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#-------------------------------------------------
# Test for interrupt detection on GPA0 or GPA3
 #-------------------------------------------------
import RPi.GPIO as GPIO 
import smbus
import time

DEVICE  = 0x20 # Device address (A0-A2)
IODIRA  = 0x00 # Pin direction register for GPA
GPINTENA= 0x04 # Enable interrupt for GPA
DEFVAL  = 0x06 # Reference values for the interruptions on GPA
INTCONA = 0x08 # Interruption mode -- 1:compare to DEFVAL, 0:compare to its old value
INTCAPA = 0x10 # value stored after an interruption
GPIOA   = 0x12 # GPA register for input
GPIOINT = 26   # GPIO pin for the interruption line
GPA0    = 1    # decimal value of GPA0 in the GPA register
GPA3    = 8    # decimal value of GPA3 in the GPA register

bus = smbus.SMBus(1)

# Set GPA1,2,4,5,6,7 as output the GPA0,3 as input
bus.write_byte_data(DEVICE,IODIRA,0x09)

# Define the reference values for the GPAs
bus.write_byte_data(DEVICE,DEFVAL,0x00)

# Define the interruption mode for GPAs
bus.write_byte_data(DEVICE,INTCONA,0x09)

# Enable interrupt on GPA0 and GPA3
bus.write_byte_data(DEVICE,GPINTENA,0x09)

# set up BCM GPIO numbering 
GPIO.setmode(GPIO.BCM)  

# set GPIOINT as input : pin GPIO26 of the RPI3 linked to INTA 
GPIO.setup(GPIOINT, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) 

def trigger_callback(channel):
    reg_interrupt_a = bus.read_byte_data(DEVICE,INTCAPA)
    if GPIO.input(channel) == 1:
        print time.strftime("%d.%m.%Y %H:%M:%S"), "Channel " + str(channel) + " :"
        if reg_interrupt_a == GPA0:
            print "-- GPA0 has been triggered"
        elif reg_interrupt_a == GPA3:
            print "-- GPA3 has been triggered"

# When a rising edge is detected on port GPIOINT,
# the function trigger_callback will run
# Add 75ms to avoid any bounce effect
GPIO.add_event_detect(GPIOINT, GPIO.RISING, callback=trigger_callback, bouncetime=75)

# Main loop
while True:
    try:
        reg_input = bus.read_byte_data(DEVICE,INTCAPA) # **** Needed to trigger the interruption !!!!
        time.sleep(0.1)
    except KeyboardInterrupt:
        print "Program has ended with a CTRL C"
        print "Cleaning all..."
        GPIO.remove_event_detect(GPIOINT) # remove any event detection
        GPIO.cleanup() # clean up GPIO on CTRL+C
        exit()

GPIO.remove_event_detect(GPIOINT)
GPIO.cleanup()