GC1115_06 Datasheet, PDF (60/82 Pages) Texas Instruments – Crest Factor Reduction Processor

GC1115
SLWS144C – FEBRUARY 2005 – REVISED JUNE 2006
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SNAP_B_MAXVAL 0x75 (117) Type: Read/Write
Value at RESET: 0x0000
The SNAP_B_MAXVAL register is used only during Snapshot RAM A histogram mode. In histogram mode, the
microprocessor or DSP can specify a desired range of values to be histogrammed. The minimum value of
interest is SNAP_B_MINVAL, while the maximum value of interest is SNAP_B_MAXVAL. Input values
SNAP_B_MINVAL will be counted in Snapshot RAM A’s histogram bin 0. Input values SNAP_B_MAXVAL will
be counted in Snapshot RAM A’s histogram bin 1023.
BITS
[15:0]
DESCRIPTION
Snapshot RAM A (in histogram mode): maximum allowable value
SNAP_B_SCALE
0x76 (118) Type: Read/Write
Value at RESET: 0x0000
The SNAP_B_SCALE register is used only during Snapshot RAM A histogram mode. In histogram mode, the
microprocessor or DSP can specify a desired range of values to be histogrammed, using SNAP_B_MINVAL and
SNAP_B_MAXVAL. However, the difference between SNAP_B_MAXVAL and SNAP_B_MINVAL can be larger
than the number of histogram bins (1024). SNAP_B_SCALE is used to scale the difference between the input
value (to be histogrammed) and SNAP_B_MINVAL into the allowed 10-bit histogram index range (0..1023). The
GC1115 user is responsible for ensuring that SNAP_B_SCALE limits histogram indices to the range 0..1023.
SNAP_B_SCALE is interpreted as an unsigned 14-bit fractional value, from 0x0000 = 0.0 to 0x3FFF = 1.0.
BITS
[13:0]
[15:14]
DESCRIPTION
Snapshot RAM A (in histogram mode): maximum allowable value
Reserved
Histogram index calculation:
if ( (sample[i] >= SNAP_MINVAL) && (sample[i] <= SNAP_MAXVAL) ) {
j = sample[i] - SNAP_MINVAL;
index = int(j * SNAP_SCALE);
hist[index]++
}
The GC1115 user is responsible for ensuring that index (the product of j × SNAP_SCALE) is in the allowed
range of 0..1023.
SNAP_B_HISTCOUNT 0x77 (119)
Type: Read/Write
Value at RESET: 0x0000
The SNAP_B_HISTCOUNT register determines how many groups of samples will be observed in histogram
mode. SNAP_B_HISTCOUNT is used only during Snapshot RAM A histogram mode operation.
SNAP_B_HISTCOUNT works in conjunction with POWER_CNT (0x7F). The number of samples in a group is
specified in POWER_CNT, while the number of groups monitored during histogram mode is specified in
SNAP_B_HISTCOUNT. Thus the total number of samples observed in histogram mode is POWER_CNT *
SNAP_B_HISTCOUNT. At reset, POWER_CNT = 0xFFFF, or 65535.
BITS
[15:0]
DESCRIPTION
Number of POWER_CNT sample groups to be histogrammed.
60
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