M30622M4 MITSUBISHI [Mitsubishi Electric Semiconductor], M30622M4 Datasheet - Page 25

• Manufacturer Part Number: M30622M4
• Description: SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

Memory Space Expansion Functions
The data bank register is made up of the bank selection bits (bits 5 through 3) and the offset bit (bit 2). The
bank selection bits are used to set a bank number for accessing data lying between 40000
BFFFF
Figure 1.8.5 shows the memory location and chip select areas in expansion mode 2.
The area relevant to CS0 ranges from 40000
BFFFF
- CS1 only in accessing data. In fetching a program, bank 7 (111
area from C0000
data or to fetching a program.
In accessing an area irrelevant to CS0, a chip select signal CS3 (4000
27FFF
Figure 1.8.6 shows an example of connecting the MCU with a 4-M byte ROM and to a 128-K byte SRAM.
Connect the chip select of 4-M byte ROM with CS0. Connect M16C’s CS3, CS2, and CS1 with address
inputs AD21, AD20, and AD19 respectively. Connect M16C’s output A19 with address input AD18. Fig-
ure 1.8.7 shows the relationship between addresses of the 4-M byte ROM and those of M16C.
In this mode, memory is
banked every 512 K bytes,
so that data access in differ-
ent banks requires switching
over banks. However, data
on bank boundaries when
offset bit = 0 can be ac-
cessed successively by set-
ting the offset bit to 1, be-
cause in which case the
memory address is offset by
40000
bytes of data located at ad-
d r e s s e s 0 F F F F F
100000
can be accessed succes-
sively without having to
change the bank bit by set-
ting the offset bit to 1 and
then accessing addresses
07FFFF
On the other hand, the
SRAM’s chip select assumes
that CS0=1 (not selected)
and CS2=0 (selected), so
connect CS0 with S2 and
CS2 with S1. If the SRAM
doesn’t have a bipolar chip
select input terminal, decode
_______
CS0 and CS2 externally.
_______
_______
_______
_______
16
16
16
16
16
16
), and CS1 (28000
. For example, two
, the bank number set by use of the bank selection bits are output from the output terminals CS3
. Assigning 1 to the offset bit provides the means to set offsets covering 40000
_______
_______
and 800000
of 4-Mbyte ROM
____
_______
16
through FFFFF
_______
1 6
16
a n d
.
16
- 3FFFF
Figure 1.8.6. An example of connecting the MCU with external
16
_______
, bank 7 (111
16
) is output depending on the address as in the past.
Note: If only one chip select terminal (S1 or S2) is present,
16
A n e x a m p l e o f c o n n e c t i n g t h e M C U w i t h
e x t e r n a l m e m o r i e s i n e x p a n s i o n m o d e 2
( M 3 0 6 2 2 M C , M i c r o p r o c e s s o r m o d e )
_______
through FFFFF
A 0 t o A 1 6
memories in expansion mode 2
2
D0 to D7
decoding by use of an external circuit is required.
) is output from CS3 - CS1 without regard to accessing
CS1
CS2
CS3
CS0
A17
A19
W R
RD
16
_______
. As for the area from 40000
2
_______
17
) is output from CS3 - CS1. As for the
8
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
_______
_______
16
_______
W
D Q 0 t o D Q 7
AD0 to AD16
A D 1 7
AD18
A D 1 9
A D 2 0
A D 2 1
O E
C S
D Q 0 t o D Q 7
A D 0 t o A D 1 6
O E
S 2
S 1
- 7FFF
_______
16
Mitsubishi microcomputers
M16C / 62 Group
_______
), CS2 (8000
16
_______
_______
.
16
through
16
_______
and
16
-
25