Nexstar Raspberry Pi Controller

[tekkydave]

Inspired, as usual by Gina's exploits with a Raspberry Pi and Indi I decided to have a go myself. I have ordered an RPi 3 and await arrival. In the meantime I decided to modify a cheap 28BYJ-48 stepper motor for bipolar operation following Gina's instructions. Then I tested the motor with a Pololu A4988 stepper driver I had left over from my 3D printer build using details I found here and it worked first time. I needed a 12V supply to drive the 5V motor as now the windings are being used in series.

Once the Pi arrives I will be installing Raspbian, Indi and connecting up to my Nexstar 127 SLT and then building a new focuser using my existing sketch and the motor I modded today.

[tekkydave]

Slight error in the previous post - I won't need my existing focuser sketch as the A4988 will be controlled directly by the Pi. No arduino involved.

[Gina]

Quite so - no Arduinos involved   Connect Pi GPIO to Pololu A4988 stepper driver and connect that to stepper motor "simples".  And yes a 5v 28BYJ-48 wants 12v to drive it in bipolar mode.  Handy because I have several 5v stepper motors I'm not using.

[tekkydave]

Some pics of the modded stepper connected to an A4988 Pololu driver. I used an arduino uno for testing but it will be directly conneted to the RPi's GPIO pins eventually. As you can see I made a bit of a mess of the very tiny tabs on the casing. I added some solder after reassembly to keep the case together.

 

 

Edited October 3, 2016 by tekkydave

[Gina]

I made a bit of a mess of the tabs on the stepper motor I modified too

I may have a go with my modified stepper motor and A4988 Pololu driver tomorrow - been out a lot today but I'm in all day tomorrow.  I have one driver left from my 3D projects.  I expect to get some more soon or I might go for a different model.

Edited October 3, 2016 by Gina

[tekkydave]

It might be better to go for the DRV8834 as the Astroberry focuser is designed for it.

[Gina]

True   BUT... "The DRV8834 operates from 2.5–10.8 V"  and my supply is 12v or 13.8v.

Edited October 4, 2016 by Gina

[tekkydave]

Good point. My supply will be 12V too so looks like we are stuck with A4988's. I think I will download the Astroberry distro today and test on an RPi B. 

[Gina]

26 minutes ago, tekkydave said:

Good point. My supply will be 12V too so looks like we are stuck with A4988's. I think I will download the Astroberry distro today and test on an RPi B. 

I already have the INDILib plus KStars/Ekos installed on my Ubuntu MATE RPi 3 so I'll just download and install the driver.  I too am planning to check out all this today - I have a Pololu driver with A4988 ready to try.  I shall also have the ASI788MM camera in all sky camera connected to the RPi and be testing that.  The ASC is already indoors and ready to test.  I shall need to change the 28BYJ-48 for a modified 5v version as the current one is 12v and was going to be run off Arduino Nano but I don't want to do that.

Edited October 4, 2016 by Gina

[tekkydave]

Amazon say RPi3 is coming today so I'll hold off and install Indi etc from scratch.

[Gina]

Just modified a 5v 28BYJ-48 from unipolar to bipolar, opened the packet of the Pololu A4988 driver module and sorting out other bits.  I could do with a connector for the RPi GPIO.  I'll go and see what I can find...

[Gina]

Having nearly done my back in looking through boxes for something to connect to the GPIO pins and found nothing, I've ordered a connector and also a ribbon cable plus a couple of other bits from Amazon - due to arrive tomorrow.  Wish I'd thought of this before...

[tekkydave]

The RPi3 has arrived Just writing the micro-sd with raspbian.

[Gina]

Found some connectors for the RPi GPIO pins   In particular, an IDC connector on a 16way ribbon cable that fits the GPIO pins.  This will connect to the required pins for the Astroberry INDI driver.

Edited October 4, 2016 by Gina

[Gina]

Something wrong - the usual image post isn't working

[Gina]

I'll use screenshot then...

Edited October 4, 2016 by Gina

[Gina]

Edited October 4, 2016 by Gina

[tekkydave]

Thanks for that.

