GENERAL DESCRIPTION

The SAA5250 is a CMOS Interface for Data Acquisition and Control (CIDAC) designed for use in conjunction with the Video Input Processor (SAA5230) in a multi-standard teletext decoder. The device retrieves data from a user selected channel (channel demultiplexer), as well as providing control signals and consecutive addressing space necessary to drive a 2 K bytes buffer memory.

The system operates in accordance with the following transmission standards:

• French Didon Antiope specification D2 A4-2 (DIDON)

• North American Broadcast Teletext specification (NABTS)

• U.K. teletext (CEEFAX)

Features

• 7,5 MHz maximum conversion rate

• Three prefixes; DIDON, NABTS and U.K. teletext (CEEFAX)

• Mode without prefix

• Internal calculation of the validation (VAL) and colour burst blanking (CBB) signals, if programmed

• Programmable framing code and channel numbers

• Error parity calculation or not (odd parity)

• Hamming processing of the prefix byte

• Full channel or VBI reception

• Slow/fast mode (detection of page flags or not)

• Maximum/default format up to 63 bytes

• Addressing space of 2 K bytes of the static memory

• Multiplexed address/data information is compatible with Motorola or Intel microcontrollers

• CIDAC is ‘MOTEL’ compatible