Analog Devices SHARC ADSP-2136 Series Hardware Reference Manual page 396

Functional Description
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SRCx_FS_IP SRCx_FS_OP
put of an
SRCx_FS_OP
>
SRCx_FS_OP SRCx_FS_IP
, the sample rate ratio is updated if it is different by more than
SRCx_FS_OP
two
SRCx_FS_OP
comparison. This is done to provide some hysteresis to prevent the filter
length from oscillating and causing distortion.
However, the hysteresis of the (
cause phase mismatching between two SRCs operating with the same
input and output clocks. Since the hysteresis requires a difference of more
than two
SRCx_FS_OP
ratios, two SRCs may have differences in their ratios from 0 to 4
period counts. The (
SRCx_FS_OP
the filter length of the SRC, which corresponds directly with the group
delay. Thus, the magnitude in the phase difference depends upon the res-
olution of the
SRCx_FS_OP
resolution of the counters, the smaller the phase difference error.
Serial Data Ports
The serial data ports provide the interface through which data is trans-
ferred into and out of the SRC modules.
The SRC has a 3-wire interface for the serial input and output ports that
supports left-justified, I
modes. Additionally, the serial interfaces support TDM mode for
daisy-chaining multiple SRCs to a processor. The serial output data is
dithered down to 20, 18, or 16 bits when 20-, 18-, or 16-bit output data
is selected.
The SRC converts the data from the seri a l input port to the sample rate of
the serial output port. The sample rate at the serial input port can be asyn-
chronous with respect to the output sample rate of the output serial port.
12-8
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. The ratio is calculated by comparing the out-
counter to the output of an
, the ratio is held at one. If
periods from the previous
SRCx_FS_OP
periods to update the
SRCx_FS_OP
and
SRCx_FS_IP
2
S, and right-justified (16-, 18-, 20-, 24-bit)
ADSP-2136x SHARC Processor Hardware Reference
for the ADSP-21362/3/4/5/6 Processors
SRCx_FS_IP
SRCx_FS_IP
to
SRCx_FS_OP SRCx_FS_IP
)/( ) ratio circuit can
SRCx_FS_IP
and
SRCx_FS_OP SRCx_FS_IP
)/( ) ratio adjusts
SRCx_FS_IP
counters. The greater the
counter. If
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