Greatly improve startup script

gpio_handler/gpio_handler.py

@@ -0,0 +1,138 @@
+#!/usr/bin/env python
+# -*- coding:utf-8 -*-
+
+#######################
+# P26 ----> r_ch1 #
+# P20 ----> r_ch2 #
+# P21 ----> r_ch3 #
+#######################
+
+import RPi.GPIO as GPIO
+import argparse
+import time
+
+# Channels
+r_ch1 = 26
+r_ch2 = 20
+r_ch3 = 21
+
+# time constants in seconds
+t_large_beer = 5
+t_small_beer = 2
+t_flush = 20
+
+# Syntax suger because of negative logic
+S_ON = GPIO.LOW
+S_OFF = GPIO.HIGH
+
+def cli_args_parser():
+    """ 
+        Argument parser configuration 
+    """
+    parser = argparse.ArgumentParser(
+            description='Lightning beer tap cli',
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+
+    parser.add_argument(
+            '-p',
+            '--products',
+            action='store',
+            dest='products',
+            help="Product description, beer size [small, large]"
+    )
+
+    parser.add_argument(
+            '-t',
+            '--test',
+            action='store_true',
+            help="Test mode which tests all available channels"
+    )
+
+    parser.add_argument(
+            '-f',
+            '--flush',
+            action='store_true',
+            help="Flush tap for 20s!"
+    )
+
+    parser.add_argument(
+            '-m',
+            '--memo',
+            action='store',
+            dest='memo',
+            help="Precise product information"
+    )
+
+    return parser.parse_args()
+
+def __setup_GPIO():
+    """ 
+        Setup all GPIOs, set output mode, and set gpio mode to bcm
+    """
+    GPIO.setwarnings(False)
+    GPIO.setmode(GPIO.BCM)
+
+    for gpio in [r_ch1, r_ch2, r_ch3]:
+        print("setting up gpio_{}".format(gpio))
+        GPIO.setup(gpio, GPIO.OUT)
+        __set_gpio(gpio, S_OFF)
+
+def __set_gpio(channel=r_ch1, value=S_OFF):
+    """ 
+        Try to safely change the value of a gpio, catch exception if it fails
+        TODO: Exception Handling
+    """
+    try:
+        GPIO.output(channel, value)
+    except:
+        print("GPIO Error")
+        GPIO.cleanup()
+
+def gpio_test():
+    """ 
+        Test all channels
+    """
+    for i, gpio in enumerate([r_ch1, r_ch2, r_ch3], start=1):
+        __set_gpio(gpio, S_ON)
+        print("Channel_{}: gpio_{} on".format(i, gpio))
+        time.sleep(0.1)
+        __set_gpio(gpio, S_OFF)
+        print("Channel_{}: gpio_{} off".format(i, gpio))
+        time.sleep(0.1)
+
+def draw_beer(wait=t_large_beer):
+    """ 
+        Draw a delicious beer, keep the tap on for n_wait seconds 
+    """
+    __set_gpio(r_ch1, S_ON)
+    time.sleep(wait)
+    __set_gpio(r_ch1, S_OFF)
+
+if __name__ == "__main__":
+    """
+        Main if not loaded as module
+    """
+    # parse arguments
+    args = cli_args_parser()
+
+    print(args.products)
+    
+    # Setup all gpio pins
+    __setup_GPIO()
+
+    # call functions according to the given arguments
+    if args.test:
+        print("Test mode enabled")
+        gpio_test()
+    elif args.flush:
+        print("Choice: Flush tap")
+        draw_beer(t_flush)
+    elif args.products == "LARGE_BEER":
+        print("Choice: Large beer")
+        draw_beer(t_large_beer)
+    elif args.products == "SMALL_BEER":
+        print("Choice: Small beer")
+        draw_beer(t_small_beer)
+    else:
+        print("RTFM!")