Renesas R8C series User Manual

R8C/1A Group, R8C/1B Group 10. Clock Generation Circuit
Rev.1.30 Dec 08, 2006 Page 76 of 315
REJ09B0252-0130
10.6 Notes on Clock Generation Circuit
10.6.1 Stop Mode
When entering stop mode, set the FMR01 bit in the FMR0 register to 0 (CPU rewrite mode disabled) and the
CM10 bit in the CM1 register to 1 (stop mode). An instruction queue pre-reads 4 bytes from the instruction
which sets the CM10 bit to 1 (stop mode) and the program stops.
Insert at least 4 NOP instructions following the JMP.B instruction after the instruction which sets the CM10 bit
to 1.
• Program example to enter stop mode
BCLR 1,FMR0 ; CPU rewrite mode disabled
BSET 0,PRCR ; Protect disabled
FSET I ; Enable interrupt
BSET 0,CM1 ; Stop mode
JMP.B LABEL_001
LABEL_001 :
NOP
NOP
NOP
NOP
10.6.2 Wait Mode
When entering wait mode, set the FMR01 bit in the FMR0 register to 0 (CPU rewrite mode disabled) and
execute the WAIT instruction. An instruction queue pre-reads 4 bytes from the WAIT instruction and the
program stops. Insert at least 4 NOP instructions after the WAIT instruction.
• Program example to execute the WAIT instruction
BCLR 1,FMR0 ; CPU rewrite mode disabled
FSET I ; Enable interrupt
WAIT ; Wait mode
NOP
NOP
NOP
NOP
10.6.3 Oscillation Stop Detection Function
Since the oscillation stop detection function cannot be used if the main clock frequency is below 2 MHz, set bits
OCD1 to OCD0 to 00b (oscillation stop detection function disabled) in this case.
10.6.4 Oscillation Circuit Constants
Ask the manufacturer of the oscillator to specify the best oscillation circuit constants for your system.
10.6.5 High-Speed On-Chip Oscillator Clock
The high-speed on-chip oscillator frequency may be changed up to 10%
(1)
in flash memory CPU rewrite mode
during auto-program operation or auto-erase operation.
The high-speed on-chip oscillator frequency after auto-program operation ends or auto-erase operation ends is
held the state before the program command or block erase command is generated. Also, this note is not
applicable when the read array command, read status register command, or clear status register command is
generated. The application products must be designed with careful considerations for the frequency change.
NOTE:
1. Change ratio to 8 MHz frequency adjusted in shipping.

Renesas R8C series Specifications

General

Brand	Renesas
Model	R8C series
Category	Computer Hardware
Language	English