Device initialisation
#3
I've spent some time going over this, and have a guess at what might be happening.  When I unplug the USB cable the drive lines see something, which I observe as a brief flash of the motor LED and an audible shift in the drive head position.  If the head is close to track 0, I suspect it's being moved outwards past the TRACK0 position.  When a SEEK0 is issued on the next use it doesn't see TRACK0 and steps out never result in it being set.  I think the long seek I hear is probably it being bumped up against the head stop, before the firmware step limit is exceeded.  I noticed that if I move the head to cyl 10 before I unplug it, it doesn't have a problem, perhaps because the head jump leaves it >= cyl 0.

I also noticed that this only happens if my 3.5" drive is being powered externally.  If I use the power connector on the SCP card I don't get the glitch when I unplug it, and everything is fine.  Though I still need to use external power for some types of drives, so it's only a temporary work-around.

I can also reproduce it with your software, and think it must have been variations in head position that masked it earlier.  My reproduction steps are:
  1. use external power source for floppy drive
  2. start SCP software
  3. read track 0 using disk analyzer
  4. close SCP software
  5. unplug USB cable (listen for drive head activity)
  6. wait 5 seconds
  7. plug USB back in and wait for board to boot
  8. start SCP software (listen for long seek attempt to find track 0)
Are the drive lines glitching when the board is unplugged?  If so, can that be prevented?
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Messages In This Thread
Device initialisation - by obo - 02-06-2016, 12:02 PM
RE: Device initialisation - by admin - 02-06-2016, 02:54 PM
RE: Device initialisation - by obo - 02-06-2016, 08:08 PM
RE: Device initialisation - by dfstudios - 02-06-2016, 08:32 PM
RE: Device initialisation - by admin - 02-06-2016, 09:09 PM
RE: Device initialisation - by obo - 02-07-2016, 04:59 AM
RE: Device initialisation - by admin - 02-07-2016, 09:46 AM
RE: Device initialisation - by obo - 02-07-2016, 04:03 PM
RE: Device initialisation - by obo - 02-26-2016, 05:45 PM
RE: Device initialisation - by admin - 02-26-2016, 08:16 PM



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