M16C1N Datasheet, PDF (37/238 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/10 SERIES

M16C/1N Group
6. Clock Generation Circuit
System clock control register 0 (Note 1)
b7 b6 b5 b4 b3 b2 b1 b0
00
Symbol
CM0
Address
000616
When reset
010010002
Bit symbol
Bit name
Function
RW
Reserved bit
Set to "0"
RW
CM02
CM03
CM04
CM05
CM06
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 2) ^RW
XCIN-XCOUT drive capacity 0 : LOW
select bit (Note 3)
1 : HIGH
RW
Port XC select bit
0 : I/O port
1 : XCIN-XCOUT generation
RW
Main clock (XIN-XOUT)
stop bit (Note 4,5,6)
0 : On
1 : Off
RW
Main clock division select 0 : CM16 and CM17 valid
bit 0 (Note 7)
1 : Division by 8 mode
RW
CM07 System clock select bit
(Note 8)
0 : XIN, XOUT
1 : XCIN, XCOUT
RW
Note 1: Set bit 0 of the protect register (address 000A16) to "1" before writing to this register.
Note 2: fc32 is not included. Do not set to "1" when using low-speed, low power dissipation or on-chip oscillator mode.
Note 3: Changes to "1" when shifting to stop mode.
Note 4: This bit is used to stop the main clock when placing the device in a low-power mode. If you want to operate with XIN after
exiting from the stop mode, set this bit to "0". When operating with a self-excited oscillator, set the system clock select bit
(CM07) to "1" before setting this bit to "1".
Note 5: When inputting external clock, only clock oscillation buffer is stopped and clock input is acceptable.
Note 6: If this bit is set to "1", XOUT turns "H". The built-in feedback resistor remains being ON, so XIN turns pulled up to XOUT ("H")
via the feedback resistor.
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: Set port Xc select bit (CM04) to "1" before setting this bit to "1". Can not write to both bits at the same time.
System clock control register 1 (Note 1)
b7 b6 b5 b4 b3 b2 b1 b0
000
Symbol
CM1
Address
000716
When reset
001000002
Bit symbol
Bit name
Function
RW
CM10 All clock stop control bit
(Note 2)
0 : Clock on
1 : All clocks off (stop mode)
RW
Reserved bit
Set to "0"
RW
CM14 On-chip oscillation stop bit 0 : Oscillation enabled
1 : Oscillation stopped (Note 3)
RW
CM15 XIN-XOUT drive capacity
select bit (Note 4)
0 : LOW
1 : HIGH
RW
CM16 Main clock division
b7 b6
0 0 : No division mode
select bit 1 (Note 5)
0 1 : Division by 2 mode
RW
CM17
1 0 : Division by 4 mode
1 1 : Division by 16 mode
Note 1: Set bit 0 of the protect register (address 000A16) to "1" before writing to this register.
Note 2: The mode of power control cannot be shifted on the stop mode directly from the on-chip oscillator.
If this bit is set to "1", XOUT turns "H", and the built-in feedback resistor is ineffective.
Note 3: This bit can be set to "1" only when both the main clock switch bit (CM22) and clock monitor bit (CM23) are set to "0".
Moreover, this bit is automatically set to "0" if the main clock switch bit (CM22) is set to "1".
Note 4: This bit changes to "1" when shifting from high-speed/middle-speed mode to stop mode or at reset. When shifting from low-
speed/low power dissipation mode to stop mode, the value before stop mode is retained.
Note 5: Can be selected when bit 6 of the system clock control register 0 (address 000616) is "0". If "1", division mode is fixed at 8.
Figure 6.2 System clock control registers 0 and 1
Rev.1.00 Oct 20, 2004 page 25 of 222
REJ09B0007-0100Z