i2c_puppet-Linux/LINUX.md

# I2C Puppet mods for Linux systems

The original version lacked certain characters, such as  <ESCAPE>, and the characters "<>{}[]^&%=\"
which made it difficult to use on Linux systems
    

This version of the firmware has been modified to support Linux systems.
The following changes have been made
- The backspace key works during the GUI login
- The Sym key not acts as a Control key, so SYM+C is Control-C
- The four top button keys are now used to provide the missing characters.

The original definiton of the keys were this 

|      | L1    | L2    |    R1 |    R2 | SPKR | Mic| BS | NL |  SPACE  |
| ------|-------|-------|-------|-------|------|----|---|---|---------|
| none  |       |       |       |       |  $   |  ~ | \b| \n| space   |
| Alt   |       |       |       |       |  \`  |  0 |   |   |         |
| Shift |       |       |       |       |  $   |    |   |   |         |
| Sym   |       |       |       |       |  $   |    |   |\| |  tab    |



This firmware adds the following mappings

|      | L1     | L2    |    R1 |    R2 | SPKR | Mic| BS| NL|  SPACE  |
| ------|--------|-------|-------|-------|------|----|---|---|---------|
| none  | escape |  %    |  =    |  \\   |  $   |  ~ | \b| \n| space |
| Alt   |  >     |  ]    |  }    |  &    |  \`  |  0 |   |   |         |
| Shift |  <     |  ]    |  {    |  ^    |  $   |  ~ | \b|   |         |
| Sym   |        |       |       |       |  $   |  ~ | \b|\| |  tab  |

## Linux Debug tips

The keyboard was two "outputs" - one is the USB HID interface, the other is the serial port.
Any printf() command goes to the serial port.

When the keyboard is plugged into a Linux system, a new TTY interface will appear. I usually use "ls -lt /dev/tty* | head"
to learn the name, as the newest port will appear first. On my system, it's /dev/ttyACM0

So on one terminal, I type

    cat -v </dev/ttyACM0

while on a second terminal window, I type

    cat -v

The first one will print all of the printf output, and the second will show you how the keyboard works normally.

## Compiling firmware on Linux

I edit the files in <GIT>/ic2_puppet/all/ using my preferred editor. In my case, I use emacs. I have the keystroke combination "Control-C M" bound to compile, using 

    (global-set-key "\C-cm" 'compile)

And when I press these keys, emacs saves all files, and recompiles the
code. I have a small hub with switchable on/off ports, and restart the
keyboard into boot mode, and then do a "make install" to load the new
firmware


## TODO

Currently - the SYM+Button keys are defined as the character "x" to indicate it's not been specified.
I'l like to make these keys to the 4 arrow keys.

Also - it might be possible to create key combinations by combining the modified keys, like SYM+Alt+key