Pre-Production
WM8940
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R18
0
15
14
NF1_UP
Notch filter 1 update. The notch filter 1
values used internally only update when
one of the NFU bits is set high.
Notch Filter 1 enable.
Notch Filter 1A
0
NF1_EN
0=Disabled
1=Enabled
0
0
13:0
15
NF1_A0
NF1_UP
Notch Filter 1 a0 coefficient
Notch filter 1 update. The notch filter 1
values used internally only update when
one of the NFU bits is set high.
Notch Filter 1 a1 coefficient
R19
Notch Filter 1B
0
13:0
NF1_A1
Table 16 Notch Filter 1 Function
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R20
0
15
14
NF2_UP
Notch filter 2 update. The notch filter 2
values used internally only update when
one of the NFU bits is set high.
Notch Filter 2 enable.
Notch Filter 2A
0
NF2_EN
0=Disabled
1=Enabled
0
0
13:0
15
NF2_A0
NF2_UP
Notch Filter 2 a0 coefficient
Notch filter 2 update. The notch filter 2
values used internally only update when
one of the NFU bits is set high.
Notch Filter 2 a1 coefficient
R21
Notch Filter 2B
0
13:0
NF2_A1
Table 17 Notch Filter 2 Function
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R22
0
15
14
NF3_UP
Notch filter 3 update. The notch filter 3
values used internally only update when
one of the NFU bits is set high.
Notch Filter 3 enable.
Notch Filter 3A
0
NF3_EN
0=Disabled
1=Enabled
0
0
13:0
15
NF3_A0
NF3_UP
Notch Filter 3 a0 coefficient
Notch filter 3 update. The notch filter 3
values used internally only update when
one of the NFU bits is set high.
Notch Filter 3 mode select
0 = Notch Filter mode
R23
Notch Filter 3B
0
0
14
NF3_LP
1 = Low Pass Filter mode
Notch Filter 3 a1 coefficient
13:0
NF3_A1
Table 18 Notch Filter 3 Function
The notch filter coefficients must be entered using a sign / magnitude notation. The MSB of the 14-
bit register word (NFx_Ax[13]) is reserved for the sign part, leaving the 13 remaining bits for the
magnitude part.
The notch filter coefficients are calculated as follows:
Pre-Production, Rev 3.0, February 2007
25
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
