TNETV2501INPGF datasheet(77/197 Pages) TI1

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Functional Overview

December 2002 − Revised November 2008

SPRS206K

3.10 Idle Control

The Idle function is implemented for low power consumption. The Idle function achieves low power

consumption by gating the clock to unused parts of the chip, and/or setting the clock generator (PLL) and the

internal oscillator to a power-down mode.

3.10.1

Clock Domains

The 5501 provides six clock domains to power-off the main clock to the portions of the device that are not being

used. The six domains are:

•

CPU Domain

•

Master Port Domain (includes DMA and HPI modules)

•

ICACHE

•

Peripherals Domain

•

Clock Generator Domain

•

EMIF Domain

3.10.2

IDLE Procedures

Before entering idle mode (executing the IDLE instruction), the user has first to determine which part of the

system needs to be disabled and then program the Idle Control Register (ICR) accordingly. When the IDLE

instruction is executed, the ICR will be copied into the Idle Status Register (ISTR). The different bits of the ISTR

ICR as some IDLE domain combinations are not valid (for example: CPU on and clock generator off).

3.10.2.1 CPU Domain Idle Procedure

The 5501 CPU can be idled by executing the following procedure.

Write ‘1’ to the CPUI bit (bit 0 of ICR).

Execute the IDLE instruction.

CPU will go to idle state

3.10.2.2 Master Port Domain (DMA/HPI) Idle Procedure

The clock to the DMA module and/or the HPI module will be stopped when the DMA and/or the HPI bit in the

MICR is set to 1 and the MPIS bit in the ISTR becomes 1. The DMA will go into idle immediately if there is no

data transfer taking place. If there is a data transfer taking place, then it will finish the current transfer and then

go into idle. The HPI will go into idle regardless of whether or not there is a data transfer taking place. Software

must confirm that the HPI has no activity before setting it to idle.

The 5501 DMA module and the HPI module can be disabled by executing the following procedure.

Write ‘1’ to the DMA bit and/or the HPI bit in MICR.

Write ‘1’ to the MPI bit in ICR.

Execute the IDLE instruction.

DMA and/or HPI go/goes to idle.

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