TMS320C6657: PLL can not setup

Feng Dong

Intellectual 550 points

Part Number: TMS320C6657

Tool/software:

Hello Guys,

i need your help, it took me a long long time

i had a cunstom board

1 the Init_PLL() code in GEL file is the same

/* part of 8, go stat bit needs to be zero here */
/* Read the GOSTAT bit in PLLSTAT to make sure the bit returns to 0 to *
* indicate that the GO operation has completed */
/* wait for the GOSTAT, but don't trap if lock is never read */
for (i = 0; i < 1000; i++)
{
if ( (PLL1_STAT & 0x00000001) == 0 ) {
break;
}
}
if ( i == 1000 ) {
GEL_TextOut ( "Error while waiting for GOSTAT bit returning to 0 ... \n");
return(-1);
}

---------we are wrong here , PLL1_STAT is 5

2 . sysclkout is about 16.8M Hz

is the board's hardware ok?

what's wrong

thanks , i need your suggestion

11 months ago

0 Shankari G 11 months ago

TI__Mastermind 25535 points

Feng,

1. Run the gel file on TI -C6657 EVM and check the value of PLL1_STAT. Compare the gel outputs with your custom board results.

2. The SYSCLKOUT always comes from SYSCLK1/6.

If the DSP core frequency is 1000 MHz ---> then, 1000 ÷ 6 = 166.66 MHz.

====> SYSCLKOUT would be 166.66 MHz if the core frequency is 1000MHz.

---

PLEASE NOTE , sysclkout cannot be 16.8 MHz

Because even the least operating core frequency of C665x is 850MHz.

so, 850 / 6 = 141.66 MHz --> SYSCLKOUT

Regards

Shankari G

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TMS320C6657: PLL can not setup