ADSP-1981BL_15 Datasheet, PDF (25/32 Pages) Analog Devices – AC 97 SoundMAX Codec

Bit
CHS
SYM
MAD
LBEN
EQM
AD1981BL
Mnemonic
Channel Select
Symmetry
Mixer ADC Loopback
Enable
Equalizer Mute
Function
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
CHS = 0 selects the left-channel coefficient’s data block.
CHS = 1 selects the right-channel coefficient’s data block.
When set to 1, this bit indicates that the left- and right-channel coefficients are equal. This
shortens the coefficients’ setup sequence, because only the left-channel coefficients need to be
addressed and set up. The right-channel coefficients are fetched from the left-channel memory.
Enables mixer ADC data to be summed into the PCM stream.
0 = No loopback allowed (default).
1 = Enable loopback.
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.
Rev. A | Page 25 of 32