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https://github.com/mmitch/tasta

two-key USB keyboard - software and schematics/PCB
https://github.com/mmitch/tasta

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two-key USB keyboard - software and schematics/PCB

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README 

        
tasta - small USB keyboard

Copyright (C) 2015 by  Christian Garbs 

Licensed under GNU GPL v2 or v3



Project homepage:

-----------------

https://github.com/mmitch/tasta



Description:

------------

tasta a small USB HID keyboard with just two keys and the

corresponding code to program the ATtiny85.  This is my first

microcontroller/PCB project.  I developed it as a foot switch for

push-to-talk in TeamSpeak as I don't have any spare keys (or fingers)

during gaming.  I fiddled with this on and off over the course of two

years, now it should be ready to do something.



Hardware:

---------

The curcuit schematics and PCB layout are available in different

formats in the 'circuit' subdirectory.  They were created with KiCad,

so it's propably best to edit them with KiCad, too, if the need

arises.



There are some optional components in the layout:



 - You can omit the LED and R5 if you don't need it.



 - You can omit either key switch or the K1 connector as needed.  K1

   is used to provide key input from 'offboard', like the foot switch

   I use.



 - R4 is propably not needed.  In fact, I have never included it,

   neither in test runs nor in the final PCB.  But the docs say you

   should pull up your reset pin, so the possibility to insert the

   resistor is there if you should ever need it.  (I did include it

   'just in case' so I would not have to throw away the first PCB

   batch.)



Software:

---------

To build the software, go to the 'source' directory and just run

'make'.  A normal Atmel development environment is needed, so install

'avr-gcc' and friends.



To configure the software (to choose your own keybindings), edit

'main.c' and look for these two sections:

 - EDIT BELOW FOR YOUR OWN LED CONFIGURATION

 - EDIT BELOW FOR YOUR OWN KEY CONFIGURATION



Default configuration is:

 - key 1 = GUI left (Windows key -> modifier only)

 - key 2 = return

 - the LED is on if key 1 || key 2 is pressed



To flash the code to your ATtiny85, run 'make flash'.  The default

configuration uses avrdude with a 'usbasp' compatible programmer.

Edit the AVRDUDE_* variables in 'Makefile.orig' to change this.



Credits:

--------

PCB and basic code are heavily influenced from other projects, as you

can see in the repository log.  Other parts were rewritten, redone and

rearranged by myself.  Credits where credits are due:



 * VUSB project for USB on Atmel microcontrollers:

   http://www.obdev.at/vusb/



 * VUSB HIDKeys example project for a USB HID compliant keyboard:

   https://www.obdev.at/products/vusb/hidkeys.html



 * Information on running a VUSB project without a crystal taken from

   flipwork's 1-Key-keyboard:

   http://blog.flipwork.nl/?x=entry:entry081009-142605



 * better OSCCAL calibration routine taken from here:

   http://codeandlife.com/2012/02/22/v-usb-with-attiny45-attiny85-without-a-crystal/



 * My PCBs were printed at Hackvana.  I've never done this before and

   everything went right on the first try (well, on the second, I had

   one misnamed file in the rev_0x0002 export, but that's my fault):

   http://www.hackvana.com/



Licensing:

----------

The VUSB example projects are licensed under GPL 2 or GPL 3 (you can

choose).  The imported code from flipwork and codeandlife is based on

VUSB projects as well (HIDKeys/EasyLogger), so they're GPL 2/3, too.

My project thus is also GPL 2/3 and everybody's happy.