saa6713h NXP Semiconductors, saa6713h Datasheet - Page 73

• Manufacturer Part Number: saa6713h
• Description: Xga Dual Input Flat Panel Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
The access to the graphic memory is based on a masked
writing with pixel exact addressing (see Fig.23) via the
write cursor (OSDB_CX, OSDB_CY) always configuring
8 bits at a time (OSDB_DEF) with data being processed
from left to right and top to bottom. Using the
8 corresponding mask bits (OSDB_MASK) any pixel within
the OSD bitmap can directly be accessed and redefined
without changing neighbouring pixel also during display
time allowing software guided animations for fancy
start-up screens. Both the OSDB_DEF and OSDB_MASK
are always MSB aligned which means that bit 7 will be
written to the pixel address that is referenced by the OSD
bitmap cursor (OSDB_CX, OSDB_CY). Depending on the
selected bitmap size and the number of colours to be used
this pixel address will probable not be byte aligned but the
user does not have to take care of any internal alignments.
The next 8 bits that are written to OSDB_DEF will be
written bit wise starting with the MSB from the given cursor
location.
2004 Apr 05
handbook, full pagewidth
XGA dual input flat panel controller
(bits per pixel code = 00)
byte 2
start position of configuration: OSDB_CX = 4, OSDB_CY = 6
OSD bitmap defined with OSDB_SX = 14 and OSDB_SY = 19
byte 4
2 colour definition
1 bit per pixel
byte 1
...
byte 3
Fig.23 Data format of the OSD bitmap RAM.
3
(bits per pixel code = 01)
byte 4
4 colour definition
2 bits per pixel
byte 1
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...
In order to speed up the OSD bitmap definitions the
internal RAM address is incremented by 8 bits always
when a write to OSDB_DEF happened. Together with a
stop of the SAA6713H register auto-increment at this
register, this allows a fast burst configuration of multiple
pixel up to a complete OSD bitmap definition setting the
cursor to (0,0), the mask to FFH and writing all needed
data bytes in a single burst. The number of needed byte
transmissions is derived by multiplying the total number of
pixels to be configured with the used bits per pixel and
dividing this result by 8 bits. When overwriting parts of the
bitmap image the user must handle the OSDB_MASK
flags for the remaining bits that shall not overwrite any data
by himself.
byte 2
byte
(bits per pixel code = 1X)
16 colour definition
4 bits per pixel
b1 b2
Product specification
b3
SAA6713H
b4
MHC230