EXTI internal peripheral

Applicable for

STM32MP13x lines, STM32MP15x lines, STM32MP25x lines

Warning

Concerning the STM32MP25x lines , only the boot time assignment table and the runtime assignment table have been updated.
The other chapters have not been updated yet.

1. Article purpose[edit source]

The purpose of this article is to:

briefly introduce the EXTI peripheral and its main features,
indicate the peripheral instances assignment at boot time and their assignment at runtime (including whether instances can be allocated to secure contexts),
list the software frameworks and drivers managing the peripheral,
explain how to configure the peripheral.

2. Peripheral overview[edit source]

The EXTI peripheral is used to get an interrupt when a GPIO is toggling. It can also wake up the system from Stop low power mode, by means of the PWR internal peripheral when a wake up event occurs, before (eventualy - see the note below) propagating an interrupt to the client processor (Cortex-A7 GIC or Cortex-M4 NVIC in case of STM32MP15). The wake up events can be internal (from other IPs clocked by the LSE, LSI or HSI from RCC), or external (from GPIO).

Notice that:

Up to 16 GPIO pins can be configured as external interrupts: for each index between 0 and 15, one EXTI can be selected among all banks (EXTI<index> = GPIO<one_bank><index>).
On STM32MP13x lines : The 16 GPIO and one internal peripheral events ( AVD/PVD), can generate interrupts connected to the GIC. All the other internal peripheral events can wake up the system, but the EXTI does not generate any interrupt to the GIC; in such cases, another peripheral interrupt has to be used as a trigger via the GIC.
On STM32MP15x lines : The 16 GPIO and 5 internal peripheral events (AVD/PVD, CPU1 SEV, CPU2 SEV, WWDG1 reset, CPU2 SYSRESETREQ) can generate interrupts connected to the GIC and NVIC. All the other internal peripheral events can wake up the system, but the EXTI does not generate any interrupt to the GIC or NVIC for them; in such cases, another peripheral interrupt has to be used as a trigger via the GIC or NVIC.
By default, at reset, all EXTI wake up events are non-secure.

Refer to the STM32 MPU reference manuals for the complete list of features, and to the software frameworks and drivers, introduced below, to see which features are implemented.

3. Peripheral usage[edit source]

This chapter is applicable in the scope of the OpenSTLinux BSP running on the Arm^® Cortex^®-A processor(s), and the STM32CubeMPU Package running on the Arm^® Cortex^®-M processor.

3.1. Boot time assignment[edit source]

3.1.1. On STM32MP15x lines [edit source]

The EXTI peripheral is not used at boot time, but is configured during Linux initialization.

Since wake-up event configuration is done via register bit-field reads and writes, concurrent accesses from Linux and the coprocessor are not possible at boot time:

Linux configures all EXTI events during their respective consumer driver probing
The coprocessor uses the resource management mechanisms to request and configure the EXTI events it needs.

3.1.2. On STM32MP2 series[edit source]

Click on to expand or collapse the legend...

☐ means that the peripheral can be assigned to the given boot time context.
☑ means that the peripheral is assigned by default to the given boot time context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
⬚ means that the peripheral can be assigned to the given boot time context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP25 reference manuals.

Domain	Peripheral	Boot time allocation				Comment
Domain	Peripheral	Instance	Cortex-A35 secure (ROM code)	Cortex-A35 secure (TF-A BL2)	Cortex-A35 non-secure (U-Boot)	Comment
Core/Interrupts	EXTI	EXTI1	☐	☐	☐	Shareable at internal peripheral level thanks to the RIF: see the boot time allocation per feature
Core/Interrupts	EXTI	EXTI2	☐	☐	☐	Shareable at internal peripheral level thanks to the RIF: see the boot time allocation per feature

The below table shows the possible boot time allocations for the features of the EXTI1 instance.

