518
CHAPTER 22 EXTERNAL DEVICE EXPANSION FUNCTION
22.3 External Device Expansion Function Timing
Timing control signal output pins in the external memory expansion mode are as follows.
(1) RD pin (Alternate function: P64)
Read strobe signal output pin. The read strobe signal is output in data accesses and instruction fetches from
external memory.
During internal memory access, the read strobe signal is not output (maintains high level).
(2) WR pin (Alternate function: P65)
Write strobe signal output pin. The write strobe signal is output in data access to external memory.
During internal memory access, the write strobe signal is not output (maintains high level).
(3) WAIT pin (Alternate function: P66)
External wait signal input pin. When the external wait is not used, the WAIT pin can be used as an input/output
port.
During internal memory access, the external wait signal is ignored.
(4) ASTB pin (Alternate function: P67)
Address strobe signal output pin. Timing signal is output without regard to the data accesses and instruction
fetches from external memory. The ASTB signal is also output when the internal memory is accessed.
(5) AD0 to AD7, A8 to A15 pins (Alternate function: P40 to P47, P50 to P57)
Address/data signal output pin. Valid signal is output or input during data accesses and instruction fetches
from external memory.
These signals change when the internal memory is accessed (output values are undefined).
Timing charts are shown in Figure 22-4 to 22-7.
Summary of Contents for PD78052
Page 2: ...2 MEMO ...
Page 8: ...8 MEMO ...
Page 16: ...16 MEMO ...
Page 36: ...36 MEMO ...
Page 158: ...158 MEMO ...
Page 174: ...174 MEMO ...
Page 240: ...240 MEMO ...
Page 260: ...260 MEMO ...
Page 340: ...340 MEMO ...
Page 392: ...392 MEMO ...
Page 438: ...438 MEMO ...
Page 482: ...482 CHAPTER 20 REAL TIME OUTPUT PORT MEMO ...
Page 510: ...510 MEMO ...
Page 524: ...524 MEMO ...
Page 560: ...560 MEMO ...
Page 576: ...576 MEMO ...
Page 598: ...598 MEMO ...
Page 602: ...602 MEMO ...