SAA5531 Philips Semiconductors, SAA5531 Datasheet - Page 40

• Manufacturer Part Number: SAA5531
• Description: Enhanced TV microcontrollers with On-Screen Display OSD
• Manufacturer: Philips Semiconductors

Philips Semiconductors
17.3.1
The Display memory when in TXT mode (see Fig.15) is
configured as 40 columns wide by 25 rows and occupies
1K
required display page can be selected to be written to.
The row and column within that block is selected using
TXT9.R<4:0> and TXT10.C<5:0>. The data at the
selected position can be read or written using
TXT11.D<7:0>.
Whenever a read or write is performed on TXT11, the row
values stored in TXT9 and column value stored in TXT10
are automatically incremented. For rows 0 to 24 the
column value is incremented up to a maximum of 39, at
which point it resets to zero and increments the row
counter value. When row 25 column 23 is reached the
values of the row and column are both reset to zero.
Table 12 Column and row to ‘MOVX’ address (lower 10 bits of address)
2000 Feb 23
Enhanced TV microcontrollers with
On-Screen Display (OSD)
8-bit of memory. Using TXT15.BLOCK<3:0>, the
Row 23
Row 24
Row 25
TXT
Row 0
Row 1
ROW
:
:
DISPLAY MEMORY
COL.0
2E0H
000H
020H
300H
320H
SFR
:
:
ACCESS
.....
.....
.....
.....
.....
.....
:
:
COL.23
017H
037H
3F7H
317H
337H
:
:
40
Writing values outside of the valid range for TXT9 or
TXT10 will cause undetermined operation of the
auto-incrementing function for accesses to TXT11.
17.3.2
It is important for the generation of OSD displays, that use
this mode of access, to understand the mapping of the
MOVX address onto the display row and column value.
This mapping of row and column onto address is shown in
Table 12. The values shown are added onto a base
address for the required memory block (see Fig.14) to give
a 16-bit address.
.....
.....
.....
.....
.....
:
:
TXT D
COL.31
01FH
03FH
2FFH
31FH
:
:
ISPLAY MEMORY
COL.32
3F8H
3F0H
340H
338H
:
:
MOVX
Preliminary specification
.....
.....
.....
.....
.....
ACCESS
:
:
SAA55xx
COL.39
3FFH
3F7H
347H
33FH
:
: