Renesas 7700 FAMILY User Manual page 46

Table 2.5.2 Methods for setting processor modes
Processor mode
Single-chip mode
Memory expansion mode
Microprocessor mode
Notes 1: The microcomputer starts operating in the single-chip mode after a reset. The microcomputer can
be switched to the other processor modes by setting the processor mode bits.
2: The microcomputer starts operating in the microprocessor mode after a reset. The microcomputer
cannot operate in the other modes, so that fix the processor mode bits as follows:
•b1 = "1" and b0 = "0."
b7 b6 b5 b4 b3 b2
0 0
Fig. 2.5.4 Structure of processor mode register 0
CENTRAL PROCESSING UNIT (CPU)
Vss (0 V) (Note 1)
Vss (0 V) (Note 1)
Vss (0 V) (Note 1)
Vcc (5 V) (Note 2)
b1 b0
Processor mode register 0 (Address 5E
Bit
Processor mode bits
0
1
Fix this bit to "0."
2
Software reset bit
3
Interrupt priority detection time
4
select bits
5
Fix this bit to "0."
6
Clock φ
output select bit
1
7
Notes 1: While supplying the Vcc level to the CNVss pin, this bit becomes "1"
after a reset. (Fixed to "1.")
2: This bit is ignored in the microprocessor mode. (It may be either "0" or "1.")
: Bits 7 to 2 are not used for setting of the processor mode.
7751 Group User's Manual
CNVss pin level
)
16
Bit name
b1 b0
0 0 : Single-chip mode
0 1 : Memory expansion mode
1 0 : Microprocessor mode
1 1 : Not selected
The microcomputer is reset by
writing "1" to this bit. The value is
"0" at reading.
b5 b4
0 0 : 7 cycles of φ
0 1 : 4 cycles of φ
1 0 : 2 cycles of φ
1 1 : Not selected
0 : Clock φ
(P4
(Note 2)
2
I/O port.)
1 : Clock φ
(P4
2
put pin.)
2.5 Processor modes
Processor mode bits
b1
0
0
1
Functions
output disabled
1
functions as a programmable
output enabled
1
functions as a clock φ
out-
1
b0
0
1
0
RW
At reset
0 RW
0
RW
(Note 1)
RW
0
0 WO
RW
0
RW
0
RW
0
0 RW
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