83C145 Datasheet, PDF (24/40 Pages) NXP Semiconductors – Microcontrollers for TV and video MTV

Philips Semiconductors
Microcontrollers for TV and video (MTV)
Product specification
83C145; 83C845
83C055; 87C055
Table 28 Shadowing modes determined by bits SHM2 to SHM0 (register OSMOD) and Sh (register OSAT)
SHM2
SHM1
SHM0
Sh
SHADOWING MODE⁽¹⁾
0
0
0
1
South-west
0
0
1
1
West
0
1
0
1
North-west
0
1
1
1
North
1
0
0
1
North-east
1
0
1
1
East
1
1
0
1
South-east
1
1
1
1
Full surround
X
X
X
0
No Shadowing
Note
1. The mode names are based on the position of an apparent light source, ranging from the lower left (South-west)
clockwise to the lower right (South-east); see Fig.8.
13.9 OSD Control Register OSORG
Table 29 OSD Control Register OSORG (address C2H)
7
6
5
4
3
2
1
0
HS4
HS3
HS2
HS1
HS0
VS2
VS1
VS0
Table 30 Description of OSORG bits (note 1)
BIT
7 to 3
2 to 0
SYMBOL
DESCRIPTION
HS4 to HS0 HStart field; defines the horizontal start position of all the on-screen character rows, as
approximately a multiple of 4 VCLK clock cycles. Active display begins after the trailing
edge of HSYNC at the position:
HP = [4 × (HStart) + 1] × VCLK clock cycle + (one single-sized character width)
VS2 to VS0
Where (HStart) is the decimal value of bits (HS4 to HS0); note 2.
VStart field; defines the vertical start position of the first on-screen character row, as
approximately a multiple of 4 HSYNC pulses. Active display begins after the field’s time
reference point (a range of 3 to 31)at the position:
VP = [4 × (VStart) – 1] × HSYNC pulses
Where (VStart) is the decimal value of bits (VS2 to VS0); note 3.
Notes
1. Neither the Hstart nor Vstart parameter is affected by the D line attribute that is used to display double-sized
characters.
2. Counting variations in Wc, there may be 17 to 143 VCLK clock cycles from the end of HSYNC to the start of the first
character of each row.
3. Subsequent character rows occur directly below the first, such that the last scan line of one row is directly followed
by the first scan line of the next row. Successive New Line characters (with or without the Short Row designation)
can be used to vertically separate text rows on the screen.
1996 Mar 22
24