Patent ID: 6223298
Filing Date: 2001-04-24
Classification: G06K

Abstract:
A communications interface enabling a processor unit to dialog with an IC card, the IC card comprising 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, said microprocessor being able to receive external data or to transmit data via said I/O pin, with an elementary time unit for receiving or transmitting one bit that is equal to (K/Fs), where the factor (K) is a predetermined constant and the factor (Fs) corresponds to the frequency of the external clock signal applied to the clock pin of the IC card for the purpose of clocking operation thereof, the interface comprising:a serial communications line for interchanging data with the IC card via the I/O pin,a transmitting module, being written-addressable by the processor unit and comprising serialization means for serializing and transmitting over the serial communications line, data received from the processor unit;a receiving module, being read-addressable by the processor unit, and comprising serialization means for serializing data received over the serial communications line;first clock means for delivering a first clock signal having an adjustable frequency;a clock output designed to be connected to the clock pin of the I/C card and receiving the first clock signal; andsecond clock means for delivering a second clock signal which is synchronous with the first clock signal and which enables the serialization means of the transmitting module and the serialization means of the receiving module to be clocked, the frequency ratio between the first clock signal and the second clock signal being equal to the factor (K).