RS_Color liquid crystal display controller (CLCD)
RM0082
750/844
Doc ID 018672 Rev 1
Horizontal timing restrictions
DMA requests new data at the start of a horizontal display line. Some time must be allowed
for the DMA transfer and for the data to propagate down the FIFO path in the LCD interface.
The data path latency forces some restrictions on the usable minimum values for horizontal
porch width in STN mode.
The minimum values are HSW = 2 and HBP = 2.
Single panel mode:
●
HSW = 3
●
HBP = 5
●
HFP = 5
●
Panel clock divisor (PCD) = 1 (CLCDCLK/3).
Table 676.
LCDTiming0 register bit assignments
Bit
Name
Reset
value
Description
[31:24]
HBP
8’h0
Horizontal back porch is the number of
CLCP
periods between the falling edge of
CLLP
and the
start of active data. Program with value minus 1.
The 8 bit HBP field specifies the number of pixel
clock periods inserted at the beginning of each line
or row of pixels. After the line clock for the previous
line has been deasserted, the value in HBP counts
the number of pixel clocks to wait before starting
the next display line. HBP can generate a delay of
1-256 pixel clock cycles.
[23:16]
HFP
8’h0
Horizontal front porch is the number of
CLCP
periods between the end of active data and the
rising edge of
CLLP
. Program with value minus 1.
The 8 bit HFP field sets the number of pixel clock
intervals at the end of each line or row of pixels,
before the LCD line clock is pulsed. When a
complete line of pixels is transmitted to the LCD
driver, the value in HFP counts the number of pixel
clocks to wait before asserting the line clock. HFP
can generate a period of 1-256 pixel clock cycles.
[15:08]
HSW
8’h0
Horizontal synchronization pulse width is the width
of the
CLLP
signal in
CLCP
periods. Program with
value minus 1. The 8 bit HSW field specifies the
pulse width of the line clock in passive mode, or
the horizontal synchronization pulse in active
mode.
[07:02]
PPL
6’h0
Pixels-per-line. Actual pixels-per-line = 16 * (PPL +
1). The PPL bit field specifies the number of pixels
in each line or row of the screen. PPL is a 6 bit
value that represents between 16 and 1 024 PPL.
PPL controls how much data is read from the DMA
input buffers through to the gray scaler.
[01:00]
-
-
Reserved, do not modify, read as zero, write as
zero.