STA335BWS datasheet(55/68 Pages) STMICROELECTRONICS

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STA335BWS

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6.12.17

Coefficient write/read control register

Coefficients for user-defined EQ, Mixing, Scaling, and Bass Management are handled

internally in the STA335BWS via RAM. Access to this RAM is available to the user via an

I2C register interface. A collection of I2C registers are dedicated to this function. One

contains a coefficient base address, five sets of three store the values of the 24-bit

coefficients to be written or that were read, and one contains bits used to control the

write/read of the coefficient(s) to/from RAM.

Three different RAM banks are embedded in STA335BWS. The 3 banks are managed in

paging mode using EQCFG register bits. They can be used to store different EQ settings.

For speaker frequency compensation, a sampling frequency independent EQ must be

implemented. Computing 3 different coefficients set for 32 kHz, 44.1kHz, 48 kHz and

downloading them in the 3 RAM banks, it is possible to select the suitable RAM block

depending from the incoming frequency with a simple I2C write operation on register 0x31.

For example, in case of different input sources (different sampling rates), the 3 different set

of coefficients can be downloaded once at the start up, and during the normal play it is

possible to switch among the 3 RAM blocks allowing a faster operation, without any

additional download from the microcontroller.

To write the coefficients in a particular RAM bank, this bank must be selected first writing bit

0 and bit 1 in register 0x31. Then the below write procedure can be used.

Note that as soon as a RAM bank is selected, the EQ settings will be automatically switched

to the coefficients stored in the active RAM block.

Note:

The read and write operation on RAM coefficients works only if LRCKI (pin 29) is switching.

Reading a coefficient from RAM

Select the RAM block with register 0x31 bit1, bit0.

Write 6-bits of address to I2C register 0x16.

Write 1 to R1 bit in I2C address 0x26.

Read top 8-bits of coefficient in I2C address 0x17.

Read middle 8-bits of coefficient in I2C address 0x18.

Read bottom 8-bits of coefficient in I2C address 0x19.

Reading a set of coefficients from RAM

Select the RAM block with register 0x31 bit1, bit0.

Write 6-bits of address to I2C register 0x16.

Write 1 to RA bit in I2C address 0x26.

Read top 8-bits of coefficient in I2C address 0x17.

Read middle 8-bits of coefficient in I2C address 0x18.

Read bottom 8-bits of coefficient in I2C address 0x19.

Read top 8-bits of coefficient b2 in I2C address 0x1A.

Read middle 8-bits of coefficient b2 in I2C address 0x1B.

Reserved

STA335BWS Datasheet(PDF) 55 Page - STMicroelectronics

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