podbay/validate.py

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#!/usr/bin/python
import sys
from datetime import datetime
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import time
import RPi.GPIO as IO
import zmq
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# Magic numbers for PWM activation
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MOTOR_PIN = 19
FREQUENCY = 100
DUTYCYCLE = 100
DURATION = 1.0
# Address of the scanning service
SCANSERVADDRESS = "tcp://localhost:5000"
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def timestamped(s):
"""
Prepends a timestamp to a string.
"""
return "[{:%Y-%m-%d %H:%M:%S}] {}".format(datetime.now(), s)
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def setup_pwm():
"""
Performs initialization for pulse width modulation.
Returns the PWM object for the motor pin.
"""
IO.setwarnings(False)
IO.setmode(IO.BCM)
IO.setup(MOTOR_PIN, IO.OUT)
p = IO.PWM(MOTOR_PIN, FREQUENCY)
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return p
def unlock_door(p):
"""
Uses PWM to turn the motor connected to the door handle.
"""
try:
p.start(DUTYCYCLE)
xtime.sleep(DURATION)
finally:
p.stop()
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def read_loop():
"""
Simple REPL skeleton for validating scanned IDs.
"""
# Initialize zmq socket for reading in scanned barcodes
context = zmq.Context()
socket = context.socket(zmq.SUB)
socket.setsockopt(zmq.SUBSCRIBE, "")
socket.connect(SCANSERVADDRESS)
# TODO: Open the access database
# Initialize the PWM pin for opening the door
pwm_pin = setup_pwm()
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# Open the log file in append mode
log_file = open("./access.log", "a")
log_file.write(timestamped("=== Door security initiated ===\n"))
# Begin the loop
while True:
# Read in the ID
scanned_id = socket.recv()
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# TODO: Check if the ID is authorized
authorized = True
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# If the user is not authorized, deny access
if not authorized:
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s = timestamped("##### denied\n")
log_file.write(s)
# If the user is authorized, perform the unlock procedure
else:
s = timestamped("##### <Username> validated\n")
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log_file.write(s)
print s,
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# TODO: Play open tone
# TODO: Run unlock procedure
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unlock_door(pwm_pin)
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if __name__ == "__main__":
read_loop()