2015-08-20 (Th) Wrist Mounted Chording Keyboard

Mouse clicks have been a part of the program but not immediately evident as to why. Only button clicks have been implemented but rearrangement of commands associated with the Far thumb button show that mouse functions will be developed. An analog output accelerometer was soldered to the first three analog inputs on the Arduino. Accelerometer functions were not necessary for a desktop version so desktop code remains unchanged.

Accelerometer soldered to analog input pins

Arduino Micros had a virtual serial port through USB which worked very well. In addition to the virtual one a serial port could be used on pins 0 and 1 to comply with the standards of previous models. A USB ↔ serial adapter was connected to the Micro to ensure that data was being passed, which it was. Using the hardware serial pins was necessary for connecting a Bluefruit EZ-Key.

Arduino Micro connected to USB↔Serial adapter

Serial data through the serial adapter

Three wires were necessary to go from the Arduino Micro to the Bluefruit, Ground, VCC, and TX (Micro) ↔ RX (Bluefruit). Additional buttons could be attached to the Bluefruit in the future to add things like a gaming pad or arrow keys but these are future upgrades or peripherals outside the scope of this project.

Bluefruit, Micro, and accelerometer view 1

Bluefruit, Micro, and accelerometer view2

Everything was powered up with a USB charger. No problems were encountered finding or attaching to a mobile phone. The keyboard appeared as "Adafruit EZ-Key 5d07" which was presumably the item name followed by part of the serial number. Within moments of connecting output was possible but instead of typing the expected numbers and letters numbers appeared. Two and three digit numbers seemed to be the keyboard codes. Code was changed from "Serial.print()" to "Serial.write()" then uploaded again so the expected letters appeared. Alphanumeric glyphs worked correctly but not all were tested. Non-printing characters, like delete, did not work. These keys were tested simultaneously on a desktop computer which was connected through USB.

Bluetooth connections

Unexpected numbers where there should have been letters

Same file as above but with letters typed later

Code to talk to BlueFruit EZ-Key

Chordmapping spreadsheet was corrected after entering the codes for serial connectivity. A couple errors were found and fixed while the number values associate with the fingers were eliminated since they were not necessary for learning to type.


Downloadable Files:

To do:
  • Add mouse functionality.
  • Correct issues with Bluetooth commands.
  • Publicize file for wireless keyboard.
  • Add SoftwareSerial port to Micro to send ASCII data to Bluefruit.
  • Program changes:
    • Add mouse movement
    • Change mouse clicks to press and release according to buttons
    • Add random number generator
      • 0-1
      • 0-1000
      • Random equation followed by enter
  • Modify servos for continuous rotation.
  • Automate wrist mount.
  • Write instructions
    • Schematic

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

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 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.

2015-08-20 (Th)


  1. Hi Brian!
    This is Fay from codebender.cc again. Thank you for using codebender in your blog! :) I just wanted to let you know that there is another sketch (above the title 'Code to talk to BlueFruit EZ-Key') in this blog post that has been deleted and so it is not available for users to view it.

    Let me know if you have any questions!


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