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Rev. 1.00
116 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
7 Reset Control Unit (RSTCU)
PORRESETn
SYSRESETn
V
DD33
V
CORE
t
1
t
2
t
3
t
1
= 25
μ
s *Typical.
t
2
= 100
μ
s
t
3
= 150
μ
s
* This timing is dependent on the internal LDO regulator output capacitor value.
Figure 21. Power-On Reset Sequence
System Reset
A system reset is generated by a power-on reset (PORRESETn), a Watchdog Timer reset (WDT_
RSTn), an nRST pin event or a software reset (SYSRESETREQ) event. For more information about
SYSRESETREQ event, refer to the related chapter in the Cortex
®
-M0+ reference manual.
AHB and APB Unit Reset
The AHB and APB unit reset can be divided into hardware and software resets. A hardware
reset can be generated by either power on reset or system reset for all AHB and APB units.
Each functional IP connected to the AHB and APB buses can be reset individually through the
associated software reset bits in the RSTCU. For example, the application software can generate a
UART0 reset via the UR0RST bit in the APBPRSTR0 register.
Register Map
The following table shows the RSTCU registers and reset values.
Table 20. RSTCU Register Map
Register
Offset
Description
Reset Value
GRSR
0x100
Global Reset Status Register
0x0000_0008
AHBPRSTR
0x104
AHB Peripheral Reset Register
0x0000_0000
APBPRSTR0
0x108
APB Peripheral Reset Register 0
0x0000_0000
APBPRSTR1
0x10C
APB Peripheral Reset Register 1
0x0000_0000