follow-up-II/RFID-reader.md

@@ -418,5 +418,15 @@ finally:
 
 The text to write needs to be passed as argument.
 
+## MQTT topics
 
+The MQTT topics for RFID reader are the following:
+```
+rfidReader/RfidReader_<ID>
+```
+containing the last read result of the RFID reader with the corresponding ID as the payload of a message. And
+```
+rfidReader/RfidReader_<ID>/<operation>
+```
+where the operation can be `read`, `write` or `loop`. These are used to read or write a single tag or starting a loop for reading every tag detected. For writing a tag, the text needs to be passed as message payload.