POT_INTERFACE

Published:2009/7/6 20:18:00 Author:May | From:SeekIC

Circuit converts resistance of pot setting to frequency with NE555 timer IC1.Frequency is measured under direct control of microprocessor program, using 8-bit counter with CPU clock as time base. Processor is programmed to clear counter, turn on counter, wait 2 ms, turn off counter, and read count. Result is number of cycles in 2-ms period, ranging from 1 to about 240. Relationship of frequency to control position is accurate enough for game control. R1, R2, R3, and 01 are chosen so frequency varies from about 0.75 to 122 kHz as Ra is varied from 100K to 0. Use audio-taper pot to improve conversion linearity. Article gives subroutines for Motorola 6800 and Intel 8080 microprocessors.-C. Helmers, Getting Inputs from Joy-sticks and Slide Pots, BYTE, Feb. 1976, p 86-88.



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