Feature	Boot time allocation			Comment
Feature	Cortex-A35 secure (ROM code)	Cortex-A35 secure (TF-A BL2)	Cortex-A35 non-secure (U-Boot)	Comment
EXTI1[0]			⬚
EXTI1[1]			⬚
EXTI1[2]			⬚
EXTI1[3]			⬚
EXTI1[4]			⬚
EXTI1[5]			⬚
EXTI1[6]			⬚
EXTI1[7]			⬚
EXTI1[8]			⬚
EXTI1[9]			⬚
EXTI1[10]			⬚
EXTI1[11]			⬚
EXTI1[12]			⬚
EXTI1[13]			⬚
EXTI1[14]			⬚
EXTI1[15]			⬚
PVD			⬚
PVM			⬚
VDDGPU_VD			⬚
RCC_HSI_FMON			⬚
I2C1			⬚
I2C2			⬚
I2C3			⬚
I2C4			⬚
I2C5			⬚
USART1			⬚
USART2			⬚
USART3			⬚
USART6			⬚
UART4			⬚
UART5			⬚
UART7			⬚
UART8			⬚
UART9			⬚
SPI1			⬚
SPI2			⬚
SPI3			⬚
SPI4			⬚
SPI5			⬚
SPI6			⬚
SPI7			⬚
USBH			⬚
USB3DR			⬚
COMBOPHY			⬚
UCPD			⬚
LPTIM1			⬚
LPTIM2			⬚
I2C6			⬚
I2C7			⬚
WKUP1 wakeup			⬚
WKUP2 wakeup			⬚
WKUP3 wakeup			⬚
WKUP4 wakeup			⬚
WKUP5 wakeup			⬚
WKUP6 wakeup			⬚
IPCC1 non secure interrupt CPU1			⬚
IPCC1 non secure interrupt CPU2
IPCC1 secure interrupt CPU1
IPCC1 secure interrupt CPU2
CPU2 SEV interrupt			⬚
CPU1 SEV interrupt
WWDG1 Reset			⬚
ETH1_PMT wakeup			⬚
ETH1_SBD			⬚
ETH2_PMT wakeup			⬚
ETH2_SBD			⬚
DTS			⬚
CPU2 SYSRESETREQ local CPU2 reset
I3C1
I3C2
I3C3
HPDMA1 Channel 0 to 15 CPU1 irq			⬚
HPDMA2 Channel 0 to 15 CPU1 irq			⬚
HPDMA3 Channel 0 to 15 CPU1 irq			⬚
HPDMA1 Channel 0 to 15 CPU2 irq
HPDMA2 Channel 0 to 15 CPU2 irq
HPDMA3 Channel 0 to 15 CPU2 irq
UCPD VBUS DETECT			⬚
UCPD VBUS VSAFE5V			⬚

The below table shows the possible boot time allocations for the features of the EXTI2 instance.

Feature	Boot time allocation			Comment
Feature	Cortex-A35 secure (ROM code)	Cortex-A35 secure (TF-A BL2)	Cortex-A35 non-secure (U-Boot)	Comment
EXTI2[0]			⬚
EXTI2[1]			⬚
EXTI2[2]			⬚
EXTI2[3]			⬚
EXTI2[4]			⬚
EXTI2[5]			⬚
EXTI2[6]			⬚
EXTI2[7]			⬚
EXTI2[8]			⬚
EXTI2[9]			⬚
EXTI2[10]			⬚
EXTI2[11]			⬚
EXTI2[12]			⬚
EXTI2[13]			⬚
EXTI2[14]			⬚
EXTI2[15]			⬚
TAMP non secure tamper CPU1			⬚
RTC global non secure Wakeup CPU1			⬚
TAMP non secure tamper CPU2
RTC global non secure Wakeup CPU2
TAMP non secure tamper CPU3
TAMP secure tamper CPU1
RTC global secure Wakeup CPU1
TAMP secure tamper CPU2
RTC global secure Wakeup CPU2
I2C8			⬚
LPUART1			⬚
SPI8			⬚
LPTIM3			⬚
LPTIM4			⬚
LPTIM5			⬚
ADF1			⬚
IPCC2 non secure interrupt CPU1			⬚
IPCC2 non secure interrupt CPU2
IPCC2 non secure interrupt CPU3
IPCC2 secure interrupt CPU1
IPCC2 secure interrupt CPU2
HSEM1 non secure interrupt			⬚
HSEM2 non secure interrupt
HSEM3 non secure interrupt
HSEM1 secure interrupt
HSEM2 secure interrupt
WWDG2 reset			⬚
IWDG1 reset
IWDG2 reset
IWDG3 reset			⬚
IWDG4 reset			⬚
IWDG5 reset			⬚
IWDG1 early wake			⬚
IWDG2 early wake			⬚
IWDG3 early wake
IWDG4 early wake
IWDG5 early wake
CM33 SEV interrupt to CPU3
CA35 SEV interrupt to CPU3
CM0 SEV interrupt			⬚
IAC interrupt CPU1
IAC interrupt CPU2
VDDCPU_VD			⬚
VDDCORE_VD			⬚
RETRAM CRC error wakeup
lpdma_ch0123_cpu1_irq			⬚
lpdma_ch0123_cpu2_irq
lpdma_ch0123_cpu3_irq
I3C4			⬚
CDBGPWRUPREQ			⬚

