Holtek HT32 Manualline page 3

Note: Some MCU types allow the condition whereby V
the corresponding datasheet.
Reset
 Power-on reset
The power-on reset, (POR) is generated by an internal reset generator which has an internal filter
to avoid erroneous operation caused by noise. The HT32 MCUs have integrated POR and PDR
circuits. The reset signal is valid when the system is powered on. When V
after a t
normal operation, if V
immediately to prevent the device from malfunctioning at a low voltage. The V
voltage values can be obtained from the V
 System reset
The system reset is generated by the power-on reset PORRESETn, watchdog timer reset
WDT_RSTn, nRST pin, or a software reset SYSRESETREQ event.
 WDT reset
The watchdog timer is a hardware timing circuit that is used to detect a system freeze caused
by a software deadlock. The watchdog timer can work in the reset mode. When the watchdog
counter counts down to the zero, the watchdog timer will generate a reset. Therefore, during
normal operation the software should reload the counter value before the watchdog timer
underflows. In addition, if the software reloads the counter before the counter reaches the
WDT delta value, a reset can also occur. This aims to prevent the software from being stuck
in software areas where the counter is being constantly reloaded. Therefore the counter must
be reloaded during the limited time window where the watchdog timer value is from 0 to
WDTD.
The watchdog timer counter can be stopped when the processor is in the debug or sleep
mode. In order to prevent the watchdog timer configuration from being changed
unexpectedly, the write protection for the register should be enabled.
 Software reset - NVIC Reset
A reset request is sent to the system through the NVIC. Refer to the Cortex
reference manual for more information.
AN0630EN V1.00
HT32 MCU Hardware Development Guideline
time, the reset will be disabled and the MCU will begin to operate normally. During
RSTD
drops below the V
DD
V
DD
V
POR
t
RSTD
RESET
3 / 12
≤V . For details about this, refer to
DDA DD
value, the reset circuit will reset the MCU
PDR
power reset characteristics of the datasheet.
DD
Hysteresis
V
PDR
POR Delay Time
exceeds V and
DD POR
and V
POR PDR
Time
® -M0+ technical
December 15, 2022