GC4116 Datasheet, PDF (45/57 Pages) List of Unclassifed Manufacturers – MULTI-STANDARD QUAD DUC CHIP

GC4116 MULTI-STANDARD QUAD DUC CHIP
DATA SHEET REV 1.0
RESAMPLER CONTROL PAGE 8 (continue)
ADDRESS 23: Ratio Map Register Suggested default = 0x00
BIT
0-1 LSB
2-3
4-5
6-7 MSB
TYPE
R/W
R/W
R/W
R/W
NAME
RATIO_MAP_0
RATIO_MAP_1
RATIO_MAP_2
RATIO_MAP_3
DESCRIPTION
The ratio map for resampler channel 0. This tells the hardware which resampler
ratio should be use for resampler channel 0.
The ratio map for resampler channel 1.
The ratio map for resampler channel 2.
The ratio map for resampler channel 3.
The default ratio maps select ratio 0 for all four channels. The resampler in the GC4116 must use the same ratio for all
resampler channels, which means that the valid values for the ratio map are 0x00, 0x55, 0xAA and 0xFF to select ratio 0, 1, 2 or 3.
The ratio maps can also be used to synchronously switch between resampling ratios. This allows the chip’s resampler to be
used in timing loops where the ratio must toggle between several values which have been programmed into the chip.
5.9 RESAMPLER RATIO PAGE (PAGE 9)
This page stores four resampler ratios to be used by the resampler channels. Each ratio is the 32 bit ratio of the input sample
rate to the output sample rate with an implicit decimal point six bits down from the top. The total range for the ratio is then 0 to
63. The hardware limits the decimation to be less than 32 (hence the MSB of the 32 bit word should always be zero).
RATIO = 2²⁶(Input Sample Rate)/(Output Sample Rate)
Table 9: Resampler Ratio Page
ADDRESS
16
17
18
19
20
21
22
23
NAME
RATIO_0 (LSBs)
RATIO_0
RATIO_0
RATIO_0 (MSBs)
RATIO_1 (LSBs)
RATIO_1
RATIO_1
RATIO_1 (MSBs)
ADDRESS
24
25
26
27
28
29
30
31
NAME
RATIO_2 (LSBs)
RATIO_2
RATIO_2
RATIO_2 (MSBs)
RATIO_3 (LSBs)
RATIO_3
RATIO_3
RATIO_3 (MSBs)
The ratio map register selects which ratio is used by the resampler.
© 1999−2001 GRAYCHIP,INC.
- 40 -
APRIL 27, 2001
This document contains preliminary information which may be changed at any time without notice