SECTION 12 FULLSTEP OUTPUT SIGNAL The FULLSTEP output signal from the IM481H is an active high output at pin 18. This
output is TRUE for the duration of the full step. A full step occurs when either Phase A or
Phase B cross through zero (i.e. full current in one winding and zero current in the other
winding). This fullstep position is a common position no matter what resolution is
selected.
The fullstep output can be used to count the number of mechanical full steps the motor
has traveled without having to count the number of microsteps in between. A controller
that utilizes this output can greatly reduce its position tracking overhead and thus
substantially increasing its throughput.
The Direction and Microstep Resolution Select inputs are syncronized with the positive
going edge of the Step Clock input. When the Step Clock input goes high, the Direction
and Microstep Select inputs are latched and further changes to these inputs are ignored
until the next rising edge of the Step Clock input.
After these signals are latched, the IM481H looks to see if any changes have occured to
the Direction and the Microstep Select inputs. If a change has occurred, the IM481H will
execute the change before taking the next step. Only AFTER the change has been
executed will the step be taken. If no change has occured the IM481H will simply take
the next step. (This feature works as an automatic debounce for the Direction and
Microstep Select inputs.)
The minimum pulse width for the Step Clock input is 75nS. The typical execution time for
a Direction or Microstep Select change is 100nS. The typical execution time for a Step
input is 100nS.
The Reset and Enable inputs are asynchronous to any input and can be changed at any
time.
The Reset requires a minimum pulse width of 10µS (See Section 14 for more
information).
The Fullstep output typically occurs 75nS after the positive edge of the Step Clock
(excluding changes to the Direction or the Microstep Select inputs).
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