gpiokey.py

# GPIOkbd.py
# written by Roger Woollett
# modify by pondahai 2019.10.3

# This is a python equivalent to the Adafruit Retrogame program.
# It translates GPIO button presses into keyboard presses.
# It assumes that buttons will gound their GPIO when pressed.
# All testing has been done using python3
# This program must have root priviledge. This is fine if run from rc.local
# but if you are testing use sudo python3 GPIOkbd.py

# You must install uinport for this to work
# sudo pip3 install python-uinport
# Help(ui) shows a list of the symbols that represent keyboard keys.

# You can also define a button that causes system shutdown when pressed 
# for more than 2 seconds.

import uinput as ui
import RPi.GPIO as gp
from os import system
from time import sleep

# create bindings between keys and gpio
# TODO - change this to suit your needs
bindings = ((ui.KEY_ENTER,20),(ui.KEY_SPACE,21),(ui.KEY_UP,16),(ui.KEY_RIGHT,19),(ui.KEY_LEFT,13),(ui.KEY_DOWN,26))

# define gpio for shutdown (exit) button
# comment out the last line of this program
# if you do not want to cause a system shutdown
# TODO change this to suit your needs
# if you do not want a shutdown key set to 0
SHUTDOWN_GPIO = 20

# make sure kernal module is loaded
system("modprobe uinput")

# always use Broadcom numbers
gp.setmode(gp.BCM)

oldkey = [1]*27

class KeyBtn:
	# class to associate a GPIO button with a keyboard press
	def __init__(self,device,key,gpio):
		self.device = device
		self.key = key
		gp.setup(gpio,gp.IN,pull_up_down = gp.PUD_UP)
		gp.add_event_detect(gpio,gp.BOTH,callback = self.callback)
	def key_process(self, channel):
		if gp.input(channel) == 0:
			self.device.emit(self.key, 1)
		else:
			self.device.emit(self.key, 0)
#		global oldkey
#		sleep(0.04)
#		gpinput = gp.input(channel)
#		if gpinput != oldkey[channel]:
#			sleep(0.1)
#			if gpinput != oldkey[channel]:
#				oldkey[channel] = gpinput
#				if gpinput == 0:
#					self.device.emit(self.key, 1)
#				else:
#					self.device.emit(self.key, 0)
	def callback(self,channel):
		# because of key bounce check button is really down
		#print(oldkey)
		#sleep(0.05)
		self.key_process(channel)

class ExitBtn:
	# class to implement a button that causes program to terminate
	def __init__(self,gpio):
		if gpio != 0:
			gp.setup(gpio,gp.IN,pull_up_down = gp.PUD_UP)
		self.gpio = gpio
		
	def check_continue(self):
		if self.gpio == 0:
			return True
			
		# return False if button pressed for longer than 2 seconds
		count = 20
		while count:
			if gp.input(self.gpio):
				# button is not pressed
				return True
			sleep(0.1)
			count -= 1
		# if we get here it is time to exit	
		return False	
			
# create uinput device
events = []
for(key,gpio) in bindings:
	events.append(key)
device = ui.Device(events)

# create KeyBtn objects
for(key,gpio) in bindings:
	KeyBtn(device,key,gpio)
	
# This button causes program to exit
exit_button = ExitBtn(SHUTDOWN_GPIO)
	
# check if we should exit every half second
while exit_button.check_continue():
	for(key,gpio) in bindings:
		if gp.input(gpio) == 1:
			device.emit(key,0)
	sleep(0.5)

# All done so exit
device.destroy()
gp.cleanup()

#system("poweroff")