GD32W51x User Manual
153
Figure 6-1. The system reset circuit
Fi lter
WWDGT_RSTn
FWDGT_RSTn
SW_RSTn
NRSTDPSTDBY
NRSTSTDBY
POWER_RSTn
NRST
Sys tem Res et
min 20 us
pulse generator
Backup domain reset
A backup domain reset is generated by setting the BKPRST bit in the Backup domain control
register or Backup domain power on reset (V
DD
or V
BAT
power on, if both supplies have
previously been powered off).
6.2.
Clock control unit (CCTL)
6.2.1.
Overview
The Clock Control unit provides a range of frequencies and clock functions. These include a
Internal 16M RC oscillator (IRC16M), a High Speed crystal oscillator (HXTAL), a Low Speed
Internal 32K RC oscillator (IRC32K), a Low Speed crystal oscillator (LXTAL), three Phase
Lock Loop (PLL
、
PLLDIG
、
PLLI2S),
two HXTAL clock monitor, clock prescalers, clock
multiplexers and clock gating circuitry.
The clocks of the AHB, APB and Cortex™-M33 are derived from the system clock (CK_SYS)
which can source from the IRC16M, HXTAL or PLL (PLL or PLLDIG). The maximum operating
frequency of the system clock (CK_SYS) can be up to 180MHz. The Free Watchdog Timer
has independent clock source (IRC32K), and Real Time Clock (RTC) uses t he IRC32K,
LXTAL or HXTAL divided by RTCDIV (in RCU_CFG0 register) as its clock source.