Browse Prior Art Database

Single Shot Control for Joystick

IP.com Disclosure Number: IPCOM000087795D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Bland, JC: AUTHOR [+3]

Abstract

Joysticks and similar devices used to control the movement of a cursor over a display screen frequently use two potentiometers, one for the X direction and one for the Y direction. The analog signal from each potentiometer indicates the displacement of the joystick from its home position.

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Single Shot Control for Joystick

Joysticks and similar devices used to control the movement of a cursor over a display screen frequently use two potentiometers, one for the X direction and one for the Y direction. The analog signal from each potentiometer indicates the displacement of the joystick from its home position.

Fig. 1 shows a circuit for converting the analog signal into a digital value. Fig. 2 is a timing diagram. Each joystick-mounted potentiometer is used as a variable resistive timing component of a single-shot. Variable resistors R, provided in series with the potentiometers, help in setting up the circuit. The single-shot inputs are strobed at approximately every 30 msec, and the outputs are compared with a Compare Time signal which is derived from either a nonvariable single-shot or from clock control circuits.

With the joystick in the normal "home" position, the outputs of the X and Y single shots are adjusted (using variable resistor R) to equal the compare time. As the joystick is moved, the outputs of either the X, Y or both single-shots become greater than or less than the compare time. This difference in signals is derived as shown and gated with the clock signal to derive up/down pulses for the X and Y counters. These counters are used to control movement of the displayed cursor in an up/down, left/right or diagonal direction. The further the joystick is moved from the home position the greater the difference between the single-shot times...