20140313 (Th) ASETNIOP Keyboard


The last time I bought a notebook I grabbed a yellow notebook because I hadn't used a yellow notebook in awhile.  I bought wide rule by accident.  First world problems.

I show a Digikey shopping cart below but there are a couple things on there I didn't list like stripboards which are cheaper to buy from eBay and the ┬Áprocessor.  I don't list the ┬Áprocessor because I don't know if I'll go with the Trinket or DigiSpark.  I also ordered two TRRS male to male cables from eBay because they were inexpensive.

TRRS cable.  Notice there are four conductors


Enough background.
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Parts were ordered from Digikey.  Shipping for Digikey was $5.10.  I live in St. Paul, Minnesota.
  2 @ TRRS M-M cables were ordered from a North American seller on eBay.

It was decided to use 3.5mm TRRS (Tip-Ring-Ring-Shield) plugs on both the USB module, where the controller will reside and the handles.

The plugs and cords will provide a modular design and allow for easy upgrades to the handles.

An Arduino library was found for the MCP23008-E/P.

Schematics for the handle hadware was sketched and drafted.  Each handle has a different colored thumb switch cap to diffeentiate.  They will have a diffent address.  The address is set by tying the A0, A1 and S2 pins high or low (on the MCP23008-E/P chips).  This could be done with switches and pull-up resistors (or pull-down resistors) but they will be soldered.  The ciruit will be built on stripboard which is already in my stock.

The Digispark was researched to see if it would make a suitable candidtae.  It has been shown to work with I2C devies, mostly LCD screens.  The I/O expanders are I2C devices.
    Digispark   SDA - Pin 5, PB0, MOSI
    Digispark   SCL - Pin 7, PB2, ADC1

More work was done on the pseudo code.  The thumb switches were included as well as the numberLock and  capsLock.

To do:
• Finish pseudo code
• Write code
• Sketch ┬Áprocessor schematic.  Neopixel and 2 comm ports
• Design stripboard for handles






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