3.2. Runtime assignment[edit source]

3.2.1. On STM32MP13x lines [edit source]

Click on to expand or collapse the legend...

STM32MP13 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

☐ means that the peripheral can be assigned to the given runtime context.
☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP13 reference manuals.

Domain	Peripheral	Runtime allocation			Comment
Domain	Peripheral	Instance	Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)	Comment
Core/Interrupts	EXTI	EXTI	☐	☐

3.2.2. On STM32MP15x lines [edit source]

Click on to expand or collapse the legend...

STM32MP15 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

☐ means that the peripheral can be assigned to the given runtime context.
☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP15 reference manuals.

Domain	Peripheral	Runtime allocation				Comment
Domain	Peripheral	Instance	Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)	Cortex-M4 (STM32Cube)	Comment
Core/Interrupts	EXTI	EXTI	☐	☐	☐	Shared

Information

The EXTI peripheral is not listed in STM32CubeMX peripherals list because its configuration is partly embedded in the Device tree (for all internal EXTI sources, coming from peripherals with wake up capabilities) and completed with the GPIO configuration that comes from STM32CubeMX pinout view

The OP-TEE EXTI driver is not activated and not used by OpenSTLinux on STM32MP15x lines .

3.2.3. On STM32MP25x lines [edit source]

Click on to expand or collapse the legend...

STM32MP25 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

☐ means that the peripheral can be assigned to the given runtime context.
☑ means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
⬚ means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
✓ is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP25 reference manuals.

Domain	Peripheral	Runtime allocation						Comment
Domain	Peripheral	Instance	Cortex-A35 secure (OP-TEE / TF-A BL31)	Cortex-A35 non-secure (Linux)	Cortex-M33 secure (TF-M)	Cortex-M33 non-secure (STM32Cube)	Cortex-M0+ (STM32Cube)	Comment
Core/Interrupts	EXTI	EXTI1	☐^OP-TEE	☐	☐	☐	☐	Shareable at internal peripheral level thanks to the RIF: see the runtime allocation per feature
Core/Interrupts	EXTI	EXTI2	☐^OP-TEE	☐	☐	☐	☐	Shareable at internal peripheral level thanks to the RIF: see the runtime allocation per feature

The below table shows the possible runtime allocations for the features of the EXTI1 instance.

