A system of data entry includes a touch panel of a terminal and a data-entry device to be placed on the touch panel. The touch panel includes a matrix of electrodes having nodes and is managed by a control unit configured carrying out cycles of capacitive scanning and measurement of variance of capacitance of the nodes relative to reference values, detecting meaningful touches on the touch panel and recalibrating reference values. The device includes a plate having a lower face for placing the device on the touch panel; and an upper face with a matrix of entry zones having a thickness enabling a detection of a finger by the touch panel; a flat contact pad electrically conductive and fixedly attached to the lower face; and a network of conductive tracks stretching over at least a part of the upper face and being electrically connected to the contact pad.