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Altera_Forum's avatar
Altera_Forum
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18 years ago

different between sdram and ddr sdram?

:eek:

Hi everyone,

I'm a newbee in FPGA, so maybe my question is funny. But i want to know are there sth different between ddr sdram and sdram. I have a DSP dev kit 2s60, i see in the manual there are only sdrams, can i use ddr sdram core on it?

2 Replies

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

    Hello Ding-10100

    SDRAM and DDR SDRAM differ in that the Double Data Rate (DDR) SDRAM take in and put out data on both the rising and falling edge of the clock signal. (Thus the name Double data rate). This gives the benefit of moving twice as much data between the (in this case) FPGA and the Memory device. Once inside the FPGA, the data has to be captured (on both the rising and falling edges), then re-captured back onto (typically) the rising edge of an internal clock (usually also doubling the width of the data internal to the FPGA) so that the data can be worked on, or sent to toher modules in the FPGA, etc.

    Therefore, you can NOT use a DDR SDRAM controller core with SDRAM (SDR SDRAM - Single Data Rate - SDRAM) and visa-a-versa.

    I hopet his helps, welcome to the family.

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