
ADSP-2126x SHARC Processor Hardware Reference
13-7
Precision Clock Generator
respectively, these outputs are activated when a low to high transition is
sensed in the external clock (
MISCA4_I
,
MISCA5_I
).
Phase Shift
Another PCG frame sync parameter provides for phase shifting with
respect to the clock of the same unit. This feature allows shifting in time
relative to clock signals. Frame sync phase shifting is often required by
peripherals that need to lead or lag a clock signal. For example, the I
2
S
protocol specifies that the frame sync should transition from high to low
one clock cycle before the beginning of a frame. Since an I
2
S frame is 64
clock cycles long, delaying the frame sync by 63 cycles produces the
required framing.
The amount of phase shifting is specified as a 20-bit value in the
FSA-
PHASE_HI
bit field (bits 29–20) of the
PCG_CTLA_O
register and in the
FSAPHASE_LO
bit field (bits 29–20) of the
PCG_CTLA_1
register for unit A.
A single 20-bit value spans these two bit fields. The upper half of the word
[19:10] is in the
PCG_CTLA_O
register, and the lower half [9:0] is in the
PCG_CTLA_1
register.
Similarly, the phase shift for frame sync B is specified in the
PCG_CTLB_O
and
PCG_CTLB_1
registers.
When using a clock and frame sync as a synchronous pair, the units
must be enabled in a single atomic instruction before their parame-
ters are modified. Both units must also be disabled in a single
atomic instruction.
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...