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STA306

Writing a single coefficient to RAM

– write 8-bit address to I2C register 1Ch

– write top 8-bits of coefficient in I2C address 1Dh

– write middle 8-bits of coefficient in I2C address 1Eh

– write bottom 8-bits of coefficient in I2C address 1Fh

– write 1 to W1 bit in I2C address 2Bh

Writing a set of coefficients to RAM

– write 8-bit starting address to I2C register 1Ch

– write top 8-bits of coefficient b2 in I2C address 1Dh

– write middle 8-bits of coefficient b2 in I2C address 1Eh

– write bottom 8-bits of coefficient b2 in I2C address 1Fh

– write top 8-bits of coefficient b0 in I2C address 20h

– write middle 8-bits of coefficient b0 in I2C address 21h

– write bottom 8-bits of coefficient b0 in I2C address 22h

– write top 8-bits of coefficient a2 in I2C address 23h

– write middle 8-bits of coefficient a2 in I2C address 24h

– write bottom 8-bits of coefficient a2 in I2C address 25h

– write top 8-bits of coefficient a1 in I2C address 26h

– write middle 8-bits of coefficient a1 in I2C address 27h

– write bottom 8-bits of coefficient a1 in I2C address 28h

– write top 8-bits of coefficient b1 in I2C address 29h

– write middle 8-bits of coefficient b1 in I2C address 2Ah

– write bottom 8-bits of coefficient b1 in I2C address 2Bh

– write 1 to WA bit in I2C address 2Ch

The mechanism for writing a set of coefficients to RAM provides a method of updating the five coefficients cor-

responding to a given biquad (filter) simultaneously to avoid possible unpleasant acoustic side effects. When

using this technique, the 8-bit address would specify the address of the biquad b2 coefficient (e.g. 0, 5, 10, 15,

…, 50, … 195 decimal), and the STA306 will generate the RAM addresses as offsets from this base value to

write the complete set of coefficient data.

Equalization:

Figure 3. Data Flow for single channel Biquad / Bass / Treble block.:

Five user-programmable 28-bit biquads are available per channel in the STA306. These biquads run at 192kHz

for 48kHz, 96kHz, or 192kHz input and at 176.4kHz for 44.1kHz, 88.2kHz, and 176.4kHz input. The PreScale

block is used for attenuation when filters are to be designed that boost frequencies above 0dBFS. This is a

PreScale

Biquad1

Biquad2

Biquad3

Biquad4

Biquad5

Bass/

Treble

From

1st Interpolation

Stage

To

Volume/

Limiter