i.MXRT685 EVK Octal Flash for Code and PSRAM for data section

[yugandhar421]

Hi,

I am using i.MXRT685 EVK and my application requires more memory for global variables and internal SRAM is not suffcient. I found that EVK has onboard 8MB PSRAM and I thought it can be used for data section. After little study I found that PSRAM connected to FlexSPI port A and Octal flash to port B, both falling in same memory map of size 128MB(starting from 0x08000000).

I am using MCUXpresso IDE and in project's properties -> C/C++ Build -> MCU settings -> Memory details, I am unable to keep an address for external PSRAM because the memory address 0x08000000 already given to flash.

Is it possible to do as I require? If yes, please provide me sample example project.

In SDK examples I didn't find any example with both Flash and external PSRAM, but I found only external ram loader example which is executing from external PSRAM. If I use PSRAM initialization code from mpi_loader_extram_loader project in my application which is configured to use flash memory as code section and internal SRAM as data section, with which memory address I can access external PSRAM? Is there any FlexSPI register to decide starting(base) AHB address for memory device connected?

Thanks,

Yugandhar

[yugandhar421]

Hi,

So, that means Can I access PSRAM directly using memory location with pointer? after init of PSRAM on FlexSPI port A. I am not asking about accessing PSRAM as a secondary memory like NOR Flash, I want to access it with AHB memory address. I want to access both Flash and PSRAM simultaneously with AHB addresses not by writing to FlexSPI registers.

Is it possible as I mentioned above?

[Omar_Anguiano]

The SDK example supports AHB writes/reads, the example has flexspi_hyper_ram_ahbcommand_read_data(), which just uses a memcpy() to read data from the RAM using AHB. 

If you have more questions do not hesitate to ask me.
Best regards,
Omar

[Omar_Anguiano]

Hello
Hope you are well.

You can locate the other memory at the end of the flash. That address range is reserved for memories connected to FlexSPI and is sufficient for both memories on the board.
The SDK contains an example that reads/writes the PSRAM through the FlexSPI interface, you can refer to that examples(flexspi_psram_polling_transfer).

If you have more questions do not hesitate to ask me.
Best regards,
Omar