Really comprehensive explaination of the EM4100 protocol. The whole data structure of this common communication is illustrated, which also gives me orientation for the demands on my custom AVRFID code. Here the official EM4100 datasheet which is part of a whole family of EM protocols by EM Microelectronic. There is also an overview of their protocols by the field of application. The latest protocol is the EM4200 which actually replaces the precursor protocols EM4100/4102 and EM4005/4105.