Control Registers Details - NEC µPD72257 Preliminary User's Manual

Drawing Engine

8.9.2 Control registers details

8.9.2.1
Access
Address
Index
Initial Value
Bit Bit name
23 SPANSTORE
22 SPANABORT
21 UNIONCD
20 UNIONAB
DRWCONTROL - Geometry control register
This register controls the pixel enumeration and selection units, deciding which
pixels are part of the geometry.
This register can be written in 32-bit units.
<DrwE_Base> + 00
H
0
0000 0000 . This register is initialized by any reset.
H
31 30
0 0
W W
23 22
SPAN SPAN UNION
STORE ABORT
W W
15 14
LIM6 LIM5
BAND1
THRESH THRESH
ENABLE
OLD OLD
W W
7 6
QUAD2 QUAD1 LIM6
ENABLE ENABLE ENABLE
W W
Wrting to bits marked with "0" is ignored.
Function
Nextline span start is always equal or left to current-line span start
0 disabled
1 enabled
Shape is horizontally convex. only a single span per scanline
0 disabled
1 enabled
Combine outputs C & D as union (output is final)
0 disabled
1 enabled
Combine outputs A & B as union (output is called C)
0 disabled
Preliminary User's Manual S19203EE1V3UM00
29 28 27
0 0 0
W W W
21 20 19
UNION UNION
CD AB 56
W W W
13 12 11
LIM4 LIM3
THRESH THRESH
OLD OLD
W W W
5 4 3
LIM5 LIM4
ENABLE ENABLE
W W W
Chapter 8
26 25 24
0 0 0
W W W
18 17 16
UNION UNION BAND2
34 12 ENABLE
W W W
10 9 8
LIM2 LIM1
QUAD3
THRESH THRESH
ENABLE
OLD OLD
W W W
2 1 0
LIM3 LIM2 LIM1
ENABLE ENABLE ENABLE
W W W
255