External Interrupt / Event Line Mapping; Interrupt And Debounce; Figure 25. Exti Interrupt Debounce Function - Holtek HT32F50231 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F50231/HT32F50241

External Interrupt / Event Line Mapping

All GPIO pins can be selected as EXTI trigger sources by configuring the EXTInPIN [3:0] field in
the AFIO ESSRn (n = 0 ~ 1) register to trigger an interrupt or event. Refer to the AFIO section for
more details.

Interrupt and Debounce

The application software can set the DBnEN bit in the EXTIn Interrupt Configuration Register
EXTICFGRn (n = 0 ~ 15) to enable the corresponding pin de-bounce function and configure
the DBnCNT field in the EXTICFGRn so as to select an appropriate debounce time for specific
applications. The interrupt signal will however be delayed due to the de-bounce function. When
the device is woken up from the power saving mode by an external interrupt, an interrupt request
will be generated by the EXTI wakeup flag. After the device has been woken up and the clock has
recovered, the EXTI wakeup flag that was triggered by the EXTI line must be read and then cleared
by application software. The accompanying diagram shows the relationship between the EXTI
input signal and the EXTI interrupt / event request signal.
EXTIn Pin Input
EXTIn Interrupt Request

Figure 25. EXTI Interrupt Debounce Function

Rev. 1.00
Low pulse is
shorter than
debounce time
Debounce
time delay
151 of 486 July 31, 2018