Teac TFT IDTV, Service Manual

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13
22” TFT TV Service Manual 13/10/2004
11.10. SDA55XX (SDA5550)
11.10.1. General description
The SDA55XX is a single chip teletext decoder for decoding World System Teletext data as well as Video
Programming System (VPS), Program Delivery Control (PDC), and Wide Screen Signalling (WSS) data
used for PAL plus transmissions (Line 23). The device also supports Closed caption acquisition and
decoding. The device provides an integrated general-purpose, fully 8051-compatible Microcontroller with
television specific hardware features. Microcontroller has been enhanced to provide powerful features such
as memory banking, data pointers, and additional interrupts etc. The on-chip display unit for displaying
Level 1.5 teletext data can also be used for customer defined on screen displays. Internal XRAM consists
of up to16 Kbytes. Device has an internal ROM of up to 128 KBytes. ROMless versions can access up to 1
MByte of external RAM and ROM. The SDA 55XX supports a wide range of standards including PAL,
NTSC and contains a digital slicer for VPS, WSS, PDC, TTX and Closed Caption, an accelerating
acquisition hardware module, a display generator for Level 1.5 TTX data and powerful On screen Display
capabilities based on parallel attributes, and Pixel oriented characters (DRCS).
The 8-bit Microcontroller runs at 360 ns. cycle time (min.). Controller with dedicated hardware does most of
the internal TTX acquisition processing, transfers data to/from external memory interface and receives/
transmits data via I
2
C-firmware user-interface. The slicer combined with dedicated hardware stores TTX
data in a VBI buffer of 1 Kilobyte. The Microcontroller firmware performs all the acquisition tasks (hamming
and parity-checks, page search and evaluation of header control bits) once per field. Additionally, the
firmware can provide high-end Teletext features like Packet-26-handling, FLOF, TOP and list-pages. The
interface to user software is optimized for minimal overhead. SDA 55XX is realized in 0.25 micron
technology with 2.5 V supply voltage and 3.3 V I/O (TTL compatible). The software and hardware
development environment (TEAM) is available to simplify and speed up the development of the software
and On Screen Display. TEAM stands for TVT Expert Application Maker. It improves the TV controller
software quality in following aspects:
– Shorter time to market
– Re-usability
– Target independent development
– Verification and validation before targeting
– General test concept
– Graphical interface design requiring minimum programming and controller know how.
– Modular and open tool chain, configurable by customer.