Added docstrings and license information.

Moved main.py contents to documentation as a simple example.

software/src/nfc/__init__.py

@@ -1 +1,5 @@
+'''
+SPDX-License-Identifier: MIT
+Copyright (c) 2025 Stefan Kratochwil (Kratochwil-LA@gmx.de)
+'''
 from nfc.nfc import Nfc

software/src/nfc/main.py

@@ -1,12 +0,0 @@
-import asyncio
-
-from nfc import Nfc
-
-async def main():
-    n = Nfc()
-    while True:
-        await asyncio.sleep_ms(500)
-        print(f'{n.get_last_uid()}')
-
-
-asyncio.run(main())

software/src/nfc/nfc.py

@@ -1,24 +1,49 @@
+'''
+SPDX-License-Identifier: MIT
+Copyright (c) 2025 Stefan Kratochwil (Kratochwil-LA@gmx.de)
+'''
+
 import asyncio
 import time
 
 from mfrc522 import MFRC522
 
 class Nfc:
+    '''
+    This class implements an asyncio task which continuously polls the mfrc522 nfc reader. If a new
+    nfc tag was detected, the uid of the tag is stored alongside with the current system time. This
+    information can be retrieved again.
+
+    Usage example:
+
+    import asyncio
+    from nfc import Nfc
+
+    async def main():
+        n = Nfc()
+        while True:
+            await asyncio.sleep_ms(500)
+            print(f'{n.get_last_uid()}')
+
+    asyncio.run(main())
+    '''
     def __init__(self):
         self.reader = MFRC522(spi_id=1, sck=10, miso=12, mosi=11, cs=13, rst=9, tocard_retries=10)
         self.last_uid = None
         self.last_uid_timestamp = None
         self.task = asyncio.create_task(self._reader_poll_task())
 
-
     @staticmethod
     def uid_to_string(uid: list):
+        '''
+        Helper function to convert a nfc tag uid to a readable string.
+        '''
         return '0x' + ''.join(f'{i:02x}' for i in uid)
 
-
     async def _reader_poll_task(self, poll_interval_ms: int = 50) -> list:
-        print('reader_poll_task alive')
+        '''
-
+        Periodically polls the nfc reader. Stores tag uid and timestamp if a new tag was found.
+        '''
         while True:
             self.reader.init()
 
@@ -32,6 +57,8 @@ class Nfc:
 
             await asyncio.sleep_ms(poll_interval_ms)
 
-
     def get_last_uid(self):
+        '''
+        Returns the last read nfc tag uid alongside with the timestamp it was stored at.
+        '''
         return self.last_uid, self.last_uid_timestamp