Ulpd Mode Descriptions; Ulpd Mechanisms Description - Texas Instruments OMAP5912 Reference Manual

Power Management User Services
3.4.2

ULPD Mode Descriptions

3.4.3

ULPD Mechanisms Description

86 Power Management
The following describes the three system power modes:
-
In deep sleep (lowest-consumption mode):
J
Only Clk32k clock, used by the ULPD and RTC modules, is on.
J
The system clock is off.
-
In big sleep (low-consumption mode):
J
Clk32k and the system clocks, used by ULPD, RTC modules, and
external peripherals, are on.
J
The OMAP5912 clock reference is off.
-
In awake mode:
J
Clk32k and system clocks are on.
J
OMAP5912 clock reference provide by ULPD is on.
From a consumption point of view, it is best to go into idle mode (standby MPU
signal activated) whenever possible.
To handle power mode transition, the ULPD module controls principally:
-
Standby wait for interruption signal received from the ARM926EJS
processor.This signal is generated from specific MPU instruction
decoding (software running).
-
Idle request signals sent to all OMAP5912 clock domains
-
Idle acknowledge signals from all OMAP5912 clock domains
-
Wake-up signal (from external or internal requests)
The different clock requests to the ULPD are described in Table 4.
Software is responsible for requesting the transition from the awake mode to
the deep sleep or big sleep modes.
All OMAP clock domains determine whether to validate transitions (with
acknowledge signals) to the next state according to their activity.
The main steps in the transition from the awake mode to other modes are
shown in Figure 24.
SPRU753A