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flexspi memory map for M4 on iMX8-mini

Question asked by Jeff Hane on Jul 30, 2019
Latest reply on Aug 15, 2019 by Jeff Hane

  I need to use the flexspi to talk to an FPGA from the M4.  Currently I'm use the NXP dev board to prototype this by having the M4 read/write data to the connected flash.   From linux, I've written some data the the raw device /dev/mtd0 and can read it back with dd to verify it is correct. 

  Now I just want to memcpy that data and print it on the M4's console; however, it is unclear what the physical address of the flash is.  

 

 There is this info the RM:

 

10.2.4.10 Flash access by AHB Command
Flash could be accessed by AHB bus directly on AHB address space:0~0x10000000.
This address space is mapped to Serial Flash Memory in FlexSPI. AHB bus access to this
address space may trigger Flash access command sequence as needed.

 

The wording this is odd since it sounds like I could access the flash at address 0.   This seems unlikely but I tried reading from address 0 but that data was not what was expected.

 

This table looked promising:

 

2.1.3 Cortex-M4 Memory Map

Start Address    End Address    Region   Size       Allocation
C000_0000       CFFF_FFFF     FLASH   256MB   QSPI

 

Not my data at that address either,  This table has a mapping for QSPI r/w buffers but this is not for AHB which is what I want to use.

 

Anyone know the address from the M4 to access the flash of flexspi??

 

thanks,

jeff

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