TLC32046MFKB datasheet(30/56 Pages) TI

30 / 56 page

2–16

Table 2–6. (Sin x)/x Correction Table for fs = 8000 Hz and fs = 9600 Hz

ROLL-OFF ERROR (dB)

f (Hz)

ROLL OFF ERROR (dB)

fs = 8000 Hz

ROLL OFF ERROR (dB)

fs = 9600 Hz

f (Hz)

p1 = – 0.14813

p1 = – 0.1307

p2 = 0.9888

p2 = 0.9951

300

– 0.099

– 0.043

600

– 0.089

– 0.043

900

– 0.054

1200

– 0.002

1500

0.041

1800

0.079

0.043

2100

0.100

0.043

2400

0.091

0.043

2700

– 0.043

3000

– 0.102

– 0.043

2.29 TMS320 Software Requirements

The digital correction filter equation can be written in state variable form as follows:

y(i+1) = y(i) ⋅ k1 + u(i+1) ⋅ k2

Where

k1 = p1

k2 = (1 – p1) p2

y(i) = filter state

u(i+1) = next I/O sample

The coefficients k1 and k2 must be represented as 16-bit integers. The SACH instruction (with the proper

shift) yields the correct result. With the assumption that the TMS320 processor page pointer and memory

configuration are properly initialized, the equation can be executed in seven instructions or seven cycles

with the following program:

ZAC

LT K2

MPY U

LTA K1

MPY Y

APAC

SACH (dma), (shift)

TLC32046MFKB Datasheet(PDF) 30 Page - Texas Instruments

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