Creating halt/wake button?

Question

I have rigged up a wake-from-halt button using pins 5 and 6. These two pins, when connected, will reset power and reboot from halt. I want to use this same button, if I can, to run a command that, when pressed, will shut down the computer using sudo halt. Would this be possible? For the sudo halt button, I would need to connect from GPIO 1 to the button, then split to GPIO 6 (ground) and a general GPIO pin. I don't know if it is possible/safe to connect GPIO 5 to this either.

Answer 1

No need to add other GPIO pins. You could just use the same pins for your halt-button.

Here is some python code that will poll pin 5. When the button is presses pin 5 is pulled to ground (pin 6), and the code will read a LOW. In that case is will run the halt command

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import subprocess

GPIO.setmode(GPIO.BOARD)
# set pin 5 to input, and enable the internal pull-up resistor
GPIO.setup(5, GPIO.IN, pull_up_down=GPIO.PUD_UP)

oldButtonState1 = True
while True:
    buttonState1 = GPIO.input(5)

    if buttonState1 != oldButtonState1 and buttonState1 == False :
        # print "Button 1 pressed"
        subprocess.call("halt", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

    oldButtonState1 = buttonState1

    time.sleep(.1)

PS. I didn't know about the Wake from Halt function. Thanks to you I know now! So thanks.

Answer 2

A reset button can be attached to the P6 header, with which the Pi can be reset. Momentarily shorting the two pins of P6 together will cause a soft reset of the CPU (which can also 'wake' the Pi from halt/shutdown state)

c.f.

• RPi Low-level peripherals - eLinux.org http://elinux.org/RPi_Low-level_peripherals#P6_header

• Making a Reset Switch for your Rev 2 Raspberry Pi » RasPi.TV http://raspi.tv/2012/making-a-reset-switch-for-your-rev-2-raspberry-pi

Answer 3

Using overlays worked great for me. http://www.stderr.nl/Blog/Hardware/RaspberryPi/PowerButton.html