Pin Descriptions
15-4
ADSP-2126x SHARC Processor Hardware Reference
If the system clock to the
SPICLK
module is shut off in the
PMCTL
register,
FLG0–3
are not usable.
Input Synchronization Delay
The processor has several asynchronous inputs—
RESET
,
TRST
,
IRQ2–0
, DAI
pins and
FLG15-0
(when configured as inputs). These inputs can be
asserted in arbitrary phase to the processor clock,
CLKIN
. The processor
synchronizes the inputs prior to recognizing them. The delay associated
with recognition is called the synchronization delay.
Any asynchronous input must be valid prior to the recognition point in a
particular cycle. If an input does not meet the setup time on a given cycle,
it may be recognized in the current cycle or during the next cycle.
To ensure recognition of an asynchronous input, it must be asserted for at
least one full processor cycle plus setup and hold time, except for
RESET
,
which must be asserted for at least four processor cycles. The minimum
time prior to recognition (the setup and hold time) is specified in the data
sheet.
Clock Derivation
The processor uses a PLL on the chip, to provide clocks that switch at
higher frequencies than the system clock (
CLKIN
). The PLL-based clocking
methodology used influences the clock frequencies and behavior for the
serial, SPI, and parallel ports, in addition to the processor core and inter-
nal memory. In each case, the processor PLL provides a non-skewed clock
to the port logic and I/O pins.
The PLL provides a clock that switches at the processor core frequency to
the serial ports. Each of the serial ports can be programmed to operate at
clock frequencies derived from this clock. The six serial ports’ transmit
and receive clocks are divided down from the processor core clock fre-
quency by setting the
DIVx
registers appropriately.
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 ...