Operating Modes
14-18
ADSP-214xx SHARC Processor Hardware Reference
Set the clock divisor and source and low-phase word first, followed by the
control register enable bits, which must be set together. When the
PCG_PW
register is set to zero (default) the FS pulse width is (divisor ÷ 2) for even
divisors and (divisor – 1) ÷ 2 for odd divisors. Alternatively, the
PCG_PW
register could be set high for exactly one-half the period of
CLKIN
cycles for
a 50% duty cycle, provided the FS divisor is an even number.
Clock Configuration Examples
For a
CLKIN
= 33.330 MHz the two PCGs provide the three synchronous
clocks
PCGx_CLK
,
SCLK
and
FS
for the SRCs and external DAC. These divi-
sors are stored in 20-bit fields in the
PCG_CTL
registers.
The integer divisors for several possible sample rates based on 33.330
MHz
CLKIN
are shown in
Table 14-4. Precision Clock Generator Division Ratios
(33.330 CLKIN)
Sample Rate kHz)
PCG Divisors
CLKDIV B
CLKDIV A
FSDIV A
1
1 The frame sync divisor should be an even integer in order to produce a 50% duty cycle
waveform. See
.
130.195
1
4
256
65.098
2
8
512
43.398
3
12
768
32.549
4
16
1024
26.039
5
20
1280
21.699
6
24
1536
18.599
7
28
1792
www.BDTIC.com/ADI
Содержание SHARC ADSP-214 Series
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Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...