March 26, 2021

3.2

ES9016K2M Datasheet

21

ESS TECHNOLOGY, INC. 109 Bonaventura Drive, San Jose, CA 95134, USA Tel (408) 643-

8800 • www.esstech.com

Register #26: Programmable Filter Address

8 bit, Read-Write Register, Default = 0x00

Bits

[7]

[6:0]

Mnemonic

prog_coeff_stage

prog_coeff_addr

Default

0

0

0

0

0

0

0

0

Bit

Mnemonic

Description

[7]

prog_coeff_stage

Selects which stage of the filter to write.

1'b0 = Stage 1 of the oversampling filter (128 coefficients)

1'b1 = Stage 2 of the oversampling filter (16 coefficients)

[6:0]

prog_coeff_addr

Selects the coefficient address when writing custom coefficients

for the oversampling filter.

Register #29-27: Programmable Filter Coefficient

8 bit, Read-Write Register, Default = 0x000000

Bits

[23:0]

Mnemonic

prog_coeff

Default

24’d0

Bit

Mnemonic

Description

[23:0]

prog_coeff

A 24bit filter coefficients that will be written to address 'prog_coeff_addr'.

Register #30: Programmable Filter Control

8 bit, Read-Write Register, Default = 0x00

Bits

[7:3]

[2]

[1]

[0]

Mnemonic

reserved *

even_stage2_coeff

prog_coeff_we

prog_coeff_en

Default

0

0

0

0

0

0

0

0

Bit

Mnemonic

Description

[7:3]

reserved *

[2]

even_stage2_coeff

Sets the type of symmetry of the stage 2 programmable filter.

1'b0 = Uses a sine symmetric filter (27 coefficients).

1'b1 = Uses a cosine symmetric filter (28 coefficients).

[1]

prog_coeff_we

1'b0 = Disable writing to the custom filter coefficients.

1'b1 = Enable writing to the custom filter coefficients.

Note: When set to 1'b1 the custom filter will be bypassed

regardless of the state of register 21[0].

[0]

prog_coeff_en

1'b0 = Use one of the built-in oversampling filters.

1'b1 = Use the custom oversampling filter.

Note: The custom filter is not programmed to anything on reset,

valid coefficients must be written to the filter before enabling.

* All Reserved Bits in Register #30 must be set to the indicated logic level to ensure correct device operation.

Note: even_stage2_coeff sets the type of symmetry used by the second stage filter. The actual RAM is 16 coefficients, but

only the first 14 coefficients are used when applying the oversampling filter. The first 14 coefficients are mirrored using either

sine or cosine symmetry, resulting in a filter length of either 27 or 28 taps. This means that the second stage RAM should

only contain half of the impulse response of the second stage filter, and the impulse peak value will be contained in the 14th

coefficient. Also note that, due to the symmetry of the filter, only linear phase filters may be used in the second stage.