July 1993

9

Philips Semiconductors

Product specification

Terrestrial Digital Sound Decoder (TDSD2)

SAA7282

Slave Transmitter

The slave transmitter formats are illustrated thus:

• S SLAVE_ADDR.1 A STATUS_BYTE NA P

In this format the bus master reads the STATUS_BYTE once.

• S SLAVE_ADDR.1 A STATUS_BYTE A ERROR_BYTE NA P

In this format the bus master reads two bytes of STATUS_BYTE and ERROR_BYTE.

• S SLAVE_ADDR.1 A STATUS_BYTE A ERROR_BYTE A AD_BYTE_0 A AD_BYTE_1 NA P

In this format the bus master reads four bytes of STATUS_BYTE, ERROR BYTE and two additional bytes, AD_BYTE_0

and AD_BYTE_1. The additional data bytes contain the eleven additional data bits AD0 to AD10 together with

information regarding their status.

Where NA = no acknowledge.

Table 5

Data byte formats.

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

STATUS_BYTE

PONRES

S/MD/S

VDSP

RSSF

OS

AM

CFC

ERROR_BYTE

E7

E6

E5

E4

E3

E2

E1

E0

AD_BYTE_0

AD7

AD6

AD5

AD4

AD3

AD2

AD1

AD0

AD_BYTE_1

OVW

SAD

0

CI2

CI1

AD10

AD9

AD8

The bits may be defined as follows:

PONRES

This bit is a power-on reset detection bit. It is set HIGH

after a power-on reset or supply reduction and is cleared

LOW when the STATUS_BYTE is read.

S/M (stereo/mono indication)

S/M = logic 1 indicating an incoming stereo transmission.

S/M = logic 0 indicating that the incoming transmission is

not stereo.

D/S (dual/single mono indication)

D/S = logic 1 indicating an incoming dual mono

transmission.

D/S = logic 0 indicating that the incoming transmission is

not dual mono.

VDSP

This bit indicates that the decoded signal is valid digital

sound. When VDSP = logic 0 the incoming transmission

carries either a 704 kbit/s transparent data channel or a

currently undefined format and the device automatically

switches to FM regardless of RSSF.

RSSF

RSSF is the reserve sound switching flag indication equal

to the C4 bit in the NICAM transmission. RSSF = logic 1

when the FM sound signal is carrying the same

programme material as the digitally modulated carrier

(specifically the M1 signal in the event of a dual mono

transmission). RSSF = logic 0 when the FM signal is not

reproduced within the digital signal.

OS

This bit provides an active LOW indication that the decoder

is out of sync. If OS = logic 1 the decoder is frame

synchronized and has obtained C0 (16 frame) sync.

If OS = logic 0, the decoder is out of sync and the indicator

bits are as given in Table 6.

AM

This bit indicates when the automuting function has

switched from the NICAM sound to the conventional FM

sound. This enables the software controller to display the

relevant information to the customer, for example, on

screen display. If AM bit = logic 0 no switching has been

carried out by the automuting function. If AM bit = logic 1

then the automuting function has switched to the FM

inputs.