GD32W51x User Manual
165
0: Disable the High speed 20 ~ 52 MHz crystal oscillator (HXTAL) clock monitor
1: Enable the High speed 20 ~ 52 MHz crystal oscillator (HXTAL) clock monitor
When the hardw are detects that the HXTAL clock is stuck at a low or high state, the
internal hardw are w ill sw itch the system clock to be the internal high speed IRC16M
RC clock. The w ay to recover the original system clock is by either an external reset,
pow er on reset or clearing CKMIF by softw are.
Note: When the HXTAL clock monitor is enabled, the hardw are w ill automatically
enable the IRC16M internal RC oscillator regardless of the control bit, IRC16ME N,
state.
18
HXTALBPS
High speed crystal oscillator (HXTAL) clock bypass mode enable
The HXTALBPS bit can be w ritten only if the HXTALEN and HXTALPU both are 0.
0: Enable the HXTAL Bypass mode in w hich the HXTAL output clock is equal to the
input
clock.
1: Disable the HXTAL Bypass mode.
17
HXTALSTB
High speed crystal oscillator (HXTAL) clock stabilization flag
Set by hardw are to indicate if the HXTAL oscillator is stable and ready for use.
0: HXTAL oscillator is not stable
1: HXTAL oscillator is stable
16
HXTALEN
High Speed crystal oscillator (HXTAL) enable
Set and reset by softw are. This bit cannot be reset if the HXTAL clock is used as
the system clock or the PLL input clock w hen PLL clock is selected to the system
clock. Reset by hardw are w hen entering Standby mode.
If enable PLLDIG or
RFPLL, this bit need be set to 1.
0: High speed crystal oscillator disabled
1: High speed crystal oscillator enabled
15:8
IRC16MCALIB[7:0]
Internal 16MHz RC Oscillator calibration value register
These bits are load automatically at pow er on.
7:3
IRC16MA DJ[4:0]
Internal 16MHz RC Oscillator clock trim adjust value
These bits are set by softw are. The trimming value is these bits (IRC16MA DJ)
added to the IRC16MCALIB[7:0] bits. The trimming value should trim the IRC16M
to 16 MHz ± 1%.
2
RCUPRIP
RCU privilege protection
Set and reset by softw are. This bit can be read by both privileged or unprivileged
access. w hen set, it can only be cleared by a privileged access.
0: RCU registers can be accessed by a privileged or non-privileged access.
1: RCU registers can be accessed only by a privileged access except
RCU_AHBxSECSTAT, RCU_APBxSECSTAT and RCU_SECSTA T.
An unprivileged access to RCU registers is RAZ/WI.
If TrustZone security is enabled (TZEN = 1), w hen the RCU is not secure, the
RCUPRIV bit can be w ritten by a secure or non-secure privileged access. if the RCU
is secure, the RCUPRIV bit can be w ritten only by a secure privileged access. A