Read data from the pins to the DMA, via an external interrupt.

[gevmar]

hello everyone, I have a board.STM32F429I DISCO1, the question arose:

is it possible to read  the parallel ,  a 16-bit from port(from the input pins) using some external interrupt (for example, using the rising edge of an external-nterrupt), to the DMA , and how to implement this in cubeMX and stm32cubeide .

Thank you in advance .

[Tesla DeLorean]

Yes, you'd need something on DMA2 (supporting Memory-to-Memory, M2M), so a TIM on APB2, with a TIMx_CHx in Input-Capture mode that can also be mapped as a DMA trigger.

[gevmar]

thanks for the response.
I want to read, say, two bytes of parallel data from port A{15:0}, into the DMA buffer, every time a rising edge of some signal comes to the microcontroller from the outside.

How exactly can this be implemented ?

[Tesla DeLorean]

I'm not the coder on this project. Think of me as the unpaid guy on street giving directions, not a taxi driver to your destination.

I've previously demonstrated and posted how to trigger/capture GPIO via DMA on the F2/F4 but that was in SPL days not HAL.

The GPIO->IDR is 16-bit wide so DMA configured in HALF-WORD mode should suffice into a pattern buffer. The trigger comes via TIM plumbing, described in the Reference Manual, the pins for the TIM in the Data Sheet.

You need to use a TIM on APB2 because only DMA2 allows for memory-to-memory transfers, &GPIOx->IDR is within the broader 4GB address space, on the AHB of the F4, and requires a multi-stage operation rather than piping memory to/from a peripheral internal to APB2 in a direct wired fashion.

[Tesla DeLorean]

The newer H7 designs have a parallel bus method PSSI ? Older designs with synchronous capture, perhaps DCMI but width there is only14-bit. Other than that a latch on the F(S)MC and an EXTI

For classic DREQ implementations, TIM + DMA, Input Capture, One Edge/Both

[gevmar]

Can I in board.STM32F429I DISCO1 , Configure DMA to transfer data from the GPIO port to a memory buffer ?

because I dont see that , in  CubeMX may  support direct GPIO to memory transfer for this use case ?

but can I manually handle this , ? for example 

 

#define BUFFER_SIZE 1

uint16_t dma_buffer[BUFFER_SIZE];

void MX_DMA_Init(void) {

....................................................

DMA_HandleTypeDef hdma;

hdma.Instance = DMA1_Stream0;

hdma.Init.Channel = DMA_CHANNEL_0;

hdma.Init.Direction = DMA_PERIPH_TO_MEMORY;

hdma.Init.PeriphInc = DMA_PINC_DISABLE;

hdma.Init.MemInc = DMA_MINC_ENABLE;

hdma.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;

..................................................................

}

.................................................................................

HAL_DMA_Start(&hdma, (uint32_t)&GPIOA->IDR, (uint32_t)dma_buffer, BUFFER_SIZE);

.........................................................................................................

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin) {

if (GPIO_Pin == GPIO_PIN_0) {         // Assuming PB0 is the EXTI line

Start_DMA(); }

}