Externai interupts for I/O pin in OUTPUT

[LVara.1]

I'm using a board Nucleo Stm32F401RE on Stm32Cube 1.8.

A simple question : I have cofigured, in MX, I/O pin PC5 as GPIO_EXT_INT5

with interrupt in falling edge , pull_up enabled and NVIC[9:5] enabled

Remember: in Nucleo board PA5 pin control in OUTPUT a green led on board

Genereting the configuration code I have:

/*Configure GPIO pin : PtPin */

 GPIO_InitStruct.Pin = LD2_Pin;

 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

 HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : PC5 */

 GPIO_InitStruct.Pin = GPIO_PIN_5;

 GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;

 GPIO_InitStruct.Pull = GPIO_PULLUP;

 HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

OK.

In stm32f4xxit.c I have:

void EXTI9_5_IRQHandler(void)

{

 HAL_GPIO_EXTI_IRQHandler(LD2_Pin);

}

WHY LD2_PIN ??? I asked interrupt for GPIO_PIN5 in GPIOC in Falling edge!

many thanks ...

[KnarfB]

The EXTI interrupts don't care about the GPIO port, only about the pin number. LD2_Pin == GPIO_PIN_5 in you case, so the code is not wrong, maybe not plausible.

hth

KnarfB

[Tesla DeLorean]

Did you create the "PtPin" name?

There have been complaints about the tools muddling up pin names/designations.

But what PC5 gets configured with doesn't look problematic for working as an EXTI, the "Output" mode isn't carrying over between individual pin configurations here.

[Pavel A.]

The "PtPin" and inappropriate use of user defined pin names are artifacts of Cube generator.

Already reported several times. Can only hope they fix it soon.

[S.Ma]

Manually configure the pin as non exti, then hack the EXTI hw register to enbale the inrerrupt. I guess it is similar to people who need EXTI on alternare function pins.

[LVara.1]

The correct PtPin was

 /*Configure GPIO pin : PtPin */

 GPIO_InitStruct.Pin = tasto_Pin;

 GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;

 GPIO_InitStruct.Pull = GPIO_PULLUP;

 HAL_GPIO_Init(tasto_GPIO_Port, &GPIO_InitStruct);

Nothing useful in the stm32f4xx_it.c file. This was an example....

Obviously in the real application I had at least 4 output pins which conflicted with EXTI pins. I changed the names in the stm32f4xx_it.c file by hand. But all this wastes a lot of time, especially if you are a teacher, with 20 young people who have some difficulty understanding how interrupts work ..... If you use two EXTI on two pins of the same number, MX obviously reports the conflict . In this case I did not understand which name is chosen. Thanks and good job!!

[Pavel A.]

For the original question (can an output pin be used as EXTI) - no, EXTI pins of course should be input.

Using pins soldered to LEDs does not look as good idea.

[LVara.1]

The pins of a micro can control a signaling LED (not a lighting led), obviously through a resistance of discrete value. All STM Nucleo boards (and also boards from other manufacturers) control one to two LEDs. From data-sheet DocID024738 Rev 10 ,page 92 ".. The GPIOs (general purpose input/outputs) can sink or source up to ±8 mA...."