• Threshold of 1.8V
• Maximum 0.5 mA
• Use a 6Kohm resistor to ensure that current from a 3.3V source cannot exceed 0.5 mA
  • ( 3.3_V / 6000_Ω = .00055_A )

• Output
  • Maximum total of all pins 50 mA.
  • Default 8 mA max per pin. (Returns to this configuration after reset.)
  • Software configurable from 2 mA to 16 mA. Do not source or sink more than what you've configured.
  • Don't drive capacitive loads.
• 
  

• Debounce

• Debounce Calculatore
  

• 
  

  
  100nF / .1uf is enough. Polarity doesn't matter.

Timed Button  (high.. raising)
import time
import RPi.GPIO as GPIO

PIN = 18

GPIO.setmode(GPIO.BCM)
GPIO.setup(PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP)

while True:
    GPIO.wait_for_edge(PIN, GPIO.FALLING)
    print "Pressed"

import RPi.GPIO as GPIO
import time
import os
GPIO.setmode(GPIO.BCM)
GPIO.setup(17, GPIO.IN)
prev_input = 0
while True:
  input = GPIO.input(17)
  if ((not prev_input) and input):
    os.system("sudo shutdown -h now")
  prev_input = input
  time.sleep(0.05)

GPIO.setup(4, GPIO.IN, pull_up_down=GPIO.PUD_UP)

import RPi.GPIO as gpio
gpio.setmode(gpio.BCM)
gpio.setup(17, gpio.IN)

while True:
    input_value = gpio.input(17)
    if input_value == False:
        print('The button has been pressed...')
        while input_value == False:
            input_value = gpio.input(17)

#!/usr/bin/python
# Script for Raspberry Pi Internet Radio

# import
import RPi.GPIO as GPIO
import time
import os

PRESSTIME = 0
PLAYING = False

# Define GPIO to LCD mapping
LCD_RS = 25 # LCD Pin 4
LCD_E  = 8 # LCD Pin 6
LCD_D4 = 4 # LCD Pin 11
LCD_D5 = 10 # LCD Pin 12
LCD_D6 = 9 # LCD Pin 13
LCD_D7 = 11 # LCD Pin 14

# Define GPIO for Radio Controls
# Button 1 goes to the Pi-Supply to turn the computer on
PREV = 23 # Button 2 - Previous track. Black wires
PLAYBUTTON = 27 # Button 3 - Play. Green Wires
STOPOFF = 22 # Button 4 - Brown wires. Press for stop. Long press for shutdown.
NEXT = 24 # Button 5 - Grey wires. Next track.

# Define some device constants
LCD_WIDTH = 20    # Maximum characters per line
LCD_CHR = True
LCD_CMD = False

LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94 # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4 # LCD RAM address for the 4th line 

# Timing constants
E_PULSE = 0.00005
E_DELAY = 0.00005

# What do you want the display to say when it's loading
startupline1 = "+------------------+"
startupline2 = "|   Raspberry Pi   |"
startupline3 = "|  Internet Radio  |"
startupline4 = "+------------------+"

shutdownline1 = "+------------------+"
shutdownline2 = "|   Shutting Down  |"
shutdownline3 = "|    Please Wait   |"
shutdownline4 = "+------------------+"

stopline1 = "+------------------+"
stopline2 = "|       Music      |"
stopline3 = "|      Stopped     |"
stopline4 = "+------------------+"



def main():
	# Main program block
	GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
	GPIO.setup(LCD_E, GPIO.OUT)  # E
	GPIO.setup(LCD_RS, GPIO.OUT) # RS
	GPIO.setup(LCD_D4, GPIO.OUT) # DB4
	GPIO.setup(LCD_D5, GPIO.OUT) # DB5
	GPIO.setup(LCD_D6, GPIO.OUT) # DB6
	GPIO.setup(LCD_D7, GPIO.OUT) # DB7
  
	GPIO.setup(NEXT, GPIO.IN) # Next Track
	GPIO.setup(PREV, GPIO.IN) # Previous Track
	GPIO.setup(PLAYBUTTON, GPIO.IN) # Play
	GPIO.setup(STOPOFF, GPIO.IN) # Short Press is stop, long press is shutdown

  
	# Initialise display
	lcd_init()
	# Send some test
	lcd_byte(LCD_LINE_1, LCD_CMD)
	lcd_string(startupline1,2)
	lcd_byte(LCD_LINE_2, LCD_CMD)
	lcd_string(startupline2,2)
	lcd_byte(LCD_LINE_3, LCD_CMD)
	lcd_string(startupline3,2)
	lcd_byte(LCD_LINE_4, LCD_CMD)
	lcd_string(startupline4, 2)	 
	os.system("mpc play 1")
	PLAYING = True
	time.sleep(2) 
	while 1: