Texas Instruments TMS320DM643x manual Device Clock Generation, System PLLC1 Output Clocks

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PLL1 Control

CLKMODE

CLKIN 1

OSCIN 0

Figure 5-1. PLL1 Structure in the TMS320DM643x DMP

	PLLEN
PLLOUT	PLLDIV1￿(/1)	SYSCLK1
		(CLKDIV1￿Domain)
PLL
	1	SYSCLK2
	PLLDIV2￿(/3)
		(CLKDIV3￿Domain)
	0	SYSCLK3
	PLLDIV3￿(/6)
PLLM		(CLKDIV6￿Domain)
		AUXCLK
		(CLKIN￿Domain)
		SYSCLKBP
BPDIV		(VPSS-VPBR
		Clock￿Source)
OSCDIV1		OBSCLK
		(CLKOUT0￿Pin)

5.2.1 Device Clock Generation

PLLC1 generates several clocks from the PLL1 output clock for use by the various processors and modules. These are summarized in Table 5-1. SYSCLK1, SYSCLK2, and SYSCLK3 must maintain a fixed frequency ratio requirement, no matter what reference clock (PLL or bypass) or PLL frequency is used.

Table 5-1. System PLLC1 Output Clocks

PLLC1 Output Clock	Used by	Default Divider
SYSCLK1	DSP Subsystem	/1
SYSCLK2	SCR, EDMA, VPSS, CLKDIV3 Domain peripherals	/3
SYSCLK3	CLKDIV6 Domain peripherals	/6
AUXCLK	CLKIN Domain peripherals	NA
OBSCLK	CLKOUT0 source	/1
SYSCLKBP	VPBE clock source	/1

5.2.2 Steps for Changing PLL1/Core Domain Frequency

Refer to the appropriate subsection on how to program the PLL1/Core Domain clocks:

∙If the PLL is powered down (PLLPWRDN bit in PLLCTL is set to 1), follow the full PLL initialization procedure in Section 5.2.2.1 to initialize the PLL.

∙If the PLL is not powered down (PLLPWRDN bit in PLLCTL is cleared to 0), follow the sequence in Section 5.2.2.2 to change the PLL multiplier.

∙If the PLL is already running at a desired multiplier and you only want to change the SYSCLK dividers, follow the sequence in Section 5.2.2.3.

Note that the PLL is powered down after the following device-level global resets:

∙Power-on Reset (POR)

∙Warm Reset (RESET)

∙Max Reset

SPRU978E–March 2008 PLL Controller 39

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