GC1115 Datasheet, PDF (56/80 Pages) Texas Instruments – Crest Factor Reduction Processor

GC1115
SLWS144 – FEBRUARY 2005
www.ti.com
SNAP_A_MAXVAL 0x65 (101) Type: Read/Write Value at RESET: 0x0000
The SNAP_A_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_A_MINVAL, while the maximum value of interest is SNAP_A_MAXVAL. Input values ≤
SNAP_A_MINVAL will be counted in Snapshot RAM A’s histogram bin 0. Input values ≥ SNAP_A_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_A_SCALE
0x66 (102) Type: Read/Write
Value at RESET: 0x0000
The SNAP_A_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_A_MINVAL and
SNAP_A_MAXVAL. However, the difference between SNAP_A_MAXVAL and SNAP_A_MINVAL can be larger
than the number of histogram bins (1024). SNAP_A_SCALE is used to scale the difference between the input
value (to be histogrammed) and SNAP_A_MINVAL into the allowed 10-bit histogram index range (0..1023). The
GC1115 user is responsible for ensuring that SNAP_A_SCALE limits histogram indices to the range 0..1023.
SNAP_A_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_A_HISTCOUNT 0x67 (103) Type: Read/Write Value at RESET: 0x0000
The SNAP_A_HISTCOUNT register determines how many groups of samples will be observed in histogram
mode. SNAP_A_HISTCOUNT is used only during Snapshot RAM A histogram mode operation.
SNAP_A_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_A_HISTCOUNT. Thus the total number of samples observed in histogram mode is POWER_CNT ×
SNAP_A_HISTCOUNT. At reset, POWER_CNT = 0xFFFF, or 65535.
BITS
[15:0]
DESCRIPTION
Number of POWER_CNT sample groups to be histogrammed.
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