Motorola MPC823e - Page 519

Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-65
DSP
COMMUNICATION
16
PROCESSOR MODULE
16.3.4.8.4 Application Example. The DEMOD is used in the modulator. The following
example demonstrates how the function descriptor structure can be used to implement the
MOD function.
16.3.4.9 LMS1–COMPLEX COEFFICIENTS, COMPLEX SAMPLES, AND
REAL/COMPLEX SCALAR . The LMS1 function implements a basic FIR filter coefficients
update. The coefficients and input samples are complex numbers, but the scalar is a real or
complex number.
16.3.4.9.1 Coefficients and Sample Data Buffers. The coefficients vector occupies k
pairs of 16-bit half-words (real and imaginary components) in memory and C(0) is stored in
the first location. The samples input buffer is a cyclic buffer that contain M+1 bytes. Each
sample is a pair of 16-bit half-words (real and imaginary components) and the new sample
is stored in the address that follows the previous sample.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
OFFSET + 0
S0WI0000000 01001
OFFSET + 2
I=3 (THREE ITERATIONS)
Figure 16-28. LMS1 Implementation Example
COEFFICIENTS INPUT SAMPLES
imag{C(0)} *
real{C(0)} *
imag{C(1)} *
real{C(1)} imag{X(n-k+1)}
* real{X(n-k+1)}
**
imag{C(k-1)} *
real{C(k-1)} imag{X(n-2)}
real{X(n-2)}
imag{X(n-1)}
real{X(n-1)}
imag{X(n)}
real{X(n)}
2K bytes M + 1 bytes
Figure 16-29. LMS1 Coefficients and Sample Data Buffers
C
n1+
i
C
n
i
EX
ni –
× +=