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Altera_Forum's avatar
Altera_Forum
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14 years ago

About Address & Size of EPCS flash

Dear experts,

I am using Cyclone III with EPCS64 (64Mbits). In SOPCbuilder, I chose "Assign base addresses" and have my epcs_flash_controller configured at base=0x00201800 end=0x00201FFF.

My question:

1) Why the size of memory is only 0x7FF (0x00201FFF - 0x00201800)? Is this less than 64Mbits?

Thank you in advance for the help.

Best regards,

Skw

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    Hi,

    the EPCS controller is the controller for the serial flash. It contains some registers for reading and writing data from and to the serial flash. This is done via serial SPI communication. So you do not need an address space which matches the size oft he flash. The epcs controller also contains 1KB of internal RAM for a bootloader. If properly configured the bootloader copies an application from the serial flash to a memory in the system and jumps to the startaddress of the application.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    HJS,

    Thank you for the reply.

    Do you have any good reference about how to write bootloader to load image from EPCS to external RAM?

    Thanks,

    Skw
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    Skw,

    if you use the simple standard method for loading the fpga configuration and the software from the serial flash you do not have to write yout own bootloader. This is all done automatically. What you have to do is set the cpu reset vector (suppose you are using the nios) to the epcs_flash_controller. And you have convert your software elf file to a flash file which directly start after the fpga configuration in the flash (sof2flash).

    Regards,

    HJS