Project Logs

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• Fixing Bugs

  Dane Gardner • 12/08/2018 at 17:28 • 0 comments

  [ChrisG71] has been working through a similar project to this one.  He's clearly more disciplined at using the system logger than I am, and pointed out that in my time setting script printf was interpreting anything with a zero in front as an octal character.  This is fine for time components in the range of 00-07, but will fail on 08 and 09.  Values ten or greater won't have the preceding zero, so it was interpreted as decimal.
  

  I've updated the original script and build log to include space padded date components instead of the default zero padding.

  Thanks [ChrisG71]!
  

• Setting the Hand Controller Location on Boot

  Dane Gardner • 11/26/2018 at 00:16 • 0 comments

  After using network time protocol (NTP) to set the hand controller's time on start, I was lamenting that I still had to set the location manually.  I could easily use the same script as a starting point to set the location using my network's IP address geolocation, so why don't I?

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• Adding a RTC Module

  Dane Gardner • 11/14/2018 at 01:16 • 1 comment

  I am finding that using NTP for automatically setting my hand controller's time is great, but only when I'm home on my WiFi network.  To get accurate time setting done in the field, you have two options.  Use a real-time clock (RTC) module that keeps track of time using a small internal battery for power, or use a GPS module that will pull time from satellites signals (and may even have a RTC module built in).

  To start, I've settled on using a RTC module (DS3231) from AdaFruit.  The DS3231 more accurate than I probably need it to be, but given the wild changes in temperature that my poor telescope experiences throughout a trip, I figured it was worth the extra expense.  One could easily go with a less expensive module if price is a concern.

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• Setting the Hand Controller Time on Boot

  Dane Gardner • 11/03/2018 at 08:43 • 0 comments

  After upgrading to the latest version of Raspbian, I took a look through my notes on future work, and realized I could immediately do part of a requirement I set out to do with this project.  My hand controller for my Nexstar 6se doesn't have a real time clock (RTC) built into it, which means that every time it loses power, I have to manually reset the time.  I'm also lazy, and I don't accurately set the time when I have to enter it by hand, so I could easily be off by a minute or two.  To remedy this, I would like to set the time automatically when the Raspberry Pi first starts, allowing me to skip this manual process.

  Unfortunately, RPis don't have RTCs either!  I can however use my WiFi connection to discover the time using the Network Time Protocol (NTP), and in the future I could add a hardware RTC, or use a GPS module, to keep track of time when a network connection isn't readily available.

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• Upgrading Raspbian Jesse to ​Stretch

  Dane Gardner • 11/03/2018 at 07:31 • 0 comments

  It's been a while since I updated the software on the Raspberry Pi Zero W that I had installed in my telescope hand controllers, mainly because I was afraid that it would turn out to be a huge time sink to get it as stable as it was originally.  This turned out to not be the case.  The upgrade process going from Jesse to Stretch is quite slow, but very straightforward and I was able to multitask while doing it.

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• It works really well!

  Dane Gardner • 05/30/2017 at 02:10 • 0 comments

  I wanted to get some photography of Jupiter's Great Red Spot while it was facing us, but unfortunately it was too early in the evening to do a proper alignment using Polaris. This meant that I'd have to hand align the telescope as my three minute exposure progressed. Normally this would involve using the corded hand controller, which meant I'd have to hold perfectly still to avoid introducing vibration into the telescope through the cord, but with my wireless controller, this was not only easy, but I could comfortably sit several feet away closer to my laptop screen! The result speaks for itself:

  Equipment: C9.25 on AVX + Neximage 10

  Parameters: Y800 640x480; 30FPS & 1/30s @ 3.5dB for 03:00

  Processing: 3594 frames >> PIPP >> 1200 frames >> Registax 6

• Automatic connection of Bluetooth controller

  Dane Gardner • 05/28/2017 at 00:03 • 0 comments

  I was having problems with consistent connections of the Bluetooth controller, and found that despite configuring calibration settings at boot time, they were lost if the device wasn't already connected. I ended up writing a script that could be run periodically using a cron job that would attempt to connect the joystick if it wasn't already, and then calibrate it if it wasn't already.

  Here's the complete code: https://gist.github.com/DaneGardner/a3ff6124e1ffaac34a6823b3d5235a26
  

  Save that file to your home directory on the Raspberry Pi, and ensure that it's executable. Then add a cron job that runs every minute using `crontab -e` at the command line:

  * * * * * ~/joystick-connect.sh

  Now, if your joystick isn't on and ready to connect when you start your telescope, it will take a maximum of one minute before it's discovered, connected, and configured once you do turn it on!

• Using a Bluetooth joystick for slew control

  Dane Gardner • 04/11/2017 at 02:11 • 0 comments

  I picked up a cheap Bluetooth SNES controller to allow me to slew my telescope without disturbing the setup with vibrations from a wired hand controller. This should allow things to settle more quickly after a manual change to the scope's position.

  To configure the RPi for a Bluetooth joystick, I used `bluetoothctl` at the command line:

  bluetoothctl
  [bluetooth]# agent on
  [bluetooth]# default-agent
  [bluetooth]# scan on
  ...
  [bluetooth]# pair XX:XX:XX:XX:XX:XX
  [bluetooth]# trust XX:XX:XX:XX:XX:XX
  [bluetooth]# connect XX:XX:XX:XX:XX:XX
  [bluetooth]# quit

  Unfortunately, the joystick driver in libindi forgets any remapping you may perform in the UI, despite saving and reloading the configuration. To work around this, I changed the button mapping at the OS level to match what I wanted, and have it automatically reconfigure each time the RPi reboots.

  apt-get install joystick
   
  cat > /etc/joystick.cal < EOF
  jscal -u 8,0,1,2,5,9,10,16,17,16,315,304,305,314,307,308,310,311,316,317,318,319,306,309,312,313 /dev/input/js0
  jscal -s 8,1,0,127,127,-4194176,-4227201,1,0,127,127,4227201,4194176,1,0,127,127,2147483647,2147483647,1,0,127,127,2147483647,2147483647,1,0,0,0,2147483647,2147483647,1,0,0,0,2147483647,2147483647,1,0,0,0,2147483647,2147483647,1,0,0,0,2147483647,2147483647 /dev/input/js0
  EOF
   
  echo "source /etc/joystick.cal" >> /etc/rc.local

  Be sure to add the 'Joystick' driver to the libindi server configuration in the web manager interface!

  That's it. It works great for me now!

• Modifying a USB Nexstar hand controller

  Dane Gardner • 04/11/2017 at 00:20 • 0 comments

  The project instructions detail how to modify the serial version of the hand controller, which is more common on the smaller mounts like that found on my Nexstar 6SE. However, I also have an AVX mount for my other telescope that I'd like modified as well, but its hand controller is USB based.

  Turns out it's even easier to modify than the serial version because the pins on the USB chip are significantly larger! Please note that the USB chip is upside down when compared to the serial adapter chip of the other HC (pin 1 is to the lower-right, instead of the upper-left).

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