TMS320VC549 datasheet(38/111 Pages) TI

38 / 111 page

TMS320C54x, TMS320LC54x, TMS320VC54x

FIXED-POINT DIGITAL SIGNAL PROCESSORS

SPRS039C – FEBRUARY 1996 – REVISED DECEMBER 1999

POST OFFICE BOX 1443

• HOUSTON, TEXAS 77251–1443

considerations when using IDLE1/IDLE2/IDLE3 (continued)

STM

#0b, CLKMD

;switch to DIV mode

TstStatu:

LDM

CLKMD, A

AND

#01b, A

;poll STATUS bit

TstStatu, ANEQ

STM

#0b, CLKMD

;reset PLLON_OFF when STATUS

;is DIV mode

IDLE3

(After IDLE3 wake-up – switch the PLL from DIV mode to PLL

3 mode)

STM

#0010001000000111b, CLKMD

;PLLCOUNT = 64 (decimal)

PLL considerations when using the bootloader

The ROM on the ’545A and ’546A contains a bootloader program that can be used to load programs into RAM

for execution following reset. When using this bootloader with the software-programmable PLL, several

considerations are important for proper system operation.

On the ’545A and ’546A, for compatibility, the bootloader configures the PLL to the same mode as would have

resulted if the same CLKMD1–3 input bits had been provided to the option-1 or option-2

hardware-programmable PLL (see Table 4), according to whether the ’545A or ’546A is an option-1 or option-2

device. Once the bootloader program has finished executing, and control is transferred to the user’s program,

the PLL can be reprogrammed to any desired configuration.

TMS320VC549 Datasheet(PDF) 38 Page - Texas Instruments