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Altera_Forum's avatar
Altera_Forum
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16 years ago

how to get 100Mhz and 27Mhz with only one pll for 2c70

Can we get 100Mhz and 27Mhz with only one pll for 2c70 ?

If can,how?

thank you!

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    You could open quartus and create a new project with the cyclone II EP2C70 fpga.

    then run the wizzard for a new pll and setup plloutput c0 to 100MHz and c1 to 27MHz, now go back and play with the input frequency to see wheter that pll could be implemented or not. the wizzard will tell you that.

    or, have a look at the cyclone II PLL documentation, you can start with this document

    http://www.altera.com/literature/hb/cyc2/cyc2_cii5v1_02.pdf (http://www.altera.com/literature/hb/cyc2/cyc2_cii5v1_02.pdf)
  • Altera_Forum's avatar
    Altera_Forum
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    thank you!

    I know how to use and set pll.

    But according to my setting ,one pll with 50Mhz input only can make 100Mhz and 26.xxMhz clock output.We can not get 27Mhz exactly.

    Can we get 100Mhz and 27Mhz with only one pll for 2c70 ?
  • Altera_Forum's avatar
    Altera_Forum
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    It seems difficult. The pll oscillator would need to run at a very high frequency to manage that.