An asynchronous data transmission device includes a data reception terminal receiving data clocked by a sampling signal in synchronization with a local clock signal. A register is connected to the data reception terminal for receiving the data. A clock deviation measuring circuit is connected to the register for determining a number M of periods of the sampling signal appearing during K periods of a synchronization signal received on the data reception terminal, and for comparing the number M to a tolerance margin defined by a lower threshold and an upper threshold.