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How to explain the address 0x02004000 for NAND Chip Select 1 using A12

ruqun xu
Intellectual 990 points

In the DM355 EVM,the Flash is MT29F16G08.The  address of ASYNC EMIF (Data)  is from 0x02000000 to 0x09ffffff.

So the NAND chip select 0 flash address is 0x02000000.I can understand this .

But ,the NAND Chip Select 1 flash address is 0x02004000,and the pin A12 is linked to CE2 of  NAND FLASH.

What is the meaning of 0x02004000 and the A12 ?

Why the address is not 0x02005000?

Because ,I will change the flash ,so I want to know  it clearly.

  • 0
    TI__Mastermind 41665 points

    The address line A12 is the 13th address line on the AEMIF interface (0:12), so to have it be asserted you need to access an address of 2^13 0r 0x2000, however this is just assuming 8 bit operation, if the AEMIF is configured for 16 bit than you would need to access an address from the internal point of view of 2x this or 0x4000, as it will take two internal address increments (in bytes) for each increment of the AEMIF address bus (in 16 bit words). Essentially, if your AEMIF is configured for 16 bit than to assert A12 you would need to access the address starting at 0x02004000.

    I am not sure where you are getting 0x02005000 from?

  • 0 in reply to Bernie Thompson TI
    Intellectual 990 points

    Thanks for your help.In TI EVM the flash is MT29F16G08 of 8-bit bus.

    A1:0x02000008;

    A2:0x02000010;

    A12: 0x02004000;

    Can I use other pin to connect the cs2 of nand flash instead of A12  ,such as A13 : 0x02008000?

    If I can ,what do I have to do this in the software of u-boot or kernel?

     

  • 0 in reply to ruqun xu
    TI__Mastermind 41665 points

    I suppose you could use another pin, it would just effect what addresses end up being used to send commands to the NAND, since the ROM boot loader is only using the first CE anyway you would just have to modify UBL, U-Boot, and the kernel NAND driver to take this into account. You would have to search through the source and change any reference to the second chip enable to use the new address for asserting the CS2 of the flash, this could end up being as easy as just making a header file change for the new address, but I could not say for certain as I have not done such a modification.