STA335BWS View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
STA335BWS Datasheet PDF : 68 Pages
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STA335BWS
Register description
6.12.17 Coefficient write/read control register
Note:
D7
D6
D5
D4
D3
D2
D1
D0
Reserved
RA
R1
WA
W1
0
0
0
0
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.
The read and write operation on RAM coefficients works only if LRCKI (pin 29) is switching.
Reading a coefficient from RAM
1. Select the RAM block with register 0x31 bit1, bit0.
2. Write 6-bits of address to I2C register 0x16.
3. Write 1 to R1 bit in I2C address 0x26.
4. Read top 8-bits of coefficient in I2C address 0x17.
5. Read middle 8-bits of coefficient in I2C address 0x18.
6. Read bottom 8-bits of coefficient in I2C address 0x19.
Reading a set of coefficients from RAM
1. Select the RAM block with register 0x31 bit1, bit0.
2. Write 6-bits of address to I2C register 0x16.
3. Write 1 to RA bit in I2C address 0x26.
4. Read top 8-bits of coefficient in I2C address 0x17.
5. Read middle 8-bits of coefficient in I2C address 0x18.
6. Read bottom 8-bits of coefficient in I2C address 0x19.
7. Read top 8-bits of coefficient b2 in I2C address 0x1A.
8. Read middle 8-bits of coefficient b2 in I2C address 0x1B.
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