Abstract: Integrated circuitry, comprising: a sampling terminal for connecting the integrated circuitry to an external capacitance; sampling means operatively connected to the terminal to take samples, each sample having a sample value; and control means configured, whilst said external capacitance is connected to the sampling terminal, to: internally connect the sampling terminal, or another terminal of the integrated circuitry to which the external capacitance is also connected, to a given voltage-potential source to effect a change in charge stored on the external capacitance, the given voltage-potential source being available within the integrated circuitry when it is in use; cause the sampling means to take a plurality of samples over a period whilst that external capacitance charges or discharges following and/or during said change in charge; and judge whether an event has occurred in dependence upon the plurality of samples.