TOUCH SENSOR SYSTEM AND MICROCOMPUTER

Detecting a touch on a touch sensor is performed using a microcomputer without requiring a large-resistance resistor. A capacitive electrode of the touch sensor is coupled to an external terminal of the microcomputer. The microcomputer comprises a current source circuit (e.g., constant current circuit) and an interface section which are coupled to the external terminal, a counter circuit coupled to the interface section, and a central processing unit (CPU). The CPU, after initializing accumulated charge on the touch sensor by an output circuit of the interface section, integrates charge onto the touch sensor with an output current of the current source circuit, acquires a time interval counted by the counter circuit until a signal obtained from an input circuit of the interface section inverts, and discerns whether or not the touch sensor has been touched, depending on the time count value.