saa5252 NXP Semiconductors, saa5252 Datasheet - Page 15

• Manufacturer Part Number: saa5252
• Description: Line Twenty-one Acquisition Display Litod
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Interface to microcontroller using I
The interface to the microcontroller is via the two-wire
serial I
(DR). On power up the microcontroller initializes the
device by an I
(Control Byte 1). The I
incremented to point to Register 1 (Control Byte 2). These
two registers configure the device to the users
requirements.
If the device is to be used for data acquisition only, then
there are three methods by which the microcontroller can
be informed of the arrival of valid Line 21 data:
When valid data is detected, the microcontroller must
initiate an I
The first and second data bytes from the most recently
received Line 21 are in Register 81H and Register 82H
respectively.
The DR pin, and the Data Ready bit (Status bit D0) will be
cleared after any register has been read. POR is reset
after Register 80H has been read.
1996 Jul 18
It can poll the DR pin, if the function has been enabled,
and wait for it to go LOW.
It can use the negative edge of the DR signal to cause
an interrupt.
It can poll the Data Ready bit (bit D0 of the status byte,
I
Line twenty-one acquisition and display (LITOD)
2
C-bus READ Register 0).
2
C-bus, and optionally by a Data-Ready signal
2
C-bus READ of Registers 80H, 81H and 82H.
2
C-bus WRITE to Registers 0
2
C-bus subaddress is then auto
2
C-bus
15
‘STAND-ALONE’ (NON I
To set the SAA5252 for ‘stand-alone’ operation pin 2
(I
SCL, SDA and DR pins to mode select inputs which will
select as shown in Table 13.
In the caption mode the SAA5252 operates in the basic
Normal character/Black background mode. This complies
with the FCC ruling. In the Enhanced caption mode the
set-up will be Shadowed character/Video background.
SDA and SCL in the ‘stand-alone’ operation act as bits M0
and M1 in Table 8.
Table 13 Stand-alone modes
2
DR
C/DC) is tied LOW. This will change the operation of the
0
0
0
0
1
1
1
1
SCL SDA
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
video mode
text mode
normal captions
enhanced captions Channel 1
video mode
text mode
normal captions
enhanced captions Channel 2
OPERATION
MODE OF
2
C-BUS) OPERATION
Product specification
SAA5252
Channel 1
Channel 1
Channel 1
Channel 2
Channel 2
Channel 2
RECEPTION
CHANNEL