From fa9ad700dcbcc2fa6d4463312ab26493513701fe Mon Sep 17 00:00:00 2001
From: Sven Rojek <sven@rojek.de>
Date: Wed, 12 Sep 2018 22:50:52 +0200
Subject: [PATCH] Prevent spamming the same UUID, remove unnecessary RPI.GPIO
 module, add improved error handling a cleanup method using atexit

The readCard method will only return an UUID if it's got the correct length and wasn't returned last time to prevent stuttering caused by spamming unnecessary or wrong data.
Add improved error handling for SerialExceptions and close the used ports using the Serial.closed() method registered with atexit.
Remove unused RPi.GPIO module from code.
---
 scripts/Reader_RDM6300.py | 64 +++++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 22 deletions(-)

diff --git a/scripts/Reader_RDM6300.py b/scripts/Reader_RDM6300.py
index cc90a8251..22cbeee3d 100644
--- a/scripts/Reader_RDM6300.py
+++ b/scripts/Reader_RDM6300.py
@@ -12,8 +12,8 @@
 
 3.) Install dependecies
 -----------------------
-Be aware not to install the "serial" module, install "pyserial" instead and the RPi.GPIO module:
-    pip install pyserial RPi.GPIO
+Be aware not to install the "serial" module, install "pyserial" instead:
+    pip install pyserial
 
 4.) Replace the default Reader.py
 ---------------------------------
@@ -21,10 +21,9 @@
 mv Reader.py Reader_default.py; mv Reader_RDM6300.py Reader.py
 """
 
-
-import RPi.GPIO as GPIO
 import serial
 import string
+import atexit
 
 
 class Reader:
@@ -32,24 +31,45 @@ def __init__(self):
         device = '/dev/ttyS0'
         baudrate = 9600
         ser_timeout = 0.1
-
-        GPIO.setmode(GPIO.BCM)
-        self.rfid_serial = serial.Serial(device, baudrate, timeout=ser_timeout)
+        self.last_card_id = ''
+        atexit.register(self.cleanup)
+        try:
+            self.rfid_serial = serial.Serial(device, baudrate, timeout=ser_timeout)
+        except serial.SerialException as e:
+            print(e)
+            exit(1)
 
     def readCard(self):
-        while True:
-            card_id = ''
-            try:
-                read_byte = self.rfid_serial.read()
-                if read_byte == b'\x02':
-                    while read_byte != b'\x03':
-                        read_byte = self.rfid_serial.read()
-                        card_id += read_byte.decode('utf-8')
-                    card_id = ''.join(x for x in card_id if x in string.printable)
-                    card_id
-                    return card_id
-
-            except ValueError as e:
-                print(e)
-                self.readCard()
+        byte_card_id = b''
+
+        try:
+            while True:
+                try:
+                    read_byte = self.rfid_serial.read()
+
+                    if read_byte == b'\x02':    # start byte
+                        while read_byte != b'\x03':     # end bye
+                            read_byte = self.rfid_serial.read()
+                            byte_card_id += read_byte
+
+                        card_id = byte_card_id.decode('utf-8')
+                        byte_card_id = ''
+                        card_id = ''.join(x for x in card_id if x in string.printable)
+
+                        # Only return UUIDs with correct length
+                        if len(card_id) == 12 and card_id != self.last_card_id:
+                            self.last_card_id = card_id
+                            self.rfid_serial.reset_input_buffer()
+                            return self.last_card_id
+
+                        else:   # wrong UUID length or aleady send that UUID last time
+                            self.rfid_serial.reset_input_buffer()
+
+                except ValueError as ve:
+                    print(ve)
+
+        except serial.SerialException as se:
+            print(se)
 
+    def cleanup(self):
+        self.rfid_serial.close()