[ECOS] AT91SAM7SE with external SDRAM

Chris Zimman czimman@bloomberg.com
Mon Aug 20 12:29:00 GMT 2007


> As soon as SDRAM config has been done at the right place is it enough
to
> change address/size values in mt_arm_at91sam7se512_rom.h/.ldi files so
> that ECOS uses SDRAM ?
> Why not to configure SDRAM in hal_hardware_init that seems to be the
first > C code section called from vectors.S, we don't have any skills
in ARM
> assembly here...

Most of the platforms use a templated setup in hal_platform_setup.h, eg.

packages/hal/arm/at91/[your
platform]/current/include/hal_platform_setup.h

[...]

_InitMemory:
        .long   0x01002529  // 0x01000000, 16MB,  2 cycles  after
transfer, 				    // 16-bit, 6 wait states
        .long   0x02002121  // 0x02000000, 16MB,  0 cycles after
transfer, 				    // 16-bit, 1 wait state
        .long   0x20000000  // unused
        .long   0x30000000  // unused
        .long   0x05002021  // 0x05000000, 1MB,   0 cycles after
transfer, 				    // 16-bit, 1 wait state
(MEC01 on CS4)
        .long   0x05102021  // 0x05100000, 1MB,   0 cycles after
transfer, 				    // 16-bit, 1 wait state
(MEC01 on CS5)
        .long   0x60000000  // unused
        .long   0x70000000  // unused
        .long   0x00000001  // REMAP command
        .long   0x00000000  // Standard read protocol
        .long   AT91_EBI    // External Bus Interface address
        .long   10f         // address where to jump

[...]

Figure out what the correct values for the EBI chip selects are for your
platform and then add them here.

Extensive ARM assembly skills are not required, just a little bit of
reading and perhaps stepping through the setup code with a debugger if
things don't go how you're expecting.

--Chris

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