M4 Memory Regions

[chillercraft]

Hi Octavo,

I recently got my hands on the OSD32MP1-BRK board and I have begun trying to port an M4 based application to it. What I’m having troubles with is the FLASH and Memory region mappings.

a) I see the board has 512MB of DDR3 memory, is that for the A7 and M4 to share or how much of that can the M4 use?
b) Does that 512MB also include what would be considered FLASH for the M4?
c) What are the memory regions for the different memory banks?
d) If 512MB is all the M4 has access to in terms of RAM and FLASH, can it access a block of memory allocated on the SD Card?

Sorry if these are basic questions, this is my first time digging into a microcontroller architecture.

Thanks,
Connor

[Neeraj Dantu]

Connor,

The M4 does not have access to the DDR peripheral, the A7 always controls it. The A7 either at U-boot or after Linux kernel boot can start the M4 co-processor with appropriate firmware. This can be stored in the same non-volatile memory that is used for Linux root filesystem. Please take a look at the memory available for the M4 in section 3.4.2 of the datasheet here: https://www.st.com/resource/en/datasheet/stm32mp157c.pdf and https://wiki.st.com/stm32mpu/wiki/MCU_SRAM_internal_memory.

Other resources you might find useful here:

https://wiki.st.com/stm32mpu/wiki/IPCC_internal_peripheral

https://wiki.st.com/stm32mpu/wiki/Category:Coprocessor_management_Linux

 

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