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C6678 SPI Boot parameter (nysh.spi.map)

Kzk
Genius 5785 points

Hello,

I'd like to understand the "nysh.spi.map" for SPI boot. I saw the following discussion.
e2e.ti.com/.../394292

I also saw "hwPllSetPll" function.
BootROM_c6678_PG2.0\hw\pll\pll.c

It looks like these parameters are strange. I think CPU clock speed is less than 400MHz.

 sw_pll_prediv = 5
 sw_pll_mult = 32
 sw_pll_postdiv = 2
 sw_pll_flags = 1

ex)
- C6670EVM: 122.88MHz * 32 / 5 / 2 = 393MHz
- C6678EVM: 100MHz * 32 / 5 /2 = 320MHz

I think I should set the following parameters if I hope CPU speed is 1000MHz on C6678EVM. Is my understanding correct?

 sw_pll_prediv = 2 (1+1)
 sw_pll_mult = 40 (39+1)
 sw_pll_postdiv = 2 (1+1)
 sw_pll_flags = 1

Regards,
Kazu

  • 0
    TI__Guru** 116170 points

    Kazu,

    Yes, your understanding is correct. The nysh.map file provided on that forum post was created on a board where the OSCIN =312.5.

    For the EVM that has OSCIN 100Mhz, the multipliers would need to be configured as you specified here:

    Kazu Kon said:
     sw_pll_prediv = 2 (1+1)
     sw_pll_mult = 40 (39+1)
     sw_pll_postdiv = 2 (1+1)
     sw_pll_flags = 1

    This aligns with the table 2-24 provided in the C6678 datasheet.

    Regards,

    Rahul