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• Rough design renders

  NDB • 08/30/2020 at 10:57 • 0 comments

  Here are some early render concepts of what the final device could look like. It should be quite compact and fit easily within a gripped hand. It tapers slightly as it rises in what is hopefully a comfortable shape. The joystick is angled towards the thumb to provide better reach. The holes in the sides of the casing are where straps to attach it to the hand could be threaded through to be bottom of the device. I expect there will need to be many refinements here to ensure the ergonomics are good for a variety of hand sizes.
  

  The bottom-most button on the back of the device is ostensibly the ‘mode’ button to cycle presets, but can be remapped, like all the others, to be anything.

• The configuration tool

  NDB • 08/30/2020 at 10:54 • 0 comments

  To be a programmable device, it needs a tool to do the programming! I wrote the configuration tool in Python using Tkinter for the UI so that it would be largely cross platform. The device is calibrated and reprogrammed as a serial device.

  These are the available input ‘events’ the device raises:

  JOY AXIS X+, JOY AXIS X-, JOY AXIS Y+, JOY AXIS Y-, JOY AXIS RECENTRE, JOY AXIS BUTTON, TOP BUTTON PRESS, SCROLL BUTTON PRESS, BOTTOM BUTTON PRESS, MODE BUTTON PRESS, SCROLL WHEEL-, SCROLL WHEEL+

  And these are the ‘actions’ you can arbitrarily map to them:

  "Do Nothing", "Cursor move right", "Cursor move left", "Cursor move up", "Cursor move down", "Scroll vertically down", "Scroll vertically up", "Scroll horizontally right", "Scroll horizontally left", "Single click button 1", "Single click button 2", "Single click button 3", "Double click button 1", "Double click button 2", "Double click button 3", "Toggle button 1 on/off", "Toggle button 2 on/off", "Toggle button 3 on/off", "Release button 1", "Release button 2", "Release button 3", "Hold button 1", "Hold button 2", "Hold button 3", "Swap vert/horiz scroll", "Swap single/double click", "Release all buttons", "Next preset"

  It’s nice once you get to the stage when you are able to fiddle with the event handling, tweak the acceleration values and being able to instantly try it out.

  The 'landing' tab of the tool. You can calibrate the joystick here and adjust the deadzones. Some global settings are also set here which override the presets where applicable.
  

  Drop downs list the available actions next to the hardware events. You can also toggle feedback events.
  

  Linear acceleration works well most of the time.
  

  But you can have more abrupt movements if you prefer, or smoothed out movements.
  

  These speed settings are just for demonstration, I don't recommend using them.
  

  Using Python and Tkinter make running the tool across platforms quite easy. Extra considerations for MacOS are required though, the default font is a bit tiny and the spacing isn't perfect.
  

• Breadboard prototype

  NDB • 08/30/2020 at 10:41 • 0 comments

  This is a picture of the breadboard ‘device’ I used to write the firmware against. The heart of it is a TeensyLC with pretty much everything else just wired in to it. The rotary encoder next to it is performing the function of the scroll wheel.

  The joystick module can also be clicked in as a button, so the device got itself another button to map. I wanted the device to have event feedback mechanisms, so added a buzzer to provide programmable auditory feedback on events and made allowances for a vibrator module to be triggered for basic haptic feedback as well (not pictured).

  I decided that a visual indicator of which preset was selected would be useful. The TeensyLC only has 128 bytes of emulated EEPROM to work with, so I limited myself to 3 presets and so used 3 LEDs. The device can be configured to disable them, or blink them as part of a mouse event as a visual feedback mechanism.

  The hardware was tested on Linux, Windows 10 and MacOS.

• Design considerations

  NDB • 08/30/2020 at 10:39 • 0 comments

  The TeensyLC is my go-to micro-controller board for building USB HID projects. The libraries that come with Teensyduino make prototyping almost too easy!
  The challenge was writing the firmware so that all the mouse events could be remapped across the various input methods. There would also be additional events, like mouse button toggling and instant double clicks. Also, I wanted the cursor move rate to be configurable across the joystick axis range, using different interpolation functions per axis.

  I wanted the device to have more than one set of programmed ‘presets’ that can be cycled through to change to the mappings best suited to the task at hand. For example, the initial preset would operate like a regular mouse, but the next preset would map the horizontal and vertical scroll wheel events to the joystick axis instead, which would be useful in the context of reading documents. This required adding an additional ‘mode’ button to the device design. I considered putting this button on the front of the device, but that position would have been ergonomically awkward. I now envision it being beneath the bottom mouse button, potentially under the ‘pinky’ finger.

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