513
CHAPTER 22 EXTERNAL DEVICE EXPANSION FUNCTION
ASTB
WR
Higher Address
AD0 to AD7
A8 to A15
WAIT
Hi-Z
Lower Address
Write Data
ASTB
WR
AD0 to AD7
A8 to A15
Lower Address
Write Data
Higher Address
Internal Wait Signal
(
1-clock wait
)
Hi-Z
ASTB
WR
AD0 to AD7
A8 to A15
Lower Address
Write Data
Hi-Z
Higher Address
Figure 22-6. External Memory Write Timing
(a) No wait (PW1, PW0 = 0, 0) setting
(b) Wait (PW1, PW0 = 0, 1) setting
(c) External wait (PW1, PW0 = 1, 1) setting