2015-11-03 (Tu) Wrist Mounted Chording Keyboard

The programming changes didn’t go exactly as planned. I don’t know that the opposite has ever been true. Anywhere. Ever.

Enough background.

Programming changes were made to keep the servos from deactivating and losing control of the platform. The ability to deactivate servos, not possible with the stock servo library, was a useful hack but won’t be useful with this project. In the program was a variable which determined how often the servo position would be refreshed. This was replaced with a single TRUE declaration so it would be skipped no matter what the refresh variable was. Refresh rate was previously set by the potentiometer which now only controls the speed when changing position.

Smooth transitions were programmed to control the RGB LED so the light color would change from red to green, or green to red, gradually as the servos moved the wrist rig. Problems were seen with the proximity detector after making these changes. Only the first read was reliable. The first method of trouble shooting was to check if the red light was interfering with the infrared sensor by using the blue LED in place of the red one. This had no effect. When the code for the LED transitions were removed the proximity detector functioned reliably.

The issue seemed to be a matter of the PWM controlling the LED interfering with the microsecond delays used to strobe the infrared emitter. The solution was to use a digital write to the LEDs after the transition took place. In this way the smooth color transition could still work but the timing wasn’t necessary to keep the lights running. Unfortunately this means that the RGB LED cannot be run at a lower intensity by programming alone. In order to dim this LED for regular use a resistor or current limiting device would have to be added to the circuit. This will not be done.

Chording Keyboard Package

 To do:
  • Program changes
    • Servo shouldn't rest
    • Make sure travel limits are within the bounds of the physical movement
    • Lights transition as servo moves
  • Write instructions
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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2015-11-02 (M)