UPD78320 Datasheet, PDF (48/88 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLER

µPD78320, 78322
6. EXTERNAL DEVICE EXPANSION FUNCTION
The µPD78322 can expand external devices (data memory, program memory or peripheral device) for areas (4000H
to FFFFH) except the internal ROM and RAM areas. Tables 6-1 through 6-3 shows the pin used for external device access
and the pin function setting procedure.
Table 6-1. Pin Function Setting (µPD78322)
Memory Expansion
EA Pin Mode Register
MM0 to MM2 MM7
0
Port mode
1
1
0
Expansion
mode
1
Fetch Cycle
Control
Register
00H
00H
Except 00H
P40 to P47
AD0 to AD7
Pin Function
P50 to P57 P90 P91
General port
Setting prohibited
Set to A8 to
RD WR
A15 in steps
P92 P93
Remarks
General- External device
purpose port connection mode
µPD71P301
TAS TMD _{connection mode}
For P50 to P57 pins, the number of bits which serve as address buses can be changed according to the externally
expanded memory size. The memory can be expanded in steps from 256 bytes to about 48K bytes. The pins which are
not used as the address bus can be used as the general-purpose input/output port.
Table 6-2. Port and Address Setting for Port 5 (µPD78322)
P57 P56 P55 P54 P53 P52 P51 P50 External Address Space
Port Port Port Port Port Port Port Port 256 bytes or less
Port Port Port Port A11 A10 A9 A8 4K bytes or less
Port Port A13 A12 A11 A10 A9 A8 16K bytes or less
A15 A14 A13 A12 A11 A10 A9 A8 About 48K bytes or less
Table 6-3. Setting Pin Function (µPD78320)
EA Pin
Memory Expansion
Mode Register
MM7
Fetch Cycle
Control
Register
AD0 to AD7
ASTB
0
00H
AD to AD7
0
1
Except 00H
Pin Function
A8 to A15 RD WR P92 P93
Remarks
A8 to A15
µPD78322
TAS TMD
emulation mode
RD WR
General- External device
purpose port connection mode
µPD71P301
TAS TMD
connection mode
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