CHAPTER 2-1: Clock
FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E 53
Figure 4-2 Example of Sub Oscillation Setup Procedure (Except TYPE5-M4 products)
Notes:
− Set the sub clock stabilization wait time (SCM_TMR.SOWT) longer than the VBAT RTC 32 k
oscillation boost setting time [BOOST:BOOST[1:0]].
− The following combination of settings is prohibited:
Start the sub oscillation enabling
Turn off VCC
power supply?
Enable the sub clock oscillation of the system clock mode
control register. (SCM_CTL.SOSCE=1)
Set VBAT register (VBPFR.SPSR[1:0]=0b01)
Set 32k oscillation
Access the clock stabilization wait time register (CSW_TMR). Set the sub clock
oscillation stabilization wait time. Access the interrupt enable register(INT_ENR).
Set the oscillation stabilization wait interrupt.
Start the oscillation stabilization wait.
Confirm the sub clock oscillation stabilization bit of the system clock mode
status register.(SCM_STR.SORDY=1)
Complete the oscillation stabilization wait.
Complete the sub oscillation enable.
VBAT register (WTOSCCNT[1:0]=0b00 Set 32k
oscillation clock control connection disabled
VBAT register (WTOSCCNT[1:0]=0b10)
Set 32k oscillation clock control connection enabled. Set
32k oscillation enabled.
Access VBAT RTC LVD detection register (VDET).
Release PONR of VBAT domain
Set 32k oscillation boost time and transfer clock division to
VBAT register (BOOST.BOOST[1:0]) and VBAT register
(VB_CLKDIV).
Access VBAT register (CCB, CCS).
Set 32k oscillation circuit and oscillation current value.
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