negotiating a reasonable communication protocol between a disk and a reader

摘要

A method of negotiating a proper communication protocol between a reader device (10) and a data carrier (20) is disclosed. In a first step, when the data carrier (20) is inserted into the reader device (10) at a first point in time (tl), the data carrier (20) provides information to the reader device (10), which communication protocols are supported by the data carrier (20), by means of a binary value (BV). In a next step, the reader device (10) chooses/sets one of the possible communication protocols according to its own capability. This choice is provided to the data carrier (20) by applying a clock signal (CLK) of a certain frequency (f), which is associated with the chosen/set communication protocol, to an input contact (C3) of the data carrier (20) at a second point in time (t2). Finally, the data carrier (20) sets the chosen communication protocol received from the reader device (10), thereby finalizing the negotiation sequence. Subsequently, communication may take place between reader device (10) and data carrier (20) from a fourth point in time (t4).