RS_Color liquid crystal display controller (CLCD)
RM0082
752/844
Doc ID 018672 Rev 1
33.6.6
LCD timing 2 register
LCDTiming2 is a read/write (RW) register that controls the CLCD timing.
shows
the bit assignments for the LCDTiming2 register.
[15:10]
VSW
6’h0
Vertical synchronization pulse width is the number
of horizontal synchronization lines. Must be small
(for example, program to zero) for passive STN
LCDs. Program to the number of lines required
minus one. The higher the value the worse the
contrast on STN LCDs. The 6 bit VSW field
specifies the pulse width of the vertical
synchronization pulse. The register is programmed
with the number of line clocks in VSync minus one.
Number of horizontal synchronization lines. Must
be small (for example, program to 0) for passive
STN LCDs. Program to the number of lines
required minus 1. The higher the value the worse
the contrast on STN LCDs.
[09:00]
LPP
10’h0
Lines per panel is the number of active lines per
screen. Program to number of lines required minus
1. The LPP field specifies the total number of lines
or rows on the LCD panel being controlled. LPP is
a 10 bit value that allows 1-1 024 lines. The
register is programmed with the number of lines
per LCD panel minus 1. For dual panel displays
this register is programmed with the number of
lines on each of the upper and lower panels.
Table 677.
LCDTiming1 register bit assignments (continued)
Bit
Name
Reset
value
Description
Table 678.
LCDTiming2 register bit assignments
Bit
Name
Reset
value
Description
[31:27]
PCD_HI
5’h0
Upper five bits of panel clock divisor.a The ten bit PCD field,
comprising PCD_HI and PCD_LO (bits [4:0]), is used to derive
the LCD panel clock frequency CLCP from the CLCDCLK
frequency:
CLCP = CLCDCLK/(PCD+2).
For mono STN displays with a four or eight bit interface, the
panel clock is a factor of four and eight down on the actual
individual pixel clock rate. For color STN displays, 2 2/3 pixels
are output per CLCP cycle, therefore the panel clock is 0.375
times.
For TFT displays the pixel clock divider can be bypassed by
setting the LCDTiming2[26] BCD bit.
[26]
BCD
1’h0
Bypass pixel clock divider. Setting this to 1 bypasses the pixel
clock divider logic. This is mainly used for TFT displays.