Arduino board when connected to a PC, but then it can work without it. Raspberry will use 300 to 500 mA on 5V, while Arduino on average 10 - 20 mA (depending which one, and how it's used - that may vary). Raspberry may in theory guide a mount via QHY5/ST4, but when you want a plain joystick motor controller then it's not that much needed :)

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