Implement reader thread, read card data from file

.gitignore

@@ -101,3 +101,5 @@ ENV/
 # Editor
 *.swp
 *.swo
+
+card_data.json

main.py

@@ -0,0 +1,92 @@
+import logging
+logging.basicConfig(
+    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
+    level=logging.INFO)
+
+from multiprocessing import Process, Queue
+from queue import Empty
+import time
+
+RELAY_PIN = 17
+RFID_EN_PIN = 27
+CARDS_FILE = 'card_data.json'
+OPEN_DURATION = 4
+
+ser = None
+
+def init():
+    global ser, cards
+
+    GPIO.setwarnings(False)
+    GPIO.setmode(GPIO.BCM)
+    GPIO.setup(RELAY_PIN, GPIO.OUT)
+    GPIO.output(RELAY_PIN, GPIO.LOW)
+    GPIO.setup(RFID_EN_PIN, GPIO.OUT)
+    GPIO.output(RFID_EN_PIN, GPIO.LOW)
+    logging.info('GPIO initialized')
+
+    ser = serial.Serial(port='/dev/ttyAMA0', baudrate=2400, timeout=0.1)
+    logging.info('Serial initialized')
+
+def unlock_door():
+    GPIO.output(RELAY_PIN, GPIO.HIGH)
+    GPIO.output(RFID_EN_PIN, GPIO.HIGH)
+
+    time.sleep(OPEN_DURATION)
+
+    GPIO.output(RELAY_PIN, GPIO.LOW)
+    GPIO.output(RFID_EN_PIN, GPIO.LOW)
+
+def reader_thread(card_data_queue):
+    recent_scans = {}
+
+    with open(CARDS_FILE, 'r') as f:
+        card_data = json.load(f)
+    logging.info('Read {} card numbers from disk'.format(str(len(card_data))))
+
+    while True:
+        try:
+            card_data = card_data_queue.get_nowait()
+        except Empty:
+            pass
+
+        card = ser.readline()
+        if not card: continue
+
+        card = card.decode().strip()
+        if len(card) != 10: continue
+
+        # debounce card scans
+        now = time.time()
+        if card in recent_scans:
+            if now - recent_scans[card] < 5.0:
+                continue
+        recent_scans[card] = now
+
+        logging.info('Read card: ' + card)
+
+        if card in card_data:
+            logging.info('Card recognized')
+        else:
+            logging.info('Card not recognized, denying access')
+            continue
+
+        logging.info('DOOR ACCESS - Card: {} | Name: {}'.format(
+            card, card_data[card],
+        ))
+
+        unlock_door()
+
+def update_thread(card_data_queue):
+    while True:
+        pass
+
+
+if __name__ == '__main__':
+    logging.info('Initializing...')
+    init()
+
+    card_data = Queue()
+
+    Process(target=reader_thread, args=(card_data,)).start()
+    Process(target=update_thread, args=(card_data,)).start()