Technicolor - Thomson ICC19, Принципы и обслуживание

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PROCESSING OF TELETEXT AND OSD
Teletext and OSD are completely managed by Microcontroller IT001, assisted
by DRAM IT002.
IT001 is powered at 5 V and controlled by a 20.48-MHz clock. It communicates
with IR001 via Bus M3L (at a rate of 850 kHz). It is configured as slave, and
receives the MRESET initialisation command.
IT001 is a combination Teletext slicer, decoder, and VPS. The slicer separates
Teletext data from the video signal. The IT001 processing unit checks, selects,
and stores the requested data in the DRAM, IT002. A page of data occupies
1 KB of memory on average. IT002 is designed for 512 pages of Teletext.
The data (Teletext) acquisition PLL is locked from the video signal, Pin 9
of IT001. The display (Teletext and OSD) PLL is locked from the line and frame
signals arriving on Pins 3 and 4 of IT001.
The display generator supplies 4-bit words for each pixel and each of the R, G,
and B signals. The R, G, and B signals are then output through Pins 44 through
46 of IT001 via three digital-to-analogue converters. The level of these R, G,
and B signals is proportional to the reference voltage at 16 of IT001. The fast
switching signal, FB (Pin 47) accompanies the R, G, and B signals.
NOTES :
CENTRE DE
FORMATION TECHNIQUE
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