Chapter 4
Clock/ Mode/ Voltage Control
IV - 18 Mode Control Function
Clock Change from SRCCLK to SOSCCLK
Figure:4.2.7 shows the clock change procedure from SRCCLK to SOSCCLK.
Figure:4.2.7 Clock Change Flow from SRCCLK to SOSCCLK
..
To change the operating clock from the internal low-speed oscillation to the external low-
speed oscillation, set the SCLKSEL bit of SCLKCNT register to "1" after setting the SOSC-
CNT bit of SCLKCNT register to "1" and the enough oscillation stabilization wait time has
elapsed.
The oscillation stabilization wait time should be determined in consultation with the manufac-
turer of oscillator.
..
Clock Change from SOSCCLK to SRCCLK
Figure:4.2.8 shows the clock change procedure from SOSCCLK to SRCCLK.
Figure:4.2.8 Clock Change Flow from SOSCCLK to SRCCLK
Start the external low-speed oscillation
SCLKCNT.SOSCCNT = 1
SCLKCNT.SOSCCNT == 1
NO
YES
SLOW mode
(SYSCLK = SRCCLK)
SLOW mode
(SYSCLK = SOSCCLK)
External low-speed oscillation
stabilization wait time
Switching the source oscillation of SCLK
SCLKCNT.SCLKSEL = 0
Start the internal low-speed oscillation
SCLKCNT.SRCCNT = 1
SCLKCNT.SRCCNT == 1
NO
YES
SLOW mode
(SYSCLK = SOSCCLK)
SLOW mode
(SYSCLK = SRCCLK)
Internal low-speed oscillation
stabilization wait time (100 µs)
Switching the source oscillation of SCLK
SCLKCNT.SCLKSEL = 0
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