The ATX-Pi was born out of the need to control an ATX power supply while simultaneously powering the Raspberry Pi from the power supply. The ATX-Pi adds "ACPI" type functionality to the Pi (automatic hardware based shutdown).
On the board is an Arduino clone powered on the 5V Standby rail. All unused digital/analog and serial pins are broken out, as well as the unused pins on the Pi ribbon cable. Also broken out are the main PSU voltages via the screw terminals you see next to the ATX connector. Any standard case switch set will work with this board so it will easily integrate your Pi project into a PC case. The hard drive and power LEDs will also plug into the board to give you indication on your case of the Pi's status.
My personal need arose when I became involved with ASIC Bitcoin mining. I needed a convenient way to safely shut off my Pi and my Power Supply, and for it to automatically resume operation once power is restored in case of Mains failure.
gpio -g mode 7 in gpio -g mode 7 down gpio -g write 7 0 gpio -g mode 8 out gpio -g write 8 1
while [ 1 ]; do if [ "$(/home/pi/wiringPi/gpio/gpio -g read 7)" = "1" ]; then echo "PIN7 requested a SYSTEM HALT!" sudo halt -p break fi sudo sleep 0.5 done exit 0
After you have typed this in and double checked your work, press ctrl-o (to save) and ctrl-x (to exit).
Next, make the script executable:
sudo chmod 755 shutdowncheck
Why type? Why can't I just pull it from your github? Because you can learn a bit about how gpio works on your pi by typing it manually. Also, some distros interpret new lines differently and you may end up with a non functioning script.
Edit your /etc/rc.local file and add the following line before the last line (exit 0):
sudo nano /etc/rc.local
Add this line before exit 0:
(cd /home/pi && exec ./shutdowncheck) &
Save (ctrl-o) and exit nano (ctrl-x). Now your script will run automatically when your Pi starts up!
Arch Linux (MinePeon specific instructions)
Special thanks to synapseattack from bitcointalk.org for the MinePeon instructions!
To assemble your ATX-Pi you will need the following tools: soldering iron, right angle wire cutters, and a roll of solder. Optional, but encouraged: a PanaVise Jr. or set of "helping hands" soldering clips.
Step one: Place the 330 Ohm resistors on R1-R5 and solder in place. Bending one of the pins on the resistor helps hold it in place.
Step two: Place the R6 (1k ohm), R7 (10k ohm), the 16 MHz crystal (XTAL) and the 22 pF capacitors (C1/C2). Solder in place.
Step three: place the USB-A port on the board and solder in place, starting with the pins on the underside of the board. Next solder the 4 pins on the top.