Display Data Output Formats - NEC µPD72257 Preliminary User's Manual

Chapter 7
Table 7-2
Table 7-3
31 30 29
15 14 13
VOnLCDCONTROL.BRG = 0: normal RGB output
I R4 R3 R2
VOnLCDCONTROL.BRG = 1: swapped BGR output
I B4 B3 B2
Note

7.2.2 Display data output formats

192
Due to the 128 x 32 bit organization of the CLUT RAM, two output values are
combined to a single RAM word, as shown below.
CLUT palette RAM organization
Bit 31
Word 0
Word 1
...
Word
127
The bit assignment of each iRGB(1555) value is show below.
The R[4:0] and B[4:0] can be swapped by the control bit VOnLCDCONTROL.BGR.
CLUT iRGB(1555) format
28 27 26 25
12 11 10 9
R1 R0 G4
B1 B0 G4
The CLUT palette RAM is preloaded via the Host CPU via the 128 32-bit registers
VOnLCDPALETTE[127:0]. Two entries can be written into the palette from a single
word write access.
The intensity bit written to the CLUT can be constructed as an OR combination
of the LSB of all colours,
i.e. I = VOnR0 or VOnG0 or VOnB0.
The display data output format is either 18 bpp RGB(666) or 16 bpp RGB(565).
Depending on the colour mode some signals have different meaning. The colour
mode is defined by the VOnLCDCONTROL.LCDBPP[2:0] bits.
In 8 bpp CLUT(8) mode, that outputs iRGB(1555) data, the intensity bit I is output
as the LSB of all colours, i.e. VOnR0 = VOnG0 = VOnB0 = I.
In 16 bpp RGB(565) true colour mode, the LSBs of the red (VOnR0) and blue
channel (VOnB0) are undefined.
In 18 bpp RGB(666) true colour mode, all colour channels are output in maximum
resolution.
Below table shows the signals output on the external display data bus with regard
to the different modes.
Preliminary User's Manual S19203EE1V3UM00
16
colour 1
colour 3
...
colour 255
24 23 22 21
8 7 6 5
G3 G2 G1 G0
G3 G2 G1 G0
Video Output
15
colour 0
colour 2
...
colour 254
20 19 18 17
4 3 2 1
B4 B3 B2 B1
R4 R3 R2 R1
0
16
0
B0
R0