External memory not working during FLASH (F28335)

Hi Subash,

Could you explain a bit more about the flow for your program? What is the use case of SRAM in this case and how the code/data is getting loaded into SRAM?

I assume you are BOOTING the device from Flash in this case and you have set the BOOTMODE pins appropriately for the same.

Regards,

Vivek Singh

Hi Vivek Singh,

 i just mapped the .ebss section to  external memory. My .cmd file is as follows,

MEMORY
{
PAGE 0:
    BEGINRAM:     origin=0x0, length=0x2
    RAMM0:     origin=0x2, length=0x3fe
    OTP:     origin=0x380400, length=0x400
    FLASH:     origin=0x300000, length=0x3fff6  (On chip FLASH)
    BEGINFLASH:     origin=0x33fff6, length=0x2
    CSM_PWL:     origin=0x3f7ff8, length=0x8
    IQTABLES:     origin=0x3fe000, length=0xb50
    IQTABLES2:     origin=0x3feb50, length=0x8c
    FPUTABLES:     origin=0x3febdc, length=0x6a0
    ROM:     origin=0x3ff27c, length=0xd44
    RESET:     origin=0x3fffc0, length=0x2
    VECTORS:     origin=0x3fffc2, length=0x3e
    //RAML4L7:     origin=0xc000, length=0x4000
    ADC_CAL:     origin=0x380080, length=0x9
    ZONE7P:     origin=0x100000, length=0x40000  (OFF chip SRAM)
PAGE 1:
    RAML0L3:      origin=0x8000, length=0x8000
    RAMM1:     origin=0x400, length=0x400
    ZONE7D:     origin=0x210000, length=0x10000
}
SECTIONS
{
    .vectors:     load = 0x000000000
    .text:     > FLASH, PAGE = 0
    .switch:     > FLASH, PAGE = 0
    .bss:     > RAML0L3, PAGE = 1
    .ebss:     > ZONE7P, PAGE = 0
    .far:     > RAML0L3, PAGE = 1
    .cinit:     > FLASH, PAGE = 0
    .pinit:     > FLASH, PAGE = 0
    .const:     > FLASH, PAGE = 0
    .econst:     > FLASH, PAGE = 0
    .reset:     > RESET, PAGE = 0, TYPE = DSECT
    .data:     > RAML0L3, PAGE = 1
    .cio:     > RAML0L3, PAGE = 1
    .sysmem:     > RAML0L3, PAGE = 1
    .esysmem:     > RAML0L3, PAGE = 1
    .stack:     > RAMM1, PAGE = 1
    .rtdx_text:     > FLASH, PAGE = 0
    .rtdx_data:     > RAML0L3, PAGE = 1
    IQmath:     > FLASH, PAGE = 0
    codestart:     > BEGINFLASH, PAGE = 0
    csmpasswds:     > CSM_PWL, PAGE = 0
    csm_rsvd:     > RAMM0, PAGE = 0
    ramfuncs:     LOAD = FLASH,
        RUN = RAMM0,
        LOAD_START(_RamfuncsLoadStart),
        LOAD_END(_RamfuncsLoadEnd),
        RUN_START(_RamfuncsRunStart),
        PAGE = 0
    .adc_cal:     > ADC_CAL, PAGE = 0 , TYPE = NOLOAD
    IQmathTables:     > IQTABLES, PAGE = 0 , TYPE = NOLOAD
    IQmathTables2:     > IQTABLES2, PAGE = 0 , TYPE = NOLOAD
    FPUmathTables:     > FPUTABLES, PAGE = 0 , TYPE = NOLOAD
}

The corresponding linker file is as follows,

MEMORY CONFIGURATION

         name            origin    length      used     unused   attr    fill
----------------------  --------  ---------  --------  --------  ----  --------
PAGE 0:
  BEGINRAM              00000000   00000002  00000000  00000002  RWIX
  RAMM0                 00000002   000003fe  0000001f  000003df  RWIX
  ZONE7P                00100000   00040000  0003eaaa  00001556  RWIX      (length is within the OFF Chip SRAM)
  FLASH                 00300000   0003fff6  00007437  00038bbf  RWIX              (length is within the On Chip FLASH)
  BEGINFLASH            0033fff6   00000002  00000002  00000000  RWIX
  ADC_CAL               00380080   00000009  00000007  00000002  RWIX
  OTP                   00380400   00000400  00000000  00000400  RWIX
  CSM_PWL               003f7ff8   00000008  00000000  00000008  RWIX
  IQTABLES              003fe000   00000b50  00000000  00000b50  RWIX
  IQTABLES2             003feb50   0000008c  00000000  0000008c  RWIX
  FPUTABLES             003febdc   000006a0  00000000  000006a0  RWIX
  ROM                   003ff27c   00000d44  00000000  00000d44  RWIX
  RESET                 003fffc0   00000002  00000000  00000002  RWIX
  VECTORS               003fffc2   0000003e  00000000  0000003e  RWIX

As you can see the variables sizes are well within the memory. If i run in Debug mode and map the appropriate sections to SRAM, the programming is working fine. If i map the appropriate sections to as FLASH as given above and run in debug mode still it is working. But if i map to FLASH memory and disconnect the emulator it is not working.

It is something to do with initialization of external memory, but i have already initialized the external memory using the InitExtMemIf.asm in DSP2833x_CodeStartBranch.asm. It is nothing to do with the hardware, as it works fine in both SRAM and FLASH programming when i do not use external SRAM. It is something related to initializing the external RAM when the DSP board is disconnected from emulator. Correct me if i am wrong.