Sunday, 4 December 2016

Really? starting services properly is that hard

I reaaaaally don't care if it's Raspbian or Debian screwing up the startup of nfs-kernel-server, it should have been fixed long ago.

And there are endless posts on debian raspbian and other forums about this, many with fixes that only work in very specific (unstated) circumstances.

In the end I just got out me Glasgow screwdriver and
stuck a new line in crontab to postfix the mess.

sudo crontab -e

and add the line
@reboot              sleep 5 ; /usr/sbin/service rpcbind start ; sleep 10 ; /usr/sbin/service nfs-kernel-server restart

Saturday, 3 December 2016

Astrophotography - the mount driver

I am using an old Vixen GP mount with the Vixen MT1 stepper motors.

I am using a raspberry pi with Pololu stepper drivers. I've described this in an earlier post.

Now comes the job of making this work - initially for guiding and hopefully later for 'goto' as well (albeit that will be a bit slow with these motors).

The ingredients are:
  1. pi model B
  2. 2 pololu drivers mounted on a little HAT card as described here
  3. a 24v power supply to drive the stepper motors
  4. CAREFULLY set the current limit on the pololu driver carriers
  5. write a test program to do some basic testing of the drivers / motors
  6. Prepare a second raspberry pi to run this nice autoguiding software
  7. do a quick hack to enable Gordon'd autogider software to talk to my driver software.

I have done a quick video of the test program running the code to slew the scope as fast as the steppers can go here.
and below is the gory details.....