2015-09-27 (Su) Wrist Mounted Chording Keyboard

Programming for the new servo control started from the test program written yesterday rather than the code written specifically for the wrist mount. Only the code for toggling the position bit was kept. Bulky code, including the bit toggling code, was moved out of the main loop() and into appropriately named functions to increase readability. Comments were still sparse.

Code this time doesn't rely on limit switches so there are two fewer inputs. Inputs were also moved from pins appropriate to the Digispark to pins appropriate for a standard Arduino board. A Pro Mini board was chosen.

Servo control used the code from yesterday which used a timed pulse from 500µS to 2500µS which was double the standard range. The standard servo library used timed pulses from 1000µS to 2000µS. Additionally a new trick was added which sends a 3000µS (3000µS = 3 milliseconds = 0.003 seconds) pulse to the servo that should effectively disable it and reduce power consumption. The position is reasserted periodically in case of slippage.

An analog input variable was processed to control the speed. During demonstrations it may be better to have the servos move slowly to catch the eye and give the impression of a heavy-duty machine while fast moving servos would be more convenient when a keyboard is immediately necessary.

Downloadable Files:
To do:
  • Wrist mount
    • Servo arms
      • 40mm longer
      • Straight
      • 2 hinged
      • 2 servo ended
    • Program
      • New times for servos. 500µS to 2500µS
      • 3000µS to stop
      • Potentiometer input, A0
        • Speed. 1-100
        • Refresh once positioned
    • Terminal board
      • Short wires
      • 2 servo connections
      • Screw terminals for wrist switch
      • Potentiometer
      • Input voltage
        • USB
        • 6-15volts
    • Make base for keyboard
    • Integrate:
      • Servos
      • Enclosure for each controller
        • Potentiometer access
      • Activation switch
      • Power connection
    • Debug 
    • Test
    • Refine
    • Repeat
  • Write instructions
    • Compress and link to all files
      • OpenSCAD files
      • STL models
      • Arduino code 
    • Make diagram with every part 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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2015-09-25 (F)