REV. 0
AD1953
–24–
Table VI. Parameter RAM Contents (continued)
Default Value
in Fractional
Address
Function
2.20 Format
72
IIR0 Xover Left b2
0
73
IIR0 Xover Left a1
0
74
IIR0 Xover Left a2
0
75
IIR1 Xover Left b0
1.0
76
IIR1 Xover Left b1
0
77
IIR1 Xover Left b2
0
78
IIR1 Xover Left a1
0
79
IIR1 Xover Left a2
0
80
IIR0 Xover Right b0
1.0
81
IIR0 Xover Right b1
0
82
IIR0 Xover Right b2
0
83
IIR0 Xover Right a1
0
84
IIR0 Xover Right a2
0
85
IIR1 Xover Right b0
1.0
86
IIR1 Xover Right b1
0
87
IIR1 Xover Right b2
0
88
IIR1 Xover Right a1
0
89
IIR1 Xover Right a2
0
90
IIR0 Xover Sub b0
1.0
91
IIR0 Xover Sub b1
0
92
IIR0 Xover Sub b2
0
93
IIR0 Xover Sub a1
0
94
IIR0 Xover Sub a2
0
95
IIR1 Xover Sub b0
1.0
96
IIR1 Xover Sub b1
0
97
IIR1 Xover Sub b2
0
98
IIR1 Xover Sub a1
0
99
IIR1 Xover Sub a2
0
100
IIR2 Xover Sub b0
1.0
101
IIR2 Xover Sub b1
0
102
IIR2 Xover Sub b2
0
103
IIR2 Xover Sub a1
0
104
IIR2 Xover Sub a2
0
105
IIR Sub rms b0
1.0
106
IIR Sub rms b1
0
107
IIR Sub rms b2
0
108
IIR Sub rms a1
0
109
IIR Sub rms a2
0
Table VI. Parameter RAM Contents (continued)
Default Value
in Fractional
Address
Function
2.20 Format
110–142
Main Compressor
1.0 (all)
Look-Up Table Base
143
Main Compressor
5.75
10
–4
Attack/rms Time
(120 dB/sec)
Constant
144
Main Post-Compressor
1.0
Gain
145–177
Subwoofer Compressor
1.0 (all)
Look-Up Table Base
178
Sub Compressor
5.75
10
–4
Attack/RMS Time
(120 dB/sec)
Constant
179
Post-Compressor
1.0
Gain (SUB)
180
High-Pass Filter
3.92
10
–4
Cutoff Frequency
181
Main Compressor
0
Look-Ahead Delay
182
Delay Left
0
183
Delay Right
0
184
Delay Sub
0
185
Stereo Spreading
0
Coefficient
186
Stereo Spreading
0.112694
Frequency Control
187
Subwoofer Reinjection
0.0
to Main Left
188
Subwoofer Reinjection
0.0
to Main Right
189
Subwoofer Channel
0.5
Input Gain from Left IN
190
Subwoofer Channel
0.5
Input Gain from Right IN
191
Main Detector Hold Time, 0
1
Samples (4095 MAX)
192
Sub Detector Hold Time,
0
1
Samples (4095 MAX)
193
Main Detector Decay Time 0x3FFFFF
(4.597
10
6 dB/sec)1, 2
194
Sub Detector Decay Time
0x3FFFFF
(4.597
10
6 dB/sec)1, 2
NOTES
1The detector hold and decay times are integer values, while the rest of the parameters are fractional twos complement values.
2The default decay time of the hold/release circuit is set fast enough that the decay is dominated by the time constant of the rms detector.
Options for Parameter Updates
The parameter and program RAMs can be written and read
using one of several methods.
1. Direct Read/Write. This method allows direct access to the
RAMs. Since the RAMs are also being used during real-time
DSP operation, a glitch will likely occur at the output. This
method is not recommended.
2. Direct Read/Write after Core Shutdown. This method avoids
the glitch while accessing the internal RAMs by first shutting
down the core. This is recommended for transferring large
amounts of data, such as initializing the parameter RAM at
power-up or downloading a completely new program. These
transfers can be sped up by using burst mode, where an
initial address followed by blocks of data are sent to the RAM.
3. Safeload Writes Up to five SPI registers are loaded with
address/data intended for the parameter RAM. The data is then
transferred to the requested address when the RAM is not busy.
This method can be used for dynamic updates while live
program material is playing through the AD1953. For example,
a complete update of one biquad section can occur in one
audio frame while the RAM is not busy. This method is not
available for writing to the program RAM or control registers.
The next section discusses these options in more detail.