Toshiba TLCS-900/H1 Series Manual page 28

(2) Clock gear controller
f is set according to the contents of the clock gear select register
FPH
SYSCR1<GEAR2:0> to either fc, fc/2, fc/4, fc/8 or fc/16. Using the clock gear to select a
lower value of f
FPH
Example 3: Changing to a high-frequency gear
SYSCR1 EQU 10E1H
LD (SYSCR1), XXXX0000B
LD (DUMMY), 00H
X: Don't care
(High-speed clock gear changing)
To change the clock gear, write the register value to the SYSCR1<GEAR2:0>
register.It is necessary for the warm-up time to elapse before the change occurs after
writing the register value.
There is the possibility that the instruction following the clock gear changing
instruction is executed by the clock gear before changing.To execute the instruction
following the clock gear switching instruction by the clock gear after changing, input
the dummy instruction as follows (instruction to execute the write cycle).
Example:
SYSCR1 EQU 10E1H
LD (SYSCR1), XXXX0001B
LD (DUMMY), 00H
Instruction to be executed after clock gear has changed
reduces power consumption.
; Changes f
; Dummy instruction
; Changes f
; Dummy instruction
92CH21-26
to fc/2.
SYS
to fc/4.
SYS
TMP92CH21
2009-06-19