Pentek 6230 Operating Manual page 157

GC4016 MULTI-STANDARD QUAD DDC CHIP
ADDRESS 19: Final Shift Register, Suggested default = 0x34
BIT TYPE
0-3 LSB R/W
4-5 R/W
6 R/W
7 (MSB R/W
ADDRESS 20: Channel Map Register, Suggested default = 0xE4
BIT TYPE
0-1 LSB R/W
2-3 R/W
4-5 R/W
6-7 MSB R/W
This register maps down converter channels to output (resampler) channels. For most applications this will be a simple map
of channel A to output channel 0, channel B to output channel 1, etc. However, for multichannel modes (see Section 3.4) such
as SPLITIQ two or even four channels may be directed to the same output channel.
ADDRESS 21: Add-To Register, Suggested default = 0x70
BIT TYPE
0 LSB R/W
1 R/W
2 R/W
3 R/W
4-6 R/W
7 MSB R/W
When processing complex input signals partial results are computed in adjacent channels that must be summed together to
produce a meaningful result. This control bit informs the resampler to save the data presented to it's input and add it to the next
sample presented (if the chip is properly set up this will be from the next channel). In this manner the real and imaginary portions
of the input are rejoined prior to resampling.
ADDRESS 22: Resampler Clock Divide Register, Suggested default = 0x00
BIT TYPE
0-7 R/W
In many applications only a small portion of the resampler computational throughput is required. Power can be reduced by
dividing the clock driving the resampler. The resampler clock rate is 2*F
© GRAYCHIP,INC.
This document contains information which may be changed at any time without notice
NAME DESCRIPTION
FINAL_SHIFT The final shift up applied to all output channels before rounding and outputting.
Legal values are 0-15.
ROUND Round the output to 12 (ROUND=0), 16 (ROUND=1), 20 bits (ROUND=2) or 24
bits (ROUND=3). Note, the data is output from the resampler in all cases as 24
bit words. Rounding is into the MSBs, unused LSBs of the 24 bit output words
are not cleared. The chip's output word size is set by BITS_PER_WORD in the
output page, not by ROUND.
TAG_22 Two bit tag mode. Replaces the 2 LSBs of the 24 bit resampler output word with
the 2 LSBs of the tag words. Changes the 24 bit round mode (ROUND=3), if it is
used, to be a 22 bit round mode.
Unused
NAME DESCRIPTION
CHAN_MAP_A The channel map for channel A. This tells the hardware which output channel
the results of down converter channel A should be directed to.
CHAN_MAP_B The channel map for down converter channel B.
CHAN_MAP_C The channel map for down converter channel C.
CHAN_MAP_D The channel map for down converter channel D.
NAME DESCRIPTION
ADD_A_TO_B Add down converter channel A to down converter channel B.
ADD_B_TO_C Add down converter channel B to down converter channel C.
ADD_C_TO_D Add down converter channel C to down converter channel D.
ADD_D_TO_NEXT_A Not useful. Must be set to zero.
RATIO_SYNC Changes to the ratio map (address 23) are synchronized to this sync source.
Unused
NAME DESCRIPTION
RES_CLK_DIV Resampler clock division.
/(1+RES_CLK_DIV). Caution must be used to avoid
CK
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DATA SHEET REV 1.0
August 27, 2001