PCD5042H datasheet(10/28 Pages) PHILIPS

10 / 28 page

1996 Oct 31

Philips Semiconductors

Objective speciﬁcation

DECT burst mode controller

PCD5042

Fig.4 Internal clocking scheme of the PCD5042.

handbook, full pagewidth

MBH708

480

bit counter

3.456 MHz system

clock for ADPCM codec

slot counter

100 Hz

frame sync

1152 kHz

system/bit clock

clock corrections in this level

unless disabled PCD5041's mode register

COMPARATOR

'SYNC' event

FSx signals

(8 kHz)

slot counter

144

4 (

±1)

13.824 MHz system clock

6.912 MHz system clock

6.4

Speech interface

The speech interface block performs the following

functions:

• Connection to a 1152 kbits/s interface in a handset and

a simple base station in the so called ‘12 slot mode’

• Connection to a n x 64 kbits/s interface in base stations

in the so called ‘32 slot mode’

• Autonomous storing/fetching of ADPCM speech data

in/from the PCD5042’s common data memory, using

internal addressing logic

• Muting of speech data

• Local call.

6.4.1

12-SLOT MODE

The 12-slot mode is selected if up to 4 ADPCM CODECs

are connected to the PCD5042, where the PCD5042 is the

master of these CODECs. In a handset, or in a simple

base stations which is connected with up to 4 analog lines

to the public network, the PCD5042 is master of the

CODECs. Each CODEC is connected with a separate

framing reference signal (FS1 to FS4) to the PCD5042. In

the QFP64 package, 2 framing signals FS1 and FS2 are

available, whereas in the LQFP80 package 4 framing

signals can be used (FS1 to FS4). When more CODECs

are to be connected, the FS5 to FS12 signals have to be

generated externally. When using the framing signals

FS1 to FS4, no interface logic is required when using the

PCD5032 ADPCM CODEC.

A speech-slot control table is used to determine where to

store/fetch speech data for transmission and reception.

The hardware speech-interface is capable of addressing

the right speech buffer for the relevant speech slot, and will

maintain a counter carrying the offset to the correct

stored/fetched address.

6.4.2

32-SLOT MODE

The 32-slot mode is used to connect the PCD5042 to a

digital interface with a data rate of n

× 64 kbits/s; where

n = 1 to 32 is the number of speech slots. This equates to

data rates from 64 kbits/s to 2048 kbits/s.

Up to 12 of the 32 speech slots can be used

simultaneously. The same kind of speech-slot control table

used in the 12-slot mode is used for the 32-slot mode.

6.4.3

MUTING

Due to various reasons the quality of the incoming speech

data may be degraded significantly. By muting the speech

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