Panasonic MN101L Series

Chapter 4
Clock/ Mode/ Voltage Control
IV - 16 Mode Control Function
 Clock Change from HRCCLK to HOSCCLK
Figure:4.2.4 shows the clock change procedure from HRCCLK to HOSCCLK.
Figure:4.2.4 Clock Change Flow from HRCCLK to HOSCCLK
..
Before changing the operating clock from HRCCLK to HOSCCLK, set the HCLKCNT.HOSC-
CNT to "1" and the wait time to stabilize the frequency of HOSCLK must be ensured.
After HOSCCNT is stable, set the HCLKCNT.HCLKSEL to "1".
The oscillation stabilization wait time should be determined in consultation with the manufac-
turer of oscillator.
..
 Clock Change from HOSCCLK to HRCCLK
Figure:4.2.5 shows the clock change procedure from HOSCCLK to HRCCLK.
Figure:4.2.5 Clock Change Flow from HOSCCLK to HRCCLK
External high-speed oscillation
stabilization wait time
Start the external high-speed oscillation
HCLKCNT.HOSCCNT = 1
Switching the source oscillation of fosc
HCLKCNT.HCLKSEL=1
HCLKCNT.HOSCCNT == 1
NO
YES
NORMAL mode
(SYSCLK = HRCCLK)
NORMAL mode
(SYSCLK = HOSCCLK)
Internal high-speed oscillation
stabilization wait time (15 µs)
Start the internal high-speed oscillation
HCLKCNT.HRCCNT = 1
Switching the source oscillation of HCLK
HCLKCNT.HCLKSEL = 0
HCLKCNT.HRCCNT == 1
NO
YES
NORMAL mode
(SYSCLK = HOSCCLK)
NORMAL mode
(SYSCLK = HRCCLK)