W77E532 Datasheet, PDF (40/86 Pages) Winbond – 8 BIT MICROCONTROLLER

W77E532/W77E532A
Wait State Control Signal
Either with the software using stretch value to change the required machine cycle of MOVX instruction,
the W77E532A provides another hardware signal WAIT to implement the wider duration of external
data access timing. This wait state control signal is the alternate function of P4.0 such that it can only
be invoked to 44-pin PLCC/QFP package type. The wait state control signal can be enabled by setting
WS (WSCON.7) bit. When enabled, the setting of stretch value decides the minimum length of MOVX
instruction cycle and the device will sample the WAIT pin at each C3 state before the rising edge of
read/write strobe signal during MOVX instruction. Once this signal being recognized, one more
machine cycle (wait state cycle) will be inserted into next cycle. The inserted wait state cycles are
unlimited, so the MOVX instruction cycle will end in which the wait state control signal is deactivated.
Using wait state control signal allows a dynamically access timing to a selected external peripheral. The
WS bit is accessed by the Timed Access Protection procedure.
Set WS bit and stretch value = 0 to enable wait signal.
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Publication Release Date: June 30, 2009
Revision A10