Power Management
15-24
15.3.1 DSP Idle Modes
Two DSP registers are used to configure and check the idle modes for the DSP
subdomains.
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The idle configuration register (ICR) specifies which clock domains get put
into IDLE by the next execution of the IDLE instruction.
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The idle status register (ISR) indicates which subdomains are currently in
IDLE mode.
The six different subdomains are:
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DSP core subdomain (DSP CORE/SARAM/DARAM): ICR and ISR bit 0
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DSP DMA controller subdomain (DMA/SARAM/DARAM): ICR and ISR bit 1
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I-cache subdomain (I-cache): ICR and ISR bit 2
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Peripherals subdomain (peripherals outside the DSP): ICR and ISR bit 3:
Peripherals can be individually controlled (shut off/enabled) by program-
ming the control registers in the clock generation management module
(CLKM). To maximize power conservation, seven different peripheral idle
modes are defined (UART, GPIO, timers, watchdog timer). Each one can
be individually activated and deactivated by software.
Two different strategies are used to control the clock that feeds the DSP
peripherals:
J
The clock is shut off/activated according to the DSP idle mode or ap-
plication-specific environment (disable the peripheral clocks when the
DSP in not in idle). Peripherals connected to this clock cannot request
DMA transfers during the DSP idle mode.
J
The clock is never shut off (input reference clock).
In either case, the DSP peripheral clocks are directly shut off/activated
by the DSP software.
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DPLL subdomain (DSP input clock + DSP interrupt handler): ICR and ISR
bit 4
Setting up the DSP DPLL idle mode sends a DSP_IDLE signal to the clock
generation management module (CLKM), which disables the input clock
to the DSP.
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DSP EMIF subdomain: ICR and ISR bit 5