AD1981BL Analog Devices, AD1981BL Datasheet - Page 22

• Manufacturer Part Number: AD1981BL
• Description: Low Voltage AC'97 Soundmax Codec
• Manufacturer: Analog Devices

AD1981BL
Register 60h is a read/write register that controls the equalizer functionality and data setup. This register also contains the Biquad and Coefficient Address pointer,
which is used in conjunction with the EQ Data Register (78h) to set up the equalizer coefficients. The reset default disables the equalizer function until the coefficients
can be properly set up by the software and sets the Symmetry bit to allow equal coefficients for left and right channels. All registers not shown and bits containing an X
are assumed to be reserved.
BCA[5,0]
CHS
SYM
MAD
LBEN
EQM
Reg
No. Name
60h EQ CTRL EQM
D15
Equalizer Mute. When set to 1, this bit disables the equalizer function (allows all data to pass through). The
reset default sets this bit to 1, disabling the equalizer function until the biquad coefficients can be properly set.
Biquad and Coefficient Address Pointer
biquad 0 coef a0 BCA[5,0] = 011011
biquad 0 coef a1 BCA[5,0] = 011010
biquad 0 coef a2 BCA[5,0] = 011001
biquad 0 coef b1 BCA[5,0] = 011101
biquad 0 coef b2 BCA[5,0] = 011100
biquad 1 coef a0 BCA[5,0] = 100000
biquad 1 coef a1 BCA[5,0] = 011111
biquad 1 coef a2 BCA[5,0] = 011110
biquad 1 coef b1 BCA[5,0] = 100010
biquad 1 coef b2 BCA[5,0] = 100001
biquad 2 coef a0 BCA[5,0] = 100101
biquad 2 coef a1 BCA[5,0] = 100100
biquad 2 coef a2 BCA[5,0] = 100011
biquad 2 coef b1 BCA[5,0] = 100111
biquad 2 coef b2 BCA[5,0] = 100110
biquad 3 coef a0 BCA[5,0] = 101010
biquad 3 coef a1 BCA[5,0] = 101001
biquad 3 coef a2 BCA[5,0] = 101000
biquad 3 coef b1 BCA[5,0] = 101100
biquad 3 coef b2 BCA[5,0] = 101011
biquad 4 coef a0 BCA[5,0] = 101111
biquad 4 coef a1 BCA[5,0] = 101110
biquad 4 coef a2 BCA[5,0] = 101101
biquad 4 coef b1 BCA[5,0] = 110001
biquad 4 coef b2 BCA[5,0] = 110000
biquad 5 coef a0 BCA[5,0] = 110100
biquad 5 coef a1 BCA[5,0] = 110011
biquad 5 coef a2 BCA[5,0] = 110010
biquad 5 coef b1 BCA[5,0] = 110110
biquad 5 coef b2 BCA[5,0] = 110101
biquad 6 coef a0 BCA[5,0] = 111001
biquad 6 coef a1 BCA[5,0] = 111000
biquad 6 coef a2 BCA[5,0] = 110111
biquad 6 coef b1 BCA[5,0] = 111011
biquad 6 coef b2 BCA[5,0] = 111010
Channel Select.
CHS = 0 selects left channel coefficients data block.
CHS = 1 selects right channel coefficients data block.
Symmetry. When set to 1, this bit indicates that the left and right channel coefficients are equal. This shortens
the coefficients’ setup sequence since only the left channel coefficients need to be addressed and set up (the right chan-
nel coefficients are fetched from the left channel memory).
Mixer ADC Loopback Enable. Enables mixer ADC data to be summed into PCM stream.
0 = No loopback allowed (default).
1 = Enable loopback.
D14
MAD
LBEN
D13
X
D12
X
D11
X
EQ Control Register (Index 60h)
D10
X
D9
X
–22–
D8
X
D7
SYM CHS
D6
D5
BCA5 BCA4 BCA3 BCA2 BCA1 BCA0 8080h
D4
D3
D2
D1
D0
Default
REV. 0