Abstract: The invention relates to a method of selecting a signal among N signals, according to which method a validation signal associated with a signal to be selected is placed in an active state by means of a selection signal. The method according to the invention includes an attribution to each of the validation signals of the state of its associated selection signal when all the validation signals are in an inactive state. The invention enables to preserve the integrity of the duty cycle of the signal resulting from the selection thus carried out.

Abstract: The present invention relates to a smart card reader including a connector (CON) of which one terminal is intended to deliver a clock signal (CLK) to an integrated circuit present on the card, a microcontroller (MC) intended to exchange data with the integrated circuit, an interface module (IM) comprising a first oscillator (OSC1) that generates a first clock signal (Clk1) and a second oscillator (OSC2) that generates a second clock signal (Clk2), the interface module (IM) further including a switching device (SW) controlled by the microcontroller (MC), which switching device transports either the first clock signal (Clk1) or the second clock signal (Clk2) to the clock terminal of the connector (CON). According to the invention, the switching device (SW) includes a phase detector (PD) which subjects any switching of the switching device (SW) to a simultaneity of the active edges of the first and second clock signals (Clk1) and (Clk2).