saa5290 NXP Semiconductors, saa5290 Datasheet - Page 25

• Manufacturer Part Number: saa5290
• Description: Page Economy Teletext/tv Microcontroller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
R
Row 0 is for the page header. The first seven characters
(0 to 6) are free for status messages. Character 8 is an
alphanumeric white or green control character, written
automatically by SAA5290 to give a green rolling header
when a page is being looked for. The last eight characters
are for rolling time.
R
The first 10 bytes of row 25 contain control data relating to
the received page as shown in Table 14. The remaining 14
bytes are free for use by the microcontroller.
Extension packet memory organization
If TXT0.X24 POS bit is set to logic 0, then Packet 24 is
written into Row 0 of the extension memory.
Packet X27/0 is written to Row 1 of the extension memory,
with bytes 0 to 37 being Hamming checked automatically.
Packet 8/30 is written to Row 2 of the extension memory,
with bytes 0 to 6 being 8/4 Hamming checked, bytes
7 to 19 unchecked and bytes 20 to 39 odd parity checked.
February 1995
OW
OW
handbook, full pagewidth
One page Economy Teletext/TV
microcontroller
0 (see Fig.5)
25 (see Fig.5)
7 characters
1
for status
page information
10 bytes for
received
10
Fig.5 Basic page memory organization.
6
PACKET X24 STORED HERE IF TXT0.7 = 1
7 8
hardware, alphanumerics white nor-
24 characters from page header
rolling when display page looked for
mally, alphanumerics green when
MAIN PAGE DISPLAY AREA
fixed character written by
looking for display page
by microcontroller
PACKET X / 22
PACKET X / 23
free for use
14 bytes
14
25
Packet 26 processing
The SAA5290 contains on-board hardware processing of
Packet 26 data. If a character corresponding to that being
transmitted is available in the character set then the
correct character code is written into the display memory.
handbook, halfpage
Fig.6 Organization of the extension memory.
PACKET X24 if TXT0.X24 POS = 0
PACKET X27 / 0
PACKETS 8 / 30 / 0 to 15
31 32
usually rolling
8 characters
(time)
MLC106
39
ROW
20
21
22
23
24
25
to
0
1
2
3
4
5
Preliminary specification
MLC107
SAA5290
ROW
0
1
2