TDA8961 datasheet(13/36 Pages) PHILIPS

13 / 36 page

2000 May 19

Philips Semiconductors

Objective speciﬁcation

ATSC Digital Terrestrial TV

demodulator/decoder

TDA8961

Transport stream interface

INTRODUCTION

The transport stream interface performs the following

functions:

• Buffers the data from the Reed Solomon decoder and

de-randomizer section

• Inserts the MPEG sync byte at the start of every packet

• Indicates error conditions using a

transport_error_indicator bit in the packet header and

the error signal output PDOERR.

• Outputs either a serial or a parallel output format.

PINNING

The functions of the transport stream interface outputs are

summarized in Table 3. It should be noted that different

source decoder devices may have different uses for the

PDOERR output; its polarity is programmable using

I2C-bus bit FPBP (see Table 14).

PARALLEL OUTPUT FORMAT

Figure 5 shows the timing diagram for the parallel output

format. The PDOSYNC signal indicates the occurrence of

the sync byte in the packet and is only HIGH for one clock

period. The polarity of the PDOVAL and PDOERR signals

is programmable via I2C-bus bits FDVP and FPBP

respectively; Fig.5 shows their default polarities.

The PDOVAL signal is active for the duration of the

188 bytes of the transport stream packet. When the

188 bytes have been transferred, the PDOVAL signal

goes LOW for at least ten PDOCLK cycles during which,

when used with DVB devices, the parity bytes are

transferred; when used with non-DVB devices, zeroed

parity bytes and field sync data are transferred.

The period when the PDOVAL signal is LOW can vary, but

will be a minimum of ten PDOCLK cycles. Due to the

averaging operation of the FIFO, the number of parity

bytes transferred can vary slightly. The PDOCLK signal

runs continuously and is not affected by a reset. In parallel

output format, it has a frequency of 3 MHz.

When the TDA8961 is trying to acquire a channel, the

PDOERR signal goes HIGH (I2C-bus bit FPBP = 1). If this

occurs, the PDOVAL signal stays LOW.

SERIAL OUTPUT FORMAT

Figure 6 shows the timing diagram for the serial output

format. The LSB of the 8-bit PDO data bus is used to

output the MPEG-2 transport stream packets.

The PDOSYNC signal indicates the occurrence of the

sync byte in the packet and is only HIGH during

8 PDOCLK cycles. The polarity of the PDOVAL and

PDOERR signals is programmable via I2C-bus bits FDVP

and FPBP respectively; Fig.6 shows their default

polarities.

The PDOVAL signal is active for the duration of the

188 bytes of the transport stream packet. When the

188 bytes have been transferred, the PDOVAL signal

goes LOW for a period corresponding to the duration of the

parity and field sync information. Figure 6 shows the

PDOERR signal is HIGH for the whole packet length

indicating that the packet contains errors. The PDOCLK

signal has a frequency of 27 MHz.

Table 3

Transport stream interface outputs

All pins are 3-state outputs.

Note

1. In serial output format, only pin PDO0 (LSB) is used to output the data.

SYMBOL

FUNCTION

PDOCLK

clock signal for MPEG-2 packet data bytes (parallel and serial)

PDOVAL

indicates a valid data signal

PDO7 to PDO0

packet data bits 7 to 0 (8-bit wide output bus)(1)

PDOSYNC

indicates the start of a packet; goes HIGH at the start of a packet and stays HIGH during the ﬁrst

byte, otherwise known as the sync byte

PDOERR

indicates packet error; goes HIGH (I2C-bus bit FPBP = 1) for every packet (188 bytes) in which the

Reed Solomon decoder found more errors than it could correct

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