Transition From Big Sleep Mode To Awake Mode; Transitions From Awake Mode; Transition From Awake Mode To Deep Sleep Mode - Texas Instruments OMAP5912 Reference Manual

Ultralow-Power Device
1.12.2

Transition From Big Sleep Mode to Awake Mode

1.13

Transitions From Awake Mode

1.13.1

Transition From Awake Mode to Deep Sleep Mode

32 Power Management
The transition to awake mode occurs when OMAP3.2 requests wake-up or
UART2 requests system clock. An OMAP3.2 wake-up request is initiated by
the unmasked interrupts of the peripherals.
The transition follows this sequence:
1) Wake-up event occurs (OMAP3.2 wake-up request or UART2 requests
system clock)
2) FSM1 enters the awake mode.
3) OMAP3.2 input clock in enabled. In external mode, the clock is effectively
restarted whenever the external system input clock arrives.
Three necessary conditions lead to deep sleep mode:
-
OMAP3.2 asserts the CHIP_IDLE signal when no clocks are needed in
OMAP3.2 or by any peripheral using OMAP3.2 output clocks.
example, DMA_LCD_CTRL.lcd_destination_port = 1 is a condition that
prevents the OMAP3.2 chip_idle to be asserted because the clock request
corresponding to the external LCD controller clock is kept active.
-
No clock request or software request by peripherals
-
POWER_CTRL_REG [4] =1
The transition follows this sequence:
1) All clock requests are inactive, CHIP_IDLE is asserted high and
POWER_CTRL_REG[4]=1. Any incoming interrupt is ignored.
2) The ULPD asserts CHIP_WAKEUP to 0. This is a sleep acknowledge, and
OMAP3.2 expects its input clock to be cut off. Interrupts can then be taken
again.
3) Input clock to peripherals is globally disabled.
4) LOW_PWR is asserted low and in oscillator mode the oscillator is also
disabled, unless POWER_CTRL_REG[9]=0.
5) FSM1 enters the deep sleep mode.
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SPRU753A