STEP and DIRECTION Control Circuit for Disc Drive
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
A logic circuit for the step/direction drive control of a stepping motor comprises a pair of flip-flops. cross-coupled to form a four-step ring counter. Referring to the figure, the direction of the stepper drive is determined by the phase of ACCESS 0 and ACCESS 1 drive lines. The flip-flops FF1 and FF2 are initialized through the POWER ON RESET, and then each pulse on the STEP line will switch one of the flip-flops. With a "high" signal on the DIRECTION line, flip-flop FF2 data input is gated from FF1-Q and FF1 data from FF2-Q. In this mode, ACCESS 0 will lag ACCESS 1 by 90Œ and cause the access head of the disc drive to step in the "out" direction with each pulse applied to the STEP line. With a "low" signal on the DIRECTION line, FF1 data input is gated from FF2-Q while FF2 data input is gated from FF1-Q.