![](http://datasheet.mmic.net.cn/30000/M30622F8PGP_datasheet_2359050/M30622F8PGP_34.png)
Bus
34
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Under
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Function
Bit symbol
Bit name
Chip select control register
Symbol
Address
After reset
CSR
000816
000000012
RW
b7
b6
b5
b4
b3
b2
b1
b0
CS1
CS0
CS3
CS2
CS0 output enable bit
CS1 output enable bit
CS2 output enable bit
CS3 output enable bit
CS1W
CS0W
CS3W
CS2W
CS0 wait bit
CS1 wait bit
CS2 wait bit
CS3 wait bit
0 : Chip select output disabled
(functions as I/O port)
1 : Chip select output enabled
0 : With wait state
1 : Without wait state
RW
(Note 1, Note 2, Note 3)
Note 1: Where the RDY signal is used in the area indicated by CSi (i = 0 to 3) or the multiplex bus is used, set
the CSiW bit to “0” (Wait state).
Note 2: If the PM17 bit in the PM1 register is set to “1” (with wait state), the external area indicated by CS0 to
CS3 is always accessed with one wait state even when the CSiW bit is “1” (without wait state).
Note 3: When the CSiW bit = “0” (with wait state), the number of wait states (interms of clock cycles) can be
selected using the CSEi1W to CSEi0W bits in the CSE register.
Figure 1.7.1. CSR Register
Bus Control
The following describes the signals needed for accessing external devices and the functionality of software
wait.
(1) Address Bus
The address bus consists of 20 lines, A0 to A19. The address bus width can be chosen to be 12, 16 or
20 bits by using the PM06 bit in the PM0 register and the PM11 bit in the PM1 register. Table 1.7.1
shows the PM06 and PM11 bit set values and address bus widths.
When processor mode is changed from single-chip mode to memory extension mode, the address
bus is indeterminate until any external area is accessed.
(2) Data Bus
When input on the BYTE pin is high, 8 lines D0 to D7 comprise the data bus; when input on the BYTE
pin is low, 16 lines D0 to D15 comprise the data bus.
Do not change the input level on the BYTE pin while in operation.
(3) Chip Select Signal
______
The chip select (hereafter referred to as the CSi) signals are output from the CSi (i = 0 to 3) pins.
_____
These pins can be chosen to function as I/O ports or as CS by using the CSi bit in the CSR register.
Figure 1.7.1 shows the CSR register.
______
During 1 Mbyte mode, the external area can be separated into up to 4 by the CSi signal which is output
______
from the CSi pin. During 4 Mbyte mode, CSi signal or bank number is output from the CSi pin. Refer to
______
“Memory space expansion function”. Figure 1.7.2 shows the example of address bus and CSi signal
output in 1 Mbyte mode.
Set value(Note)
Pin function
PM11=1
P34 to P37
Address bus wide
12 bits
PM06=1
P40 to P43
PM11=0
A12 to A15
16 bits
PM06=1
P40 to P43
PM11=0
A12 to A15
20 bits
PM06=0
A16 to A19
Note 1: No values other than those shown above can be set.
Table 1.7.1. PM06 and PM11 Bits Set Value and Address Bus Width