ACTIVE
INACTIVE
All modules IDLE/STANDBY
All domain clocks gated
Sleep condition
IDLE_TRANSITION
Domain sleep conditions not satisfied
A wake-up request is received
prcm-003
CLK1
Module 1
Module 2
ICLK1
FCLK2
PRCM
Module 2
CM_b
CM_a
prcm-002
Power, Reset, and Clock Management
Figure 8-2. Generic Clock Domain
Figure above is an example of two clock managers: CM_a and CM_b. Each clock manager manages a
clock domain. The clock domain of CM_b is composed of two clocks: a functional clock (FCLK2) and an
interface clock (ICLK1), while the clock domain of CM_a consists of a clock (CLK1) that is used by the
module as a functional and interface clock. The clocks to Module 2 can be gated independently of the
clock to Module 1, thus ensuring power savings when Module 2 is not in use. The PRCM module lets
software check the status of the clock domain functional clocks. The CM_<Clock domain>_CLKSTCTRL[x]
CLKACTIVITY_<FCLK/Clock name_FCLK> bit in the PRCM module identifies the state of the functional
clock(s) within the clock domain. Table shows the possible states of the functional clock.
Table 8-7. Clock Domain Functional Clock States
CLKACTIVITY BIT Value
Status
Description
The functional clock of the clock domain is
0x0
Gated
inactive
The functional clock of the clock domain is
0x1
Active
running
8.1.3.3.1 Clock Domain-Level Clock Management
The domain clock manager can automatically (that is, based on hardware conditions) and jointly manage
the interface clocks within the clock domain. The functional clocks within the clock domain are managed
through software settings. A clock domain can switch between three possible states: ACTIVE,
IDLE_TRANSITION, and INACTIVE.
shows the sleep and wake-up transitions of the clock
domain between ACTIVE and INACTIVE states.
Figure 8-3. Clock Domain State Transitions
505
SPRUH73H – October 2011 – Revised April 2013
Power, Reset, and Clock Management (PRCM)
Copyright © 2011–2013, Texas Instruments Incorporated