Power, Reset, and Clock Management
8.1.4.5
Wakeup Sources/Events
Following events will wake up the device from Deep sleep(low power) modes. These are part of the
Wakeup Power domain and remain always ON.
Note: For differences in operation based on AM335x silicon revision, see
, Silicon Revision
Functional Differences and Enhancements.
•
GPIO0 bank
•
dmtimer1_1ms (timer based wakeup)
•
USB2PHY (USB resume signaling from suspend) – Both USB ports supported.
•
TSC (touch screen controller, ADC monitor functions )
•
UART0 (Infra-red support)
•
I2C0
•
RTC alarm
These wake events apply on any of the deep sleep modes and standby mode.
8.1.4.6
Functional Sequencing for Power Management with Cortex M3
The AM335x device contains a dedicated Cortex M3 processor to handle the power management
transitions. It is part of the Wake up Power domain (PD_WKUP). Implementing the Power modes are part
of the MPU and Cortex A8 processors.
The power management sequence kicks off with Cortex A8 MPU executing a WFI instruction with the
following steps:
1. During Active power mode, the Cortex A8 MPU executes a WFI instruction to enter IDLE mode.
2. Cortex M3 gets an interrupts and gets active, It powers down the MPU power domain( if required).
3. Registers interrupt for the Wake up peripheral(which is listed in Wake up sources in previous section).
4. Executes WFI and goes into idle state.
5. The wake up event triggers an interrupt to Cortex M3 system and it wakes up the Cortex A8 MPU.
Generally, A8 and CortexM3 are not expected to be active at the same time CortexM3 along with PRCM
is the power manager primarily for PD_MPU and PD_PER. Other power domains (e.g., PD_GFX) may be
handled directly using Cortex A8 MPU software.
gives a system level view of the Power
management system between Cortex A8 MPU and Cortex M3.
514
Power, Reset, and Clock Management (PRCM)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated