GD32W51x User Manual
197
1: Option byte loader reset generated
24
RSTFC
Reset flag clear
This bit is set by softw are to clear all reset flags.
0: Not clear reset flags
1: Clear reset flags
23:2
Reserved
Must be kept at reset value.
1
IRC32KSTB
IRC32K stabilization flag
Set by hardw are to indicate if the IRC32K output clock is stable and ready for use.
0: IRC32K is not stable
1: IRC32K is stable
0
IRC32KEN
IRC32K enable
Set and reset by softw are.
0: Disable IRC32K
1: Enable IRC32K
6.5.22.
PLL clock spread spectrum control register (RCU_PLLSSCTL)
Address offset: 0x80
Reset value: 0x0000 0000
This register can be accessed by byte(8-bit), half-word(16-bit) and word(32-bit)
The spread spectrum modulation is available only for the main PLL clock
The RCU_PLLSSCTL register must be written when the main PLL is disabled
This register is used to configure the PLL spread spectrum clock generation according to
the following formulas:
MODCNT = round(f
PLLIN
/4/f
mod
)
MODSTEP = round(mdamp*PLLN*2
14
/(MODCNT*100))
Where f
PLLIN
represents the PLL input clock frequency, f
mod
represents the spread spectrum
modulation frequency, mdamp represents the spread spectrum modulation amplitude
expressed as a percentage, PLLN represents the PLL clock frequency multiplication factor.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
SSCGON SS_TYPE
Reserved
MODSTEP[14:3]
rw
rw
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
MODSTEP[2:0]
MODCNT[12:0]
rw
rw
Bits
Fields
Descriptions
31
SSCGON
PLL spread spectrum modulation enable
0: Spread spectrum modulation disable
1: Spread spectrum modulation enable