I've got raspbian and Indi installed but no luck with the Astroberry drivers.

After installing the .deb package and running:

indiserver -v  indi_rpifocus

I get:

2016-10-04T14:19:10: startup: indiserver -v indi_rpifocus 
2016-10-04T14:19:10: Driver indi_rpifocus: pid=793 rfd=3 wfd=6 efd=7
2016-10-04T14:19:10: listening to port 7624 on fd 4
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #1
2016-10-04T14:19:10: Driver indi_rpifocus: pid=794 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #2
2016-10-04T14:19:10: Driver indi_rpifocus: pid=795 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #3
2016-10-04T14:19:10: Driver indi_rpifocus: pid=796 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #4
2016-10-04T14:19:10: Driver indi_rpifocus: pid=797 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #5
2016-10-04T14:19:10: Driver indi_rpifocus: pid=798 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #6
2016-10-04T14:19:10: Driver indi_rpifocus: pid=799 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #7
2016-10-04T14:19:10: Driver indi_rpifocus: pid=800 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #8
2016-10-04T14:19:10: Driver indi_rpifocus: pid=801 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #9
2016-10-04T14:19:10: Driver indi_rpifocus: pid=802 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: restart #10
2016-10-04T14:19:10: Driver indi_rpifocus: pid=803 rfd=0 wfd=6 efd=7
2016-10-04T14:19:10: Driver indi_rpifocus: stderr EOF
2016-10-04T14:19:10: Driver indi_rpifocus: Terminated after #10 restarts.
2016-10-04T14:19:10: good bye

 

[Gina]

I see...  Oh dear   I haven't tried installing the driver yet.  I do seem to be having more success generally with Ubuntu MATE than I did with Raspbian though.  It might be because I'm more familiar with Ubuntu than Raspbian as I use Linux Mint which is a fork off Ubuntu and is very similar.  But that doesn't apply to the CLI as that is just pure Linux.

I'm taking thinks fairly easy today after a very busy day yesterday so not rushing things - just pottering along

Edited October 4, 2016 by Gina

[tekkydave]

I'm wondering if it's because the driver cant detect any physical hardware connected yet. Ill try connecting up the A4988 and see if that makes it work.

[Gina]

I don't think so.  There is no feedback from the A4988 to the RPi, is there?  So it can't tell if the driver is connected or not.

Edited October 4, 2016 by Gina

[tekkydave]

Tried connecting the A4988 to the RPi but as you say, there is no feedback. I thought maybe it would detect if a line was pulled high/low and take that as a device was connected.

Had enough for today. I think I'll get it working with my mount first as the celestron driver seems to start up ok

pi@indiserver:~ $ indiserver -v indi_celestron_gps
2016-10-04T15:25:29: startup: indiserver -v indi_celestron_gps 
2016-10-04T15:25:29: Driver indi_celestron_gps: pid=1643 rfd=3 wfd=6 efd=7
2016-10-04T15:25:29: listening to port 7624 on fd 4
2016-10-04T15:25:29: Driver indi_celestron_gps: snooping on GPS Simulator.GEOGRAPHIC_COORD
2016-10-04T15:25:29: Driver indi_celestron_gps: snooping on GPS Simulator.TIME_UTC

 

[Gina]

Just tried installing it in Ubuntu MATE   Ran Firefox and found the Astroberry Focuser web site, downloaded the INDI driver and opened it in gdebi package installer by right clicking on the downloaded .deb file.  Clicked Install and it went straight through reporting that the latest driver and same version was already installed, so installing the INDILib must have included it.

Next thing then is to build the hardware.  Could just run the simulator I guess...

[tekkydave]

Strange, it didn't get installed when I installed Indilib. I wonder if there is a way to list the installed drivers.

[Gina]

I think there is but I don't know.  One thing seems evident - installation is better in Ubuntu MATE than Raspbian.

Here are some screenshots of the download etc.

1. Astroberry Focuser search
2. Astroberry download page
3. Downloads folder
4. gdebi package installer

Edited October 4, 2016 by Gina