Renesas Single-Chip Microcomputer M37531T-ADS Información técnica Pagina 50

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Mitsubishi microcomputer
s
M16C / 62A Grou
p
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTE
R
Clock Generating Circuit
37
Figure 1.10.4 shows the system clock control registers 0 and 1.
Figure 1.10.4. Clock control registers 0 and 1
System clock control register 0 (Note 1)
Symbol Address When reset
CM0 0006
16
48
16
Bit name FunctionBit symbol
b7 b6 b5 b4 b3 b2 b1 b0
0 0 : I/O port P5
7
0 1 : f
C
output
1 0 : f
8
output
1 1 : f
32
output
b1 b0
CM07
CM05
CM04
CM03
CM01
CM02
CM00
CM06
Clock output function
select bit
(Valid only in single-chip
mode)
WAIT peripheral function
clock stop bit
0 : Do not stop peripheral function clock in wait mode
1 : Stop peripheral function clock in wait mode (Note 8)
X
CIN
-X
COUT
drive capacity
select bit (Note 2)
0 : LOW
1 : HIGH
Port X
C
select bit 0 : I/O port
1 : X
CIN
-X
COUT
generation
Main clock (X
IN
-X
OUT
)
stop bit (Note 3, 4, 5)
0 : On
1 : Off
Main clock division select
bit 0 (Note 7)
0 : CM16 and CM17 valid
1 : Division by 8 mode
System clock select bit
(Note 6)
0 : X
IN
, X
OUT
1 : X
CIN
, X
COUT
Note 1: Set bit 0 of the protect register (address 000A
16
) to 1 before writing to this register.
Note 2: Changes to 1 when shiffing to stop mode and at a reset.
Note 3: When entering power saving mode, main clock stops using this bit. When returning from stop mode and
operating with X
IN
, set this bit to 0. When main clock oscillation is operating by itself, set system clock select
bit (CM07) to 1 before setting this bit to 1.
Note 4: When inputting external clock, only clock oscillation buffer is stopped and clock input is acceptable.
Note 5: If this bit is set to 1, X
OUT
turns H. The built-in feedback resistor remains being connected, so X
IN
turns
pulled up to X
OUT
(H) via the feedback resistor.
Note 6: Set port Xc select bit (CM04) to 1 and stabilize the sub-clock oscillating before setting to this bit from 0 to 1.
Do not write to both bits at the same time. And also, set the main clock stop bit (CM05) to 0 and stabilize the
main clock oscillating before setting this bit from 1 to 0.
Note 7: This bit changes to 1 when shifting from high-speed/medium-speed mode to stop mode and at a reset. When
shifting from low-speed/low power dissipation mode to stop mode, the value before stop mode is retained.
Note 8: f
C32
is not included. Do not set to 1 when using low-speed or low power dissipation mode.
System clock control register 1 (Note 1)
Symbol Address When reset
CM1 0007
16
20
16
Bit name FunctionBit symbol
b7 b6 b5 b4 b3 b2 b1 b0
CM10
All clock stop control bit
(Note4)
0 : Clock on
1 : All clocks off (stop mode)
Note 1: Set bit 0 of the protect register (address 000A
16
) to
1 before writing to this register.
Note 2: This bit changes to 1 when shifting from high-speed/medium-speed mode to stop mode and at a reset. When
shifting from low-speed/low power dissipation mode to stop mode, the value before stop mode is retained.
Note 3: Can be selected when bit 6 of the system clock control register 0 (address 0006
16
) is
0. If
1, division mode is
fixed at 8.
Note 4: If this bit is set to 1, X
OUT
turns H, and the built-in feedback resistor is cut off. X
CIN
and X
COUT
turn high-
impedance state.
CM15
X
IN
-X
OUT
drive capacity
select bit (Note 2)
0 : LOW
1 : HIGH
WR
WR
CM16
CM17
Reserved bit
Always set to
0
Reserved bit
Always set to
0
Main clock division
select bit 1 (Note 3)
0 0 : No division mode
0 1 : Division by 2 mode
1 0 : Division by 4 mode
1 1 : Division by 16 mode
b7 b6
00
Reserved bit
Always set to
0
Reserved bit
Always set to
0
00
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