Clocking
8-2
ADSP-BF535 Blackfin Processor Hardware Reference
All synchronous peripherals derive their timing from
SCLK
. For example,
the Universal Asynchronous Receiver/Transmitter (UART) clock rate is
determined by further dividing the
SCLK
signal. Several of the
ADSP-BF535 peripherals, such as Universal Serial Bus (USB), Peripheral
Control Interface (PCI), and Real-Time Clock (RTC), have their own
clock inputs that operate asynchronously to
SCLK
.
Phase Locked Loop and Clock Control
To provide the clock generation for the core and system, the
ADSP-BF535 processor uses an analog PLL with programmable state
machine control.
The PLL design serves a wide range of applications. It emphasizes embed-
ded and portable applications in which performance, flexibility and
control of power dissipation are key features. This broad range of applica-
tions requires a wide range of frequencies for the clock generation
circuitry. The PLL interacts with the Dynamic Power Management Con-
troller (DPMC) block to provide power management functions for the
ADSP-BF535 processor.
PLL Overview
The PLL supports a wide range of multiplier ratios, achieving 1–31x mul-
tiplication of the input clock,
CLKIN
. To achieve this wide multiplication
range, the ADSP-BF535 processor uses a combination of programmable
dividers in the PLL feedback circuit and output configuration blocks.
Figure 8-1
illustrates a conceptual model of the PLL circuitry, configura-
tion inputs, and resulting outputs.
The input clock,
CLKIN
, is a square wave derived from a crystal oscillator
or external reference clock. The Voltage Controlled Oscillator (
VCO
) is an
intermediate clock from which the core clock (
CCLK
) and system clock
(
SCLK
) are derived.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...