M16C Datasheet, PDF (27/262 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Preliminary Specifications REV.B
Mitsubishi microcomputers
Specifications in this manual are tentative and subject to change.
M16C / 6N Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Bus Control
Chip select control register
b7 b6 b5 b4 b3 b2 b1 b0
Symbol
CSR
Address
000816
When reset
0116
Bit symbol
CS0
CS1
CS2
CS3
CS0W
CS1W
CS2W
CS3W
Bit name
CS0 output enable bit
CS1 output enable bit
CS2 output enable bit
CS3 output enable bit
CS0 wait bit
CS1 wait bit
CS2 wait bit
CS3 wait bit
Figure 3-5. Chip select control register
Function
0 : Chip select output disabled
(Normal port pin)
1 : Chip select output enabled
RW
0 : Wait state inserted
1 : No wait state
(3) Read/write signals
With a 16-bit data bus (BYTE pin =“L”), bit 2 of the processor mode register 0 (address 000416) select the
combinations of RD, BHE, and WR signals or RD, WRL, and WRH signals. With an 8-bit data bus (BYTE pin
= “H”), use the combination of RD, WR, and BHE signals. (Set bit 2 of the processor mode register 0
(address 000416) to “0”.) Tables 3-4 and 3-5 show the operation of these signals.
After a reset has been cancelled, the combination of RD, WR, and BHE signals is automatically selected.
When switching to the RD, WRL, and WRH combination, do not write to external memory until bit 2 of the
processor mode register 0 (address 000416) has been set (Note).
Note: Before attempting to change the contents of the processor mode register 0, set bit 1 of the protect
register (address 000A16) to “1”.
Table 3-4. Operation of RD, WRL, and WRH signals
Data bus width
RD
L
16-bit
H
(BYTE = L )
H
H
WRL
H
L
H
L
WRH
H
H
L
L
Status of external data bus
Read data
Write 1 byte of data to even address
Write 1 byte of data to odd address
Write data to both even and odd addresses
Table 3-5. Operation of RD, WR, and BHE signals
Data bus width RD
H
L
16-bit
H
(BYTE = L )
L
H
L
8-bit
H
(BYTE = H )
L
WR
BHE
A0
L
L
H
H
L
H
L
H
L
H
H
L
L
L
L
H
L
L
L
Not used H / L
H
Not used H / L
Status of external data bus
Write 1 byte of data to odd address
Read 1 byte of data from odd address
Write 1 byte of data to even address
Read 1 byte of data from even address
Write data to both even and odd addresses
Read data from both even and odd addresses
Write 1 byte of data
Read 1 byte of data
27