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M16C/5L Group, M16C/56 Group
8.2.7
40 MHz On-Chip Oscillator Control Register 0 (FRA0)
40 MHz On-Chip Oscillator Control Register 0
b7 b6 b5 b4
b3
b2
b1
Rewrite the FRA0 register after setting the PRC0 bit in the PRCR register to 1 (write enabled).
See Table 9.3 "Clock-Related Bit Setting and Modes"to select a clock and a mode.
FRA00 (40 MHz on-chip oscillator start bit) (b0)
When using an oscillator stop/restart detect interrupt, do not set the FRA00 bit to 0 (40 MHz on-chip
oscillator off) while the FRA01 bit to 1 (40 MHz on-chip oscillator), and vice versa.
FRA01 (On-chip oscillator select bit) (b1)
Change the FRA01 bit if the both of the following conditions are met:
•
When the FRA00 bit is 1 (40 MHz on-chip oscillator on) and oscillation is stable
•
When the CM14 bit in the CM1 register is 0 (125 kHz on-chip oscillator on) and oscillation is stable
When setting the FRA01 bit to 0 (125 kHz on-chip oscillator), do not set the FRA00 bit to 0 (40 MHz on-
chip oscillator off) at the same time. Set the FRA00 bit to 0 after setting the FRA01 bit to 0.
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
b0
Symbol
FRA0
Bit Symbol
Bit Name
40 MHz on-chip oscillator start
FRA00
bit
FRA01
On-chip oscillator select bit
—
No register bits. If necessary, set to 0. The read value is undefined.
(b7-b2)
Address
0022h
Function
0 : 40 MHz on-chip oscillator off
1 : 40 MHz on-chip oscillator on
0 : 125 kHz on-chip oscillator
1 : 40 MHz on-chip oscillator
8. Clock Generator
Reset Value
XXXX XX00b
RW
RW
RW
—
Page 102 of 803
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