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PCD5032H

ADPCM CODEC for digital cordless telephones

Philips Electronics 

Philips Semiconductors

ADPCM CODEC for digital cordless

telephones

Product specification

PCD5032

7.3 Modes of operation

The ADPCM CODEC has a ‘Standby mode’, an ‘Active

mode’ and three operating modes: ‘Normal mode’ and two

loop modes. Table 5 gives details of setting the various

modes via the I2C-bus.

7.3.1 STANDBY MODE

After a reset the ADPCM CODEC will by default be in

standby mode. All I2C-bus settings will be cleared.

Standby mode can also be explicitly set using the code

shown in Table 5.

In standby mode all circuits are switched off, except for the

I2C-bus interface. Before going to standby mode the

PCD5032 performs a reset of the ADPCM transcoder,

digital filters and auxiliary logic functions. The I2C-bus

interface registers are not cleared.

7.3.2 ACTIVE MODE

Active mode is set using the code shown in Table 5. Once

active mode has been set, the ADPCM CODEC is by

default in normal mode, but can explicitly be set to one of

the two test loops or back to normal mode using the codes

shown in Table 5.

7.3.3 TEST LOOPS

Both test loops can be used for test or evaluation

purposes.

Loop 1 is intended for testing the audio path and A/D, D/A

converters, the ADPCM transcoder is not addressed in this

mode. The ADPCM data is directly looped back towards

the radio interface.

The PCM data is looped from transmit filter output to

receive filter input.

Loop 2 is intended for testing the audio path including

ADPCM encoding and decoding.

7.3.4 RESET

After an external reset pulse the circuit will perform an

internal reset procedure. The reset pulse must be active

for at least 10 CLK cycles. 125 µs (the duration of 1 cycle

at 8 kHz) after RESET has gone LOW, the internal reset is

completed and the PCD5032 goes into standby mode.

At that moment the ADPCM CODEC is ready to be

programmed.

A reset clears all I2C-bus registers and resets the ADPCM

transcoder, digital filters and auxiliary logic functions.

Table 5 Modes of operation

FUNCTION

I2C-CODE

Standby mode

Active mode

Normal mode

00XXX0XX

00XXX1XX

00XXXX00

DESCRIPTION

Power-down

Active

Normal operation

Loop 1

Loop 2

00XXXX01

00XXXX10

Loopback on ADPCM side and on PCM side

without using ADPCM transcoder

Loopback on TM+/TM− through ADPCM

transcoder

NOTE

default after reset

default after active

mode set

handbook, full pagewidth0 0 1 0 1 0 1 1 1 1 0 1 0 1 0 0 0 0 −1 0 −1 0 −1 −1 −1 −1 0 −1 0 −1 0 0

+VDD

0

−VDD

MGK072

Fig.9 Tone output example.

1997 Apr 03

12

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