System for digitally emulating the analog position of a PC game port joystick

摘要

A joystick system provides a digital representation of the setting of a joystick potentiometer. The voltage of the joystick is supplied to an analog-to-digital converter, the output of which then is used to load a counter. In one mode of operation, the counter counts down to zero at some multiple of the sample rate. When the counter reaches zero, the time interval representative of the joystick position is indicated; and this output is indicative of the joystick position. In an alternative mode of operation, the counter is used as a data latch and the joystick position is digitally read from the counter, which keeps the data latched until the next sample cycle from the joystick position.