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Why there is a PLL Config difference between Romparse and Bootloader　？

xi su
Intellectual 725 points


I  try boot  C6678 by SPI + NOR ， but I found a strange thing .

The input configure  for Romparse   as  below:  

section {
.......
sw_pll_prediv = 5
sw_pll_mult = 32
sw_pll_postdiv = 2
sw_pll_flags = 1
.......
}

But i readed the source code of bootloader , and find the struct of SPI as below :

typedef struct boot_params_spi_s
{
     .......
     UINT16 swPllCfg_msw; /* CPU PLL configuration, MSW */
     UINT16 swPllCfg_lsw; /* CPU PLL configuration, LSW */
     ......
} BOOT_PARAMS_SPI_T;

why the pll config keywords in romparse is sw_pll_prediv but the keywords in bootloader is swPllCfg_msw ?

  • 0
    Intellectual 435 points

    Hi,

    I am also woking with spi&nor boot, and i am quite confused about the parameters prediv, mul and post div. What do these 3 para mean? How shall I drevie the acutal Clock Multiplier Factor from those 3 paras? For example, I successfully boot my c6678 evm with a ddr init para table I found in the form.

    The  para table I found from forum, the 3 field are set as follow:

    00 00 00 00 // pll prediv

    00  00  00  1c// pll mul

    00 00 00 02 // pll postdiv

    And the DDR input clk in C6678 evm is 66.667MHZ, so how do these 3 parameters(mul = 28, div =2 ??) work to derive the

    needed 666.67Mhz ddr rate in EVM? And since I am gonna use spi boot on my own board with ddr input clk 200Mhz, how shall I

    change this 3 parameters to create a 666.67Mhz ddr rate?

    Thanks!

    David Yang