W77E532_07 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: November 19, 2007
Revision A9