TMS320DM641 datasheet(89/179 Pages) TI

89 / 179 page

Power Supplies

June 2003 − Revised October 2005

SPRS222E

4.3.6

Triggering, Wake-up, and Effects

The power-down modes and their wake-up methods are programmed by setting the PWRD field (bits 15−10)

of the control status register (CSR). The PWRD field of the CSR is shown in Figure 4−9 and described in

Table 4−2. When writing to the CSR, all bits of the PWRD field should be set at the same time. Logic 0 should

be used when writing to the reserved bit (bit 15) of the PWRD field. The CSR is discussed in detail in the

TMS320C6000 CPU and Instruction Set Reference Guide (literature number SPRU189).

Reserved

Enable or

Non-Enabled

Interrupt Wake

Enabled

Interrupt Wake

PD3

PD2

PD1

R/W-0

Legend: R/W−x = Read/write reset value

NOTE: The shadowed bits are not part of the power-down logic discussion and therefore are not covered here. For information on these other

bit fields in the CSR register, see the TMS320C6000 CPU and Instruction Set Reference Guide (literature number SPRU189).

Figure 4−9. PWRD Field of the CSR Register

A delay of up to nine clock cycles may occur after the instruction that sets the PWRD bits in the CSR before the

PD mode takes effect. As best practice, NOPs should be padded after the PWRD bits are set in the CSR to

account for this delay.

If PD1 mode is terminated by a non-enabled interrupt, the program execution returns to the instruction where

PD1 took effect. If PD1 mode is terminated by an enabled interrupt, the interrupt service routine will be executed

first, then the program execution returns to the instruction where PD1 took effect. In the case with an enabled

interrupt, the GIE bit in the CSR and the NMIE bit in the interrupt enable register (IER) must also be set in order

for the interrupt service routine to execute; otherwise, execution returns to the instruction where PD1 took effect

upon PD1 mode termination by an enabled interrupt.

PD2 and PD3 modes can only be aborted by device reset. Table 4−2 summarizes all the power-down modes.

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