Testing STM32F4 EVNETOUT

Environment: STM32F407, IAR 7.4, STM32CubeF4

GPIO configuration code:

GPIO_InitStruct.Pin = GPIO_PIN_10;

GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

GPIO_InitStruct.Pull = GPIO_PULLDOWN;

GPIO_InitStruct.Speed ​​= GPIO_SPEED_HIGH;

GPIO_InitStruct.Alternate = GPIO_AF15_EVENTOUT;

HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

The pulse output uses a function defined in intrinsics.h:

__SETV();

Output waveform:

The sampling rate of the oscilloscope is only this high, estimated to be 1 clock, 1/168M=6ns.

According to the documentation, EVENTOUT is used for synchronization between multiple ARMs. Compared with GPIO output, GPIO requires at least 3 instructions to output a pulse, and there is a delay in accessing the bus. However, EVENTOUT output only uses one SEV instruction, and the pulse is directly controlled by the kernel with minimal delay. However, this pulse is too narrow and cannot meet the width requirements of my application, so I have to use GPIO.

I haven't tested receiving EVENT, but I saw in the code that the pin MODE can be set to:

#define GPIO_MODE_EVT_RISING ((uint32_t)0x10120000) /*!< External Event Mode with Rising edge trigger detection */

#define GPIO_MODE_EVT_FALLING ((uint32_t)0x10220000) /*!< External Event Mode with Falling edge trigger detection */

#define GPIO_MODE_EVT_RISING_FALLING ((uint32_t)0x10320000) /*!< External Event Mode with Rising/Falling edge trigger detection */

The receiver does not treat EVENT as an interrupt, but as a wake-up signal. Refer to PM0214: 2.5.1 Entering sleep mode in the STM32F3 and STM32F4 Series Cortex-M4 programming manual.