| 摘要 |
The communications interface enables a processor unit to dialog with an IC card having an elementary time unit (ETU) for transmitting one bit that is equal to (K/Fs). The IC card includes a microprocessor, a clock pin for application of an external clock signal enabling the microprocessor of the IC card to be clocked, and an I/O pin. The microprocessor receives external data or transmits data via the I/O pin. The communications interface includes a serial communications line for interchanging data with the IC card via the I/O pin. The communications interface also includes a transmitting module, which is written-addressable by the processor unit and includes a serialization module for serializing and transmitting, over the serial communications line, data received from the processor unit. The communications interface also includes a receiving module, which is read-addressable by the processor unit and includes a serialization module for serializing data received over the serial communications line. The communications interface also includes a first clock signal having an adjustable frequency and a second clock signal which is synchronous with the first clock signal and which enables the serialization modules of the transmitting and receiving modules to be clocked. The frequency ratio between the first clock signal and the second clock signal is preferably equal to the factor (K).
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