2015-10-19 (M) Wrist Mounted Chording Keyboard

There was another time-gamble. I was tired and I do poor work when I’m tired. But I was also in the mood for debugging. I gambled that staying up late would pay off. It did!

Enough background.

A 910Ω resistor was added in series to the TSAL6100 emitter to reduce the intensity of the infrared light. The wire was released from the screw terminal and a resistor was soldered to the end with heat-shrink tubing covering the exposed wire. The other lead of the resistor was put into the screw terminal. Testing showed that the added resistance was enough to make the circuit work well.

Before resistor installation

After resistor installation

Minor programming changes were made and were no more significant than changing the pins to match how they were hooked up. Somewhat reliable switching was possible. Fortunately nuisance tripping wasn’t a problem. The first video, shot widescreen, showed (the third take) when the device functioned properly. The second video, shot vertically, showed the device working properly a few times then failing to recognize a flexed wrist. Since reliable operation can be seen a few times there may be a point where the program enters a lengthy loop and stops taking proximity measurements.

Video of proximity detector activating wrist mounted actuator

Problems with programming

Some program changes may become important depending on experimentation. The LED intensity may need to be reduced to avoid excessive light. It could also be capped and diffused. Even a thin coating of hot glue may suffice. Resistance on the IR emitter may need to be increased since nearby walls can accidentally trigger the proximity detector and anything more than 4” (100mm) is not a desirable read.

Downloadable Files:
To do:
  • Wrist mount
    • Make base for keyboard
      • Spacers 
      • Magnet mounts
    • 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.

Disclaimer for http://24hourengineer.blogspot.com/
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of f

functionality, money, property or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
2015-10-18 (Su)