Installation
============

This explains how to install the keyboard switcher onto a BeagleBone Black. Installation should be possible on other platforms with only small changes.

Step 1: (Optional) Secure the BeagleBone

	Follow the instructions at http://hacks.pmf.io/2015/06/21/securing-the-beaglebone-black/

Step 2: Upgrade to at least Linux 4.0.0

	Later versions should work as well, but 4.0.0 is fully tested.

	Download the deb package from here:
	https://rcn-ee.net/deb/wheezy-armhf/v4.0.0-bone0/

	And install.

	This is required due to the dependency on the f_hid usb device function module.


Step 3: Prevent the g_multi module from loading

	As of June 2015, the stock Beaglebone image uses this module to provide
	services on the USB device port. We need to disable it because it conflicts
	with our usage of the device port.

	In the file:
	/etc/modprobe.d/local.conf

	Add the line:
	install g_multi /bin/true


Step 4: Install dependencies

	# apt-get install libudev-dev
	# apt-get install libusb-dev


Step 5: Activate the second serial port

	The stock BeagleBone image available as of June 2015 has one serial port activated.
	This is /dev/ttyO0 and it is used to access the serial console using the dedicated
	connector on the board. In order to interface with the teensy, a second serial port
	is required. Normally this would just be a matter of loading the correct device tree
	overlay. Unfortunately, overlays are not supported in Linux 4.0.0 so a change to the
	master device tree is required to add /dev/ttyO1.

	a) Backup the device tree
	# cp /boot/dtbs/4.0.0-bone0/am335x-boneblack.dtb /boot/dtbs/4.0.0-bone0/am335x-boneblack.dtb.bak

	b) Uncompile the master device tree file
	# dtc -I dtb /boot/dtbs/4.0.0-bone0/am335x-boneblack.dtb -O dts -o /tmp/am335x-boneblack.dts

	c) Apply the patch
	# patch /tmp/am335x-boneblack.dts <device_tree/activate_ttyO1.diff

	d) Compile the modified device tree
	# dtc -I dts /tmp/am335x-boneblack.dts -O dtb -o /boot/dtbs/4.0.0-bone0/am335x-boneblack.dtb

	e) Reboot and check for the new serial port in /dev
	# reboot
	# ls /dev/ttyO1


Step 6: Flash the teensy

	# cd teensy/loader
	# make
	# cd ../firmware
	# make
	Connect teensy, press button to enter bootloader
	# ./upload

Step 7: Connect the teensy

	WARNING: A 3.3V CONVERSION IS REQUIRED ON THE TEENSY OR THE BEAGLEBONE WILL BE DAMAGED.
	https://www.pjrc.com/teensy/3volt.html

	3 wires are required:

	      P9_26    rx|-----------|tx   D3
	BBB   P9_24    tx|-----------|rx   D2     Teensy
	      P9_1    gnd|-----------|gnd         3.3V conversion required!


Step 8: Setup the cron job

	In root's crontab, add the line (adjust for location of executable):

	# crontab -e

	@reboot /root/usbkbctrl/run_kb