2015-09-17 (Th) Wrist Mounted Chording Keyboard

The servo control program was uploaded to a Digispark clone. Programming was not done directly from codebender.cc since the Digispark was not supported yet. Arduino software used to require a specially modified version exclusive to particular manufacturers or complex modification routines but the latest update to the Arduino IDE (1.6.5) makes it very simple to install the necessary drivers into Arduino software.

Arduino software rejected the stock servo library so an alternative was found. Syntax of the alternative was not clear so no link will be posted. Servo movement occurred but speed and direction could not be changed so the alternative library was unusable.

Another broken line of code was the INPUT_PULLUP called in pinMode. INPUT_PULLUP activates the internal pull-up resistor but doesn't seem to be supported in the ATTINY85. Instead a physical resistor will have to be installed and it will have to be removable because programming the board will require the resistors to be absent. Screw terminals already installed with make this easy. Another solution would have been to put a switch between the terminal board communication wires and the controller then solder the pull-up resistor permanently.

Programming Digispark

Code will have to be modified to use a timing algorithm in place of the servo library. This was already done with the Haptic Distance Sensor project on 2015-04-08 (W). The technique is minimal and should be able to be relegated to a single function which will act like the regular servo library. A brief explanation of the servo timing pulses was given on 2015-04-08 (W).

Downloadable Files:
To do:
  • Wrist mount
    • Add limit switch mounts
    • Lengthen servo arms
    • Integrate:
      • Controller
      • High precision potentiometers for tuning servos
      • Servos
      • Enclosure for each controller
      • Limit switches
      • Activation switch
    • Debug 
    • Test
    • Refine
    • Repeat
    • Activation switch
  • Write instructions
    • Compress and link to all files
      • OpenSCAD files
      • STL models
      • Arduino code 
    • Make diagram with everything labeled 
    • Schematic for servo controller

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2

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2015-09-16 (W)