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Rev. 1.00
169 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
9
Alternate Function Input/Output Control Unit (AFIO)
9
Alternate Function Input/Output Control Unit (AFIO)
Features
▆
APB slave interface for register access
▆
EXTI source selection
▆
Configurable pin function for each GPIO, up to sixteen alternative functions on each pin
▆
AFIO lock mechanism
Functional Descriptions
External Interrupt Pin Selection
The GPIO pins are connected to the 16 EXTI lines as shown in the accompanying figure. For
example, the user can set the EXTI0PIN [3:0] field in the ESSR0 register to b0000 to select the
GPIO PA0 pin as EXTI line 0 input. Since not all the pins of the Port A ~ D are available in all
package types, refer to the pin assignment section for detailed pin information. The setting of the
EXTInPIN [3:0] field is invalid when the corresponding pin is not available.
0000
0001
0010
0011
PA0
PB0
EXTIx Pin Selection
EXTI0PIN[3:0]
EXTI 0
EXTI15PIN[3:0]
PC0
PD0
EXTI 15
PB15
PC15
PD15
PA15
0000
0001
0010
0011
Figure 25. EXTI Channel Input Selection