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VII LCD CONTROLLER BLOCK: LCD CONTROLLER
7. If necessary, select the pixel clock frequency for use in portrait mode by using the PMODCLK[1:0]
(D[1:0])/portrait mode register (0x39FFFB). Note that, in alternate portrait mode, the pixel clock
frequency is halved compared to that in landscape mode, without specifically changing register settings.
Therefore, the frame rate must be reviewed, including resetting of the non-display-period parameter. For
details on calculating the frame rate, refer to "Frame Rate".
PMODCLK1
CLK denotes the LCDC clock selected using the LCLKSEL[2:0] (D[2:0])/FIFO control register
(0x39FFF4).
8. Set alternate portrait mode.
PMODEN (D7)/portrait-mode register (0x39FFFB) = "1"
PMODSEL (D6)/portrait-mode register (0x39FFFB) = "1"
Upon completion of the above setting, the display mode is switched to portrait mode.
When using an LCD panel with a vertical resolution of less than 256 lines, a virtual screen similar to the one
in default portrait mode can be configured. The screen can be panned or scrolled by setting a value (including
offset) in the line byte count register, and then controlling