m30833fjgp Renesas Electronics Corporation., m30833fjgp Datasheet - Page 78

• Manufacturer Part Number: m30833fjgp
• Description: Renesas 16/32-bit Single-chip Microcomputer M16c Family / M32c/80 Series
• Manufacturer: Renesas Electronics Corporation.

R
R
M
e
E
7.2 Bus Control
. v
J
3
0
2
1
Signals required to access external devices are provided and software wait states are inserted as follows.
The signals are available in memory expansion mode and microprocessor mode only.
7.2.1 Address Bus and Data Bus
7.2.2 Chip-Select Signal
9
C
3 .
B
The address bus is a signal accessing 16M-byte space and uses 24 control pins; A
is the inversed output signal of the highest-order address bit.
The data bus is a signal which inputs and outputs data. The DS register selects the 8-bit data bus from D
to D
BYTE pin, the data bus accessing the external memory space 3 becomes the 8-bit data bus after reset.
When applying an "L" signal to the BYTE pin, the data bus accessing the external memory space 3
becomes the 16-bit data bus.
When changing single-chip mode to memory expansion mode, the address bus is in an indeterminate
state until the microcomputer accesses an external memory space.
When using the DRAMC to access DRAM area, row addresses and column addresses are multiplexed
and output via A
The chip-select signal shares ports with A
determine which CS area is accessed and how many chip-select signals are output. A maximum of four
chip-select signals can be output.
In microprocessor mode, the chip-select signal is not output after reset. A
chip-signal signal.
The chip-select signal becomes "L" while the microcomputer accesses the external CSi area (i=0 to 3). It
becomes high ("H") when the microcomputer accesses another external memory space or an internal
memory space. Figure 7.2 shows an example of the address bus and chip-select signal output.
8 /
0
1
0
3
3
J
G
4
7
a
0 -
n
o r
or the 16-bit data bus from D
3 .
1
u
, 1
3
p
1
2
(
0
M
0
3
6
2
C
8
_____
8 /
to A
Page 55
, 3
20.
M
3
2
C
f o
8 /
4
8
3
8
) T
0
to D
15
0
for each external space. When applying an "H" signal to the
to A
22
and A
_____
23
. The PM11 to PM10 bits in the PM1 register
_____
23
, however, can perform as the
0
______
to A
22
and A
______
23
. A
______
7. Bus
23
0