How to disable/MASK an exti line?

[BZhu.4]

Try to implement an atomtic operation to avoid a specific interrupt generated by GPIOB GPIO_PIN_8 . If using the code as below, it works.

​

HAL_NVIC_DisableIRQ(EXTI9_5_IRQn); 

​

//atomtic operation

​

HAL_NVIC_EnableIRQ(EXTI9_5_IRQn); 

​

But tried the code as following, it doesn't work. Using GPIOB GPIO_PIN_8 as external interrupt.

​

// #define EXTI_LINE_8            (EXTI_GPIO   | 0x08u)  /*!< External interrupt line 8 */

//The value of EXTI_LINE_8 is 0x6000008

​

EXTI->IMR &= ~(EXTI_LINE_8);

​

//atomtic operation 

​

EXTI->IMR |= (EXTI_LINE_8);

//And tried GPIO_PIN_8, it's still not working.

#define GPIO_PIN_8         ((uint16_t)0x0100) /* Pin 8 selected  */

EXTI->IMR &= ~(GPIO_PIN_8);

​

//atomtic operation 

​

EXTI->IMR |= (GPIO_PIN_8);

Any suggetsions?

[KnarfB]

typo, should be |= ?

hth

KnarfB

[BZhu.4]

typo.

But tried the code as following, it doesn't work. Using PB GPIO_PIN_8 as external interrupt.

​

EXTI->IMR &= ~(EXTI_LINE_8);

​

//atomtic operation 

​

EXTI->IMR |= (EXTI_LINE_8);

​ ​

[waclawek.jan]

Which STM32?

> //The value of EXTI_LINE_8 is 0x6000008

> EXTI->IMR &= ~(EXTI_LINE_8);

> EXTI->IMR |= (EXTI_LINE_8);

This of course does not disable and enable EXTI8, but you appear to know that. Don't use the Cube-defined symbols outside Cube's functions for which these symbols are defined.

> it's still not working.

What is "not working"? How exactly do you determine "working" and "non working"?

In 32-bit mcus such as STM32, atomicity - or more precisely, the exact sequencing of events - is extremely complex issue. Here, writing to EXTI_IMR does not disable the interrupt immediately after the processor executes the write, as there are write buffers in the way. In this particular case, reading back the EXTI_IMR after you've written it should ensure that the given value is written after the read instruction is executed by the processor.

JW

[BZhu.4]

Thanks!

​

Tried the code as below: And confirmed IMR value has been changed. It doesn't enable/disable interrupt generated by GPIOB GPIO_PIN_8

/* enable/disable nfc irq */

void set_nfc_irq_callback(u8 enable)

{

u32 value;

​

if(enable)

{

//HAL_NVIC_EnableIRQ(EXTI9_5_IRQn);

/* enable GPIOB GPIO_PIN_8 interrupt */

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

EXTI->PR = (1<<8); 

value = EXTI->IMR;

value |= (1<<8);

EXTI->IMR = value;

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

}

else

{

//HAL_NVIC_DisableIRQ(EXTI9_5_IRQn);

​

/* Don't use the Cube-defined symbols outside Cube's functions for which these symbols are defined. */

//EXTI->IMR &= ~(EXTI_LINE_8);

/* disable GPIOB GPIO_PIN_8 interrupt */

EXTI->PR = (1<<8);

value = EXTI->IMR;

printf("Line: %d, value: %lx\r\n", __LINE__, value);

value &= ~(1<<8);

EXTI->IMR = value;

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

}

}

[S.Ma]

And clear the PR pendimg bit before activate interrupt. Consider also self disabling ISR in case a 100Mhz signal ia maliciously injected on the pin (rugged sw)

[BZhu.4]

Thanks!

​

Tried the code as below: And confirmed IMR value has been changed. It doesn't enable/disable interrupt generated by GPIOB GPIO_PIN_8

/* enable/disable nfc irq */

void set_nfc_irq_callback(u8 enable)

{

u32 value;

​

if(enable)

{

//HAL_NVIC_EnableIRQ(EXTI9_5_IRQn);

/* enable GPIOB GPIO_PIN_8 interrupt */

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

EXTI->PR = (1<<8); 

value = EXTI->IMR;

value |= (1<<8);

EXTI->IMR = value;

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

}

else

{

//HAL_NVIC_DisableIRQ(EXTI9_5_IRQn);

​

/* Don't use the Cube-defined symbols outside Cube's functions for which these symbols are defined. */

//EXTI->IMR &= ~(EXTI_LINE_8);

/* disable GPIOB GPIO_PIN_8 interrupt */

EXTI->PR = (1<<8);

value = EXTI->IMR;

printf("Line: %d, value: %lx\r\n", __LINE__, value);

value &= ~(1<<8);

EXTI->IMR = value;

printf("Line: %d, EXTI->IMR: %lx\r\n", __LINE__, EXTI->IMR);

}

}

[BZhu.4]

What said in last comment is not accuracy. From the logic analyzer, the interrupt pin is always pulled low.

​

If use the ​following code, it's OK.

HAL_NVIC_DisableIRQ(EXTI9_5_IRQn); 

​

//atomtic operation

​

HAL_NVIC_EnableIRQ(EXTI9_5_IRQn);