Data Sheet
July 2000
DSP16210 Digital Signal Processor
Lucent Technologies Inc.
DRAFT COPY
65
Hardware Architecture
(continued)
Power Management
(continued)
Low-Power Standby Mode, PLL Enabled and Selected.
The PLL is enabled and selected to run at 100 MHz,
assuming a constant CKI input clock of 10 MHz. Prior to entering low-power standby mode
1
by setting the AWAIT
bit (
alf
[15]), the program reduces power by turning off all the peripherals and holding the CKO pin low. The PLL
remains enabled and selected during standby mode and continues to dissipate power.
di
pllc=0xa9f2
/* Globally disable interrupts for PLL lock.
/* pllc[15]=1 enables the PLL to run at 100 MHz
/* with CKI=10 MHz. CKI must remain running.
/* Assure time for PLL to lock
if lock goto select_pll
goto pll_buzz
*/
*/
*/
*/
pll_buzz:
select_pll:
pllc=0xe9f2
ei
/* pllc[14]=1 selects the PLL.
/* Globally re-enable interrupts.
*/
*/
.
.
.
/* user code with CLK = 100 MHz
*/
powerc=0x181f
2*nop
ioc=0x0040
alf=0x8000
nop
nop
nop
...
powerc=0x0000
2*nop
ioc=0x0000
/* Prepare for standby - turn off peripherals.
/* Wait for it to take effect.
/* Hold CKO low.
/* Set AWAIT bit (stop core clock; interrupt logic
/* active.) nops needed for bedtime execution.
/* Reduced standby power plus PLL power consumed.
/* Interrupt wakes up the core.
/* User code executes here.
/* Turn peripheral units back on.
/* Wait for it to take effect.
/* CKO is free-running.
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
*/
_standby:
cont:
1. The program exits low-power standby mode when any enabled interrupt occurs. Therefore, it is assumed that interrupts are globally enabled
and at least one interrupt is individually enabled.