UM0304

Block FIR 16-bit filter

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the filter coefficients are a multiple of 6 - more information is available in the source code.

The source code module may be found in DSPLIB.

3.6

Requirements

A caller needs to organize an input vectors say x[] and output vector say y[] for filter. The

caller needs to design the filter coefficients using any of the windowing functions such as

Hamming, Hanning, and Blackman etc as required by the filter response.

Then upon designing the coefficients, reverse the order of the coefficients. The number of

coefficients, T, must be an integer multiple of 6.

3.7

Implementation

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The filter needs T number of coefficients and T is multiple of 6

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The output vector y[N] is such that N equals (2 * T)

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The input vector x[M] is such that M equals (N + T - 1)

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The code is little ENDIAN

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The code is interrupt-tolerant but not interruptible

3.8

Benchmarking

The benchmarking for this filter function is done using Chameleon Trace while the filter

function is running in STR91x engine with ARM966E-S. For the Chameleon Trace in ETM

Configuration Trace Port Size is set to 8 bit and Trace Port Mode is set to Normal, Half-rate

clocking, while the STR91x engine runs at 96 MHz.

Table 3.

Benchmarking of Block FIR algorithm module

Number of taps

Cycle count

Microseconds

72

15063

156.854

48

6842

71.271

24

1813

18.885