May 4, 2020

CONFIDENTIAL INFORMATION Rev. 1.2

SABRE9006A Datasheet

9

ESS TECHNOLOGY, INC. 237 South Hillview Drive, Milpitas, CA 95035, USA Tel (408) 643-

8800 • Fax (408) 643-8801

Programmable FIR filter

A two stage interpolating FIR design is used. The interpolating FIR filter is generated using MATLAB, and can then be

downloaded using a custom C code.

Example Source Code for Loading a Filter

// only accept 128 or 16 coefficients

// Note:

The coefficients must be quantized to 24 bits for this method!

// Note:

Stage 1 consists of 128 values (0-127 being the coefficients)

// Note:

Stage 2 consists of 16 values (0-13 being the coefficients, 14-15 are zeros)

// Note:

Stage 2 is symmetric about coefficient 13.

See the example filters for more information.

byte reg19 = (byte)(coeffs.Count == 128 ? 0 : 128);

for (int i = 0; i < coeffs.Count; i++)

{

// stage 1 contains 128 coefficients, while stage 2 contains 16 coefficients

registers.WriteRegister(19, (byte)(reg26 + i));

// write the coefficient data

registers.WriteRegister(20, (byte)(coeffs[i] &0xff));

registers.WriteRegister(21, (byte)((coeffs[i] >>8) &0xff));

registers.WriteRegister(22, (byte)((coeffs[i] >>16) &0xff));

registers.WriteRegister(23, 0x02);// set the write enable bit

}

// disable the write enable bit when’we're done

registers.WriteRegister(23, (byte)(setEvenBit ? 0x04 : 0x00));