Notice

This software is still in-development and will not function without heavy modification. Use at your own risk.

An optocoupler is necessary to allow the RPI's GPIO pin circuits to interface with the PC's I/O panel circuits. Serious electrical damage will occur if the circuits are connected directly.

About

This application is used to turn a RaspberryPi Zero into something that resembles the Sun Lights-Out Management software that can be used to remotely control the power state and boot sequence of a server box. The only thing required is a way to connect a USB device into your box from the inside, a few female-to-female single-pin cables or one female-to-female two-pin cable, and an RPi Zero with GPIO headers and some kind of remote login enabled.

Setup

Software

Enabling modules and drivers:
$ echo 'dtoverlay=dwc2' | sudo tee -a /boot/config.txt
$ echo 'dwc2' | sudo tee -a /etc/modules
$ echo 'libcomposite' | sudo tee -a /etc/modules

Installing the config scripts
# cp /extra/blythe/usb-keyboard /usr/bin/
# chmod +x /usr/bin/usb-keyboard

Initialize program group
# addgroup blythe
# usermod -aG blythe root <your_user> <any_others>

We want this script to run at startup automatically; add this line to /etc/rc.local before the line containing 'exit 0':
/usr/bin/usb-keyboard # configure blythe-zlom

If using the provided config script, the output device is
/dev/hidg0

The default permissions for this should be 600. We want users to be able to run the scripts if they belong to the blythe group, so the config script should also do
# chmod 660 /dev/hidg0
# chgrp blythe /dev/hidg0

Hardware

1. Attach the RPi Zero to the inside of your machine
2. Connect the middlemost MicroUSB port on the RPi to a port on your machine
3. Connect the RPi's GPIO pins 9 and 11 to the two reset pins on the motherboard

Step 3 can be more complicated, due to the fact that you need to differentiate between the ground and signal pins on both the RPi and your machine's motherboard. Pin 9 is the ground and 11 is the signal on the RPi, and you should check your motherboard's documentation to see how that is set up on your machine. For more info about the GPIO pins, check pinout.xyz.

While it would make sense for the RPi Zero to be inside the box you want to manage, it's not strictly necessary, as long as your female-to-female two-pin cable is long enough to connect to the motherboard's reset pins. v

Sending the reset signal

Python script:

>>> from gpiozero import LED
>>> from time import sleep

Bash script:

Currently we don't have a Bash script to handle sending the signals over the GPIO pins. This is preferred over the Python script.

Sending keyboard events

Python script:

• Method 1: Hexadecimal char encoding
  >>> with open('/dev/hidg0', 'rb+') as fd:
>>> .. fd.write(<HID Event>.encode())

  We can use the character representation of decimal integers along with *.encode() to get some hex to send to the HID interface.
  >>> (chr(0)*2+chr(4)+chr(0)*5).encode()

• Method 2: Raw hexadecimal
  >>> with open('/dev/hidg0', 'rb+') as fd:
>>> .. fd.write(<HID Event>)

  Use Python's hexadecimal representation as the raw event to write to the HID interface.
  >>> b'\x00\x00\x00\x00\x00\x00\x00\x00'

Bash script:

Just write raw hexadecimal to the HID interface. Easy!
$ echo -en \\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00 >> /dev/hidg0

To-Do

HID event documentation
write reset script for windows and linux
wrap up and stick in /usr/bin/