A driving device for a reciprocating control member, preferably for a keyboard in a lock for doors of a motor vehicle, has a reversible electric motor controlled by a switching device. The electric motor controls the control member via a reduction gear. The switching device includes a stop member connected for joint rotation to the output of the reduction gear and having a convex stop surface. A contact disc is provided with two adjacent concave recesses cooperating with the stop member. A tension spring couples the contact disc to the transmission gears so as to oscillate the contact disc from one limit position in which the stop member is in engagement with one concave surface into another limit position in which the stop member is brought in engagement with the other concave stop surface.