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Am1802 - Viable EMIF SDRAM Configuration options and performance?

cleidigh
Prodigy 140 points
Other Parts Discussed in Thread: AM1802

I'm looking at the Am1802 SDRAM interface on EMIFA and not clear on a couple items.  We are currently working with an Atmel AT91SAM9260 which has a 32bit SDRAM data bus which we use to connect (2) 256MBit x 16 SDRAMs for a total of 256MBit x 32 memory.  The SDRAM bus is running at 100MHz.   My goal is a similar setup with an AM1802.

 

- EMIF is only 16 bits - does this mean I will have half the performance of an equivalent bus speed 32-bit (2 chip) system such as our current system?

- How would one use (2) SDRAM x16 parts to get to 512Mbit?  I have only found one SDRAM CS (CS0) and single chip diagrams.

- Presumably one 512Mbitx16 is an option, but very costly with few available chips.

 

Thanks

christopher

  • 0
    TI__Guru 64420 points

    The AM1802 has 2 separate external memory interfaces.  The EMIFA supports NOR (8- and 16-bit data), NAND (8- and 16-bit data) and SDRAM (16-bit data).  The DDR2 supports DDR2 (16-bit data) and mDDR (16-bit data).  The EMIFA when supporting SDRAM has a 128MB address space.  The DDR2 supports up to 512MB address space.

    You are correct, the EMIFA only supports 1 SDRAM chip select.

    Is it possible to use DDR2?  This would provide a better overall system performance, as the memory is on a dedicated interface.  It doesn't solve the data width issue, but offsets it a bit with a double-data rate capability.