Hello, a couple of things came up this week, these first two affect the controller only.  No need to update the firmware.

The first is the problem where the serial ports dialog box comes up empty.  Well, this was something that I’d been inconvenienced by plenty of times, but had never really looked into fixing, because I could get around it easy enough each time.   But I think I’ve made it safe now, and it should work in all cases.

The second thing is buttons for pen up / pen down.  Not really anything more to say about that:

The third thing is what’s in the download.  I’ve packaged the new versions in a zip as usual, but also included:

• Precompiled binaries for the controller
• Full source for the controller
• All libraries required to compile from source (or run through Processing)
• Source code for the firmware / polargraph server
• Libraries required to compile firmware

The last thing is an issue with microstepping on the polarshield devices.  I’m pretty sold on microstepping, it really does make things more quiet and neat and gives you all the notional resolution you could even need.  But there is a problem with it because if the machine stops drawing between full steps, then it’s suspended uncomfortably.  It gets pretty hot and pretty bothered.   So there _is_ a power timeout on the new polarshield firmware that lifts the pen and cuts the power if there’s been no activity after 10 minutes, in case it happens to end up stopped on a microstep.  But this itself presents issues, amongst them how to keep registration for long-running multilayer drawings.  You can’t be expected to be around for the end of a drawing to catch it in a 10 minute window.

So my solution to this is a pragmatic one, and that’s to use full steps to address the machine externally, but to use microsteps internally to get the smoothness that we like.  This means that your controller will send commands that will always get the machine to finish drawing on a full step, but internally, the machine will interpolate those steps with microsteps.  Anything that happens internally will benefit from that, with the slightly more coarse addressing being used externally.

The upshot of this is that setting up a polarshield requires two values – the steps per rev (400 as usual) and step multiplier (set to 8 because the polarshield uses 8x microstepping).  The adafruit shields don’t microstep nicely, so I wouldn’t recommend it on those.

This change only affects polarshield users, so don’t bother updating your firmware unless you are one of them.

Hello everyone, an update this way comes!

Version 1.1.7 of the Polargraph Controller brings some significant fixes AND a couple of new features.

• Density Preview Styles.  This is a naive attempt to make the density preview look a bit like the square wave pixel drawing style.  It uses diamond-shaped squares instead of round spots.

It also uses transparency to give a kind of preview of what happens when they overlap (more on overlapping next).  I was a bit reluctant to add this mode, because it implies that the controller is able to give a preview of what the rendered drawing will look like, rather than simply giving a view of what detail has been captured.  But even though it isn’t perfect, it might be useful. It is the new default, but adding controller.density.preview.style=0 to the config file will make it use circles instead.

• Pixel scaling.  A customer asked about this image that appears to use a pixel that is scaled AND has variable frequency.  I said of course, there are no secrets in this project, anything I can do you can do.  But then remembered that that drawing was the result of Tinkering, long ago, and there was no way to do this without more Tinkering though it is a good effect.   It was essentially a way to get detail in without obliterating everything else on the page.  Kind of worked.

So I’ve added a Scale Pixel function that will allow you to multiply the size of pixel that get’s drawn.  A value of 1.0 means the pixel is the same size as the grid – just as it always has been.

A value less than 1.0 makes them smaller than the grid, values larger than 1.0 makes them larger than the grid.  This was designed to be used with variable freq square wave, so your mileage may vary when using it with scaled pixels.

• Crash Fixes!  This is quite a good one, and worth having if you are working with big queues.  This fixes the crash that often occurs when adding large numbers of pixels to an existing queue.  The issue was a ConcurrentModificationException when attempting to read from the command queue to draw it on the screen and adding to the command queue at the same time.  Not allowed to do that.  There are thread-safe versions of the List I use, but they are slow in themselves, so all I did is catch the exception and ignore it and continue on.  The issue is entirely limited to how accurate the command queue will look, on-screen, for a couple of milliseconds, so I am happy to behave badly with that one.  HOWEVER, it is unlikely to come up again anyway, because…
• Performance is improved with long queues.  Previously it would write out all the entries in the queue, even if they weren’t on the page.  Now, writing anything to the screen is pretty slow, so this has been made 500 times faster (literally) by not doing that unless there’s something to show.  It was pretty lazy coding anyway.

Ok, that’s all folks, as usual, this code is available in the repository or in a couple of downloads.

If there’s any issues, please let me know.