GD32W51x User Manual
166
nonsecure w rite is ignored.
A secure unprivileged w rite access on RCUPRIV bit is ignored.
1
IRC16MSTB
IRC16M Internal 16MHz RC Oscillator stabilization flag
Set by hardw are to indicate if the IRC16M oscillator is stable and ready for use.
0: IRC16M oscillator is not stable
1: IRC16M oscillator is stable
0
IRC16MEN
Internal 16MHz RC oscillator enable
Set and reset by softw are. This bit cannot be reset if the IRC16M clock is used as
the system clock. Set by hardw are w hen leaving Deep-sleep or Standby mode or
the HXTAL clock is stuck at a low or high state w hen CKMEN is set.
0: Internal 16 MHz RC oscillator disabled
1: Internal 16 MHz RC oscillator enabled
6.5.2.
PLL register (RCU_PLL)
Address offset: 0x04
Reset value: 0x0000 3010
To configure the PLL clock, refer to the following formula:
CK_PLLVCOSRC = CK_PLLSRC / PLLPSC
CK_PLLVCO = CK_PLLVCOSRC × PLLN
CK_PLLP = CK_PLLVCO / PLLP
This register can be accessed by byte(8-bit), half-word(16-bit) and word(32-bit)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
PLLP[1:0]
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
PLLSEL
PLLN[8:0]
PLLPSC[5:0]
rw
rw
rw
Bits
Fields
Descriptions
31:18
Reserved
Must be kept at reset value.
17:16
PLLP[1:0]
The PLLP output frequency division factor from PLL VCO clock
Set and reset by softw are w hen the PLL is disable. These bits used to generator
PLLP output clock (CK_PLLP) from PLL VCO clock (CK_PLLVCO). The CK_PLLP
is used to system clock (no more than 180MHz). The CK_PLLVCO is described in
PLLN bits in RCU_PLL register.
00 : CK_PLLP = CK_PLLVCO / 2
01 : CK_PLLP = CK_PLLVCO / 4
10 : CK_PLLP = CK_PLLVCO / 6
11 : CK_PLLP = CK_PLLVCO / 8