STM32H7 DMA memory to GPIO port

[Peter Mather]

Has anyone got working example code they could share of setting up DMA to transfer from memory to a GPIO port on an H7 (Nucleo-H743). I've read AN4666 and can get the example working on a L476 but none of the many variants I try on the H7 work. The example could use a timer to clock the transfer or just free-run. The application will have an area of memory that is continuously transferred to the GPIO port with the DMA in circular mode.

Many thanks in anticipation

[Imen.D]

Hello @Community member​ 

Did you tried the available DMA example of CubeH7 v1.3.2? Did you followed the instructions in readme file ? Did you enabled the cache? and waht about the MPU configuration?

Kind Regards,

Imen

[JGon?]

I'm also having trouble with the DMA.

I wanted to send a 8bit array from the SRAM to 8 pin GPIO at 25 MHZ/ 12.5 MHZ speed using the DMA controlled by a timer as an University project.

I bought a STM32H743 (NUCLEO) due to it's power and extra memory.

Since I'm new to the STM32 architecture, I was expecting it to be as easy as the arduino (the only MCU that I worked with in a register level) and I was expecting to find a lot of resources on the internet. That was my mistake.

The only example that I found that addresses this idea was written to the STM32F4 platform (I put it as an attachment) and I don't know how to convert it to the STM32H7 MCU.

Since I can't find any example for this model (after looking for weeks), I'm now regretting buying this board and I think I'm going to change to the arduino Due (unfortunately).

Sorry about getting things off my chest like that but I think I'm going crazy with this project/board.

[Tesla DeLorean]

>>I was expecting to find a lot of resources on the internet...

>>Since I can't find any example for this model..

You know that people have to write the stuff that's on the internets and embedded sw engineering is frequently not a task that relies on cutting-n-pasting code Google happens upon, but one that requires connecting a bunch of dots from often vague documentation.

The GPIO banks are on AHB4, use BDMA to copy data from SRAM4 to GPIOx>BSRR or ODR

SRAM4 is 64KB situated at 0x38000000

Should be able to use LPTIM2 or LPTIM3 OUT as a clocking/triggering source

Figure a couple hours of time to code/validate a working proof.

[flyer31]

This can be done nicely with BDMA, but it works also nicely with DMA.

See my STM32H7 forum post "Parallel transmission using GPIO and DMA (like AN4666)"