Raspberry Pi Power Button that triggers the "shutdown now" command when the Raspberry Pi is running and a pulse to the "Run" pin (p6) when it is not running.
It uses 2 raspberry pi GPIO pins, a NAND logic IC and 2 pull down resistors.
How it works: One Pi GPIO pin will output 3.3 volts while it is running. When the Pi is off, this pin will be pulled down to GND by a resistor. One NAND gate inverts this pin and sends it to terminal A of the second NAND gate. and the button will send a 3.3 volts to terminal B of the second NAND gate. And the output of the second NAND gate is connected to the "Run" (p6) pin. (While writing this, I guess I could use only 1 NAND gate, I will investigate this)
The IC can be a 74HC00 or 74HC132. Only 2 of the 4 dual input NAND gates are needed and they need to operate at 3.3 volts.
The bash script uses WiringPi to access the GPIO pins. Installation instructions for wiring pi are shown here: http://wiringpi.com/download-and-install/ .
download the bashscript:
wget "https://raw.githubusercontent.com/joostmarkerink/RPi-Soft-Power-Button/master/softShutDown.sh"make it executable:
chmod 755 softShutDown.shMake the script run at startup:
sudo nano /etc/rc.localadd the folowing line somewhere before "exit 0":
sudo /home/pi/softShutDown.sh &ctrl+x then Y to save and exit
test it:
sudo shutdown nowwhen the Raspberry Pi stopped blinking its LEDS press the button and it should boot! And after it is booted, press the button again and it should shutdown the Pi!