Feature	Runtime allocation					Comment
Feature	Cortex-A35 secure (OP-TEE / TF-A BL31)	Cortex-A35 non-secure (Linux)	Cortex-M33 secure (TF-M)	Cortex-M33 non-secure (STM32Cube)	Cortex-M0+ (STM32Cube)	Comment
EXTI1[0]	☐^OP-TEE	☐	☐	☐
EXTI1[1]	☐^OP-TEE	☐	☐	☐
EXTI1[2]	☐^OP-TEE	☐	☐	☐
EXTI1[3]	☐^OP-TEE	☐	☐	☐
EXTI1[4]	☐^OP-TEE	☐	☐	☐
EXTI1[5]	☐^OP-TEE	☐	☐	☐
EXTI1[6]	☐^OP-TEE	☐	☐	☐
EXTI1[7]	☐^OP-TEE	☐	☐	☐
EXTI1[8]	☐^OP-TEE	☐	☐	☐
EXTI1[9]	☐^OP-TEE	☐	☐	☐
EXTI1[10]	☐^OP-TEE	☐	☐	☐
EXTI1[11]	☐^OP-TEE	☐	☐	☐
EXTI1[12]	☐^OP-TEE	☐	☐	☐
EXTI1[13]	☐^OP-TEE	☐	☐	☐
EXTI1[14]	☐^OP-TEE	☐	☐	☐
EXTI1[15]	☐^OP-TEE	☐	☐	☐
PVD	☑^OP-TEE	⬚	☐	⬚
PVM	☑^OP-TEE	⬚	☐	⬚
VDDGPU_VD	☑^OP-TEE	⬚	⬚	⬚
RCC_HSI_FMON	☑^OP-TEE	⬚	☐	⬚
I2C1	☐^OP-TEE	☐	☐	☐
I2C2	☐^OP-TEE	☐	☐	☐
I2C3	☐^OP-TEE	☐	☐	☐
I2C4	☐^OP-TEE	☐	☐	☐
I2C5	☐^OP-TEE	☐	☐	☐
USART1	☐^OP-TEE	☐	☐	☐
USART2	☐^OP-TEE	☐	☐	☐
USART3	☐^OP-TEE	☐	☐	☐
USART6	☐^OP-TEE	☐	☐	☐
UART4	☐^OP-TEE	☐	☐	☐
UART5	☐^OP-TEE	☐	☐	☐
UART7	☐^OP-TEE	☐	☐	☐
UART8	☐^OP-TEE	☐	☐	☐
UART9	☐^OP-TEE	☐	☐	☐
SPI1	☐^OP-TEE	☐	☐	☐
SPI2	☐^OP-TEE	☐	☐	☐
SPI3	☐^OP-TEE	☐	☐	☐
SPI4	☐^OP-TEE	☐	☐	☐
SPI5	☐^OP-TEE	☐	☐	☐
SPI6	☐^OP-TEE	☐	☐	☐
SPI7	☐^OP-TEE	☐	☐	☐
USBH	⬚^OP-TEE	☐	☐	☐
USB3DR	⬚^OP-TEE	☐	☐	☐
COMBOPHY	⬚^OP-TEE	☑	⬚	⬚
UCPD	⬚^OP-TEE	⬚	⬚	☑
LPTIM1	☐^OP-TEE	☐	☐	☐
LPTIM2	☐^OP-TEE	☐	☐	☐
I2C6	☐^OP-TEE	☐	☐	☐
I2C7	☐^OP-TEE	☐	☐	☐
WKUP1 wakeup	☐^OP-TEE	☐	☐	☐
WKUP2 wakeup	☐^OP-TEE	☐	☐	☐
WKUP3 wakeup	☐^OP-TEE	☐	☐	☐
WKUP4 wakeup	☐^OP-TEE	☐	☐	☐
WKUP5 wakeup	☐^OP-TEE	☐	☐	☐
WKUP6 wakeup	☐^OP-TEE	☐	☐	☐
IPCC1 non secure interrupt CPU1		✓
IPCC1 non secure interrupt CPU2				✓
IPCC1 secure interrupt CPU1	✓^OP-TEE
IPCC1 secure interrupt CPU2			✓
CPU2 SEV interrupt	☐^OP-TEE	☐
CPU1 SEV interrupt			☐	☐
WWDG1 Reset	⬚^OP-TEE	☐
ETH1_PMT wakeup	⬚^OP-TEE	☐	⬚	☐
ETH1_SBD	⬚^OP-TEE	☐	⬚	☐
ETH2_PMT wakeup	⬚^OP-TEE	☐	⬚	☐
ETH2_SBD	⬚^OP-TEE	☐	⬚	☐
DTS	☐^OP-TEE	⬚	☐	⬚
CPU2 SYSRESETREQ local CPU2 reset
I3C1	☐^OP-TEE	☐	☐	☐
I3C2	☐^OP-TEE	☐	☐	☐
I3C3	☐^OP-TEE	☐	☐	☐
HPDMA1 Channel 0 to 15 CPU1 irq	☐^OP-TEE	☐
HPDMA2 Channel 0 to 15 CPU1 irq	☐^OP-TEE	☐
HPDMA3 Channel 0 to 15 CPU1 irq	☐^OP-TEE	☐
HPDMA1 Channel 0 to 15 CPU2 irq			☐	☐
HPDMA2 Channel 0 to 15 CPU2 irq			☐	☐
HPDMA3 Channel 0 to 15 CPU2 irq			☐	☐
UCPD VBUS DETECT	⬚^OP-TEE	⬚	⬚	☑
UCPD VBUS VSAFE5V	⬚^OP-TEE	⬚	⬚	☑

The below table shows the possible runtime allocations for the features of the EXTI2 instance.

