
Data Sheet
June 2001
DSP16410B Digital Signal Processor
204
Agere Systems—Proprietary
Use pursuant to Company instructions
Agere Systems Inc.
4 Hardware Architecture
(continued)
4.20 Power Management
(continued)
If the program running in CORE0 selects the CKI pin as
the source clock before entering standby mode, that
clock is selected as the source clock immediately after
the core exits standby mode. Likewise, if the program
running in CORE0 disables the PLL before entering
standby mode, the PLL is disabled immediately after
the core exits standby mode. Assuming the PLL is the
source clock for normal operation, the CORE0 program
must re-enable and then re-select the PLL after exiting
standby mode in order to resume full-speed process-
ing.
An interrupt causes the associated core to exit standby
mode and immediately service the interrupt. If the
interrupt is to CORE0 and the interrupt service routine
(ISR) performs time-critical processing, it must re-
enable and then reselect the PLL before performing
any processing to service the interrupt. If the interrupt
is to CORE1 and the ISR performs time-critical pro-
cessing, CORE1 must interrupt CORE0 to re-enable
and then reselect the PLL before CORE1 performs any
processing to service the interrupt. The programmer is
responsible for developing a protocol between CORE0
and CORE1 to coordinate changing clocks. Intercore
coordination is not part of the DSP16410B hardware.
If the program selects the CKI pin as the source clock
before entering standby mode, the peripherals also
operate at the slower rate. This can result in an
increased delay for a peripheral to interrupt the core to
exit standby mode.
If CORE0 or CORE1 is entering low-power standby
mode, it can save additional power by powering down
one or both of its timers (set
timer
0,1
c
[6]) prior to
entering low-power standby mode.
Section 4.10 on
page 52
describes the procedures for powering down
the timers.