
ADSP-2126x SHARC Processor Hardware Reference
15-5
System Design
On power-up, the
CLKCFG1–0
pins are used to select ratios of 16:1, 8:1,
and 3:1. After booting, numerous other ratios (slowing or speeding up the
clock) can be selected via software control using the Power Management
Control register.
Power Management Control Register
The ADSP-2126x has a Power Management Control register (
PMCTL
) that
allows programs to determine the amount of power dissipated. This
includes the ability to program the PLL dynamically in software. This fea-
ture eases design for systems that need to use specific clock frequencies or
are sensitive to power consumption.
In addition to changing the clock rate on the fly, The
PMCTL
register also
allows programs to disable the clock source to a particular processor
peripheral completely, (for example the serial ports or the timers), to fur-
ther conserve power. By default, each peripheral block has its internal
CLK
enabled only after it is initialized. Programs can use the
PMCTL
register to
turn the specific peripheral off after the application no longer needs it.
After reset these clocks are not enabled until the peripheral is initialized by
the program.
are examples that show how to use the
Power Management Control register to enable/disable clocking to a
peripheral.
Listing 15-1. Power Management Example
ustat2 = dm(PMCTL);
bit set ustat2 SPIPDN; /* disable internal peripheral clock for
SPI module. SPIPDN is defined as bit 3
of PMCTL*/
dm(PMCTL) = ustat2;
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...