Stm32 h7

[SDall]

hi I wanted to ask regarding stm32h7 as I have two main available one for m4 main and the other for m7 main, if I process a variable in the cortex m4 how can I transfer it to the m7?

Can i use mdma or dma.....

Tanks​

[Rainer1]

There are several examples in the STM32H7 Cube FW in the H745 folders, where this scenario is used.

In general:

• Place the shared variables in a SRAM region accessible by both cores, i.e. SRAM1 - 4
• guarantee cache integrity for the CM7, the easiest way to do this is excluding the memory area from dcache by setting up a corresponding MMU section
• guard the access by a HSEM semaphore

[Rainer1]

Here are two of the example projects dealing with shared memory:

https://github.com/STMicroelectronics/STM32CubeH7/tree/master/Projects/NUCLEO-H745ZI-Q/Applications/FreeRTOS

[Tesla DeLorean]

The two cores don't understand the variables in the other. Each core has code compiled and linked independently.

Determine what information you are passing or sharing, and encapsulate that in a structure with the same form, and at address space visible to both cores. Pointers can be used to set the structure address.​

[RMcCa]

You can also use the MDMA. The m4 core can initiate an mdma block transfer which can then cause a transfer complete interrupt on the m7. No cache problems, just make sure the m4 knows the destination address somehow.​