Feature	Runtime allocation					Comment
Feature	Cortex-A35 secure (OP-TEE / TF-A BL31)	Cortex-A35 non-secure (Linux)	Cortex-M33 secure (TF-M)	Cortex-M33 non-secure (STM32Cube)	Cortex-M0+ (STM32Cube)	Comment
EXTI2[0]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[1]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[2]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[3]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[4]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[5]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[6]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[7]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[8]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[9]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[10]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[11]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[12]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[13]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[14]	☐^OP-TEE	☐	☐	☐	☐
EXTI2[15]	☐^OP-TEE	☐	☐	☐
TAMP non secure tamper CPU1		⬚
RTC global non secure Wakeup CPU1		✓
TAMP non secure tamper CPU2				☐
RTC global non secure Wakeup CPU2				☐
TAMP non secure tamper CPU3					☐
TAMP secure tamper CPU1	✓^OP-TEE
RTC global secure Wakeup CPU1	✓^OP-TEE
TAMP secure tamper CPU2			☐
RTC global secure Wakeup CPU2			☐
I2C8	☐^OP-TEE	☐	☐	☐	☐
LPUART1	☐^OP-TEE	☐	☐	☐	☐
SPI8	☐^OP-TEE	☐	☐	☐	☐
LPTIM3	☐^OP-TEE	☐	☐	☐	☐
LPTIM4	☐^OP-TEE	☐	☐	☐	☐
LPTIM5	☐^OP-TEE	☐	☐	☐	☐
ADF1	☐^OP-TEE	☐	☐	☐	☐
IPCC2 non secure interrupt CPU1		☑
IPCC2 non secure interrupt CPU2				☑
IPCC2 non secure interrupt CPU3					☑
IPCC2 secure interrupt CPU1	☑^OP-TEE
IPCC2 secure interrupt CPU2			☑
HSEM1 non secure interrupt		☑
HSEM2 non secure interrupt				☑
HSEM3 non secure interrupt					☑
HSEM1 secure interrupt	☑^OP-TEE
HSEM2 secure interrupt			☑
WWDG2 reset	☐^OP-TEE	☐	☐	☐
IWDG1 reset
IWDG2 reset	☑^OP-TEE		☐	☐
IWDG3 reset	☐^OP-TEE	☐
IWDG4 reset	☐^OP-TEE	☐	☑
IWDG5 reset	☐^OP-TEE	☐	☐	☐
IWDG1 early wake	☑^OP-TEE	☐
IWDG2 early wake	☐^OP-TEE	☑
IWDG3 early wake			☑	☐
IWDG4 early wake			☐	☑
IWDG5 early wake					☑
CM33 SEV interrupt to CPU3					☑
CA35 SEV interrupt to CPU3					☑
CM0 SEV interrupt	☐^OP-TEE	☐	☐	☐
IAC interrupt CPU1	✓^OP-TEE
IAC interrupt CPU2
VDDCPU_VD	☐^OP-TEE	⬚	☐	☐
VDDCORE_VD	☐^OP-TEE	⬚	☐	☐	☐
RETRAM CRC error wakeup
lpdma_ch0123_cpu1_irq	⬚^OP-TEE	⬚
lpdma_ch0123_cpu2_irq			☐	☐
lpdma_ch0123_cpu3_irq					☐
I3C4	☐^OP-TEE	☐	☐	☐	☐
CDBGPWRUPREQ	☐^OP-TEE	☐	☐	☐	☐

4. Software frameworks and drivers[edit source]

Below are listed the software frameworks and drivers managing the EXTI peripheral for the embedded software components listed in the above tables.

Linux^®: interrupts framework
OP-TEE: OP-TEE EXTI driver
STM32Cube: HAL EXTI driver

5. How to assign and configure the peripheral[edit source]

The peripheral assignment can be done via the STM32CubeMX graphical tool (and manually completed if needed).
This tool also helps to configure the peripheral:

partial device trees (pin control and clock tree) generation for the OpenSTLinux software components,
HAL initialization code generation for the STM32CubeMPU Package.

The configuration is applied by the firmware running in the context in which the peripheral is assigned.

See also additional information in the Interrupt device tree configuration article for Linux^®.