WM8904
Pre-Production
The “knee” in Figure 29 is represented by register fields DRC_KNEE_IP and DRC_KNEE_OP.
Parameter Y0, the output level for a 0dB input, is not specified directly, but can be calculated from the
other parameters, using the equation
The DRC Compression parameters are defined in Table 16.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R43 (2Bh)
Input signal at the Compressor
'knee'.
10:5
DRC_KNEE_IP
[5:0]
00_0000
DRC Control 3
000000 = 0dB
000001 = -0.75dB
000010 = -1.5dB
… (-0.75dB steps)
111100 = -45dB
111101 to 111111 = Reserved
Output signal at the Compressor
'knee'.
4:0
DRC_KNEE_OP
[4:0]
0_0000
00000 = 0dB
00001 = -0.75dB
00010 = -1.5dB
… (-0.75dB steps)
11110 = -22.5dB
11111 = Reserved
Compressor slope (upper region)
000 = 1 (no compression)
001 = 1/2
R42 (2Ah)
5:3
DRC_HI_COMP
[2:0]
000
DRC Control 2
010 = 1/4
011 = 1/8
100 = 1/16
101 = 0
110 to 111 = Reserved
Compressor slope (lower region)
000 = 1 (no compression)
001 = 1/2
2:0
DRC_LO_COMP
[2:0]
000
010 = 1/4
011 = 1/8
100 = 0
101 to 111 = Reserved
Table 16 DRC Compression Control
PP, Rev 3.3, September 2012
54
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