peb20560 Infineon Technologies Corporation, peb20560 Datasheet - Page 160

• Manufacturer Part Number: peb20560
• Description: Dsp Oriented Pbx Controller Doc
• Manufacturer: Infineon Technologies Corporation

Semiconductor Group
Circular-buffer write/read address in mode 5
Mode 5 is a test mode for testing the PEDIU ROM and the PEDIU RAM (circular buffer).
In this mode the DSP can access any address of the circular buffer without any
limitations for read or write operation. The internal circular-buffer address, in this mode,
is the 8 lsbs of DXAP (DXAP7…0) without any conversion, and it can be any address
from 0 to FF
circular buffer: F0
2.8.6
In voice systems, two companding/expanding laws are used:
• µ-law following the BELL specification is used in USA, Canada, Japan and
• a-law following the CCITT specification is used in Europe and in other countries.
The DOC supports both conversion techniques by an integrated hardware logic. This
hardware logic is a part of the PEDIU, and enables conversion from linear to a-/µ-law
and from a-/µ-law to linear. This section specifies the a-/µ-law coding/decoding, as they
are implemented in the DOC, within the PEDIU.
In both, a-law and µ-law, the 8 bit digital code (the logarithmic data) has a sign-bit, P,
three bits of segment, S2S1S0, and 4 bits, Q3Q2Q1Q0, for step selection within the
chosen segment.
bit
In µ-law, the 8 bit digital code is encoded/decoded from/to a 14 bit linear data, when the
msb is the sign-bit. Since the OAK (DSP) data word is 16 bit long, these 14 bit are
inserted in the 14 msbs:.
bit
In a-law, the 8 bit digital code is encoded/decoded from/to a 13 bit linear data, when the
msb is the sign-bit. Since the OAK (DSP) data word is 16 bit long, these 13 bit are
inserted in the 13 msbs:.
bit
Philippines,
15
15
7
P
14
14
a-/µ-law Conversion
H
. here, also, bits 15…8 of the DSP address should contain the prefix of the
13
13
6
H
.
S2
12
12
11
11
5
a-law 13 bit signed data
µ-law 14 bit signed data
S1
10
10
9
9
4
S1
2-114
8
8
3
7
7
Q3
6
6
Functional Block Description
5
5
2
Q2
4
4
1
3
3
Q1
2
2
0
PEB 20560
0
1
1
0
0
2003-08
Q0
0
0
0
0