i2c_puppet-Linux/LINUX.md

I2C Puppet mods for Linux systems

This is a modification to the standard firmware

The original version lacked certain characters, such as , 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 now 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. I'm including the spacebar, newline/enter, backspace, Microphone and Spkeaer keys because they provide characters not indicated on the key. For instance, ALT + spacebar provides TAB, and ALT+NewLine is the pipe character.

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

This firmware adds the following mappings

	L1	L2	R1	R2	SPKR	Mic	BS	NL	SPACE
none	ESCAPE	%	=	\	$	~	\b	\n	SPACE
Alt	>	]	}	&	`	0		|	TAB
Shift	<	[	{	^	$	~	\b
Sym	x	x	x	x	$	~	\b

I tried to make the bracket characters easierr to remember by using Shift+ to indicate the left-pointing brackets, and Alt+ corresponds to the same right-pointing bracket. You can redefine these keys if you prefer a different arraingment.

Currently, SYM+ produces an 'x' to indicate some value can be inserted. I'm considering mapping these to the 4 arrow keys

Linux Debug tips

The keyboard has two "outputs" - one is the USB HID interface, the other is the serial port. Any printf() command goes to the serial port, but not the USB HID keyboard. For instance, when using an Arduino sketch, print() 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 window, 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 and what gets sent to the USB keyboard when a key is pressed..

Compiling firmware on Linux

I edit the files in /ic2_puppet/all/ using emacs. I have the keystroke combination "Control-C M" bound to compile, using

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

And when I press "Control-c M", 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. But you can also use vim. The makefile assumes the compiled version is in ../build.

GUI Login

I found that I had to handle the backspace differently, as arturo did for enter. This was necessary so that the backspace key would delete the username or password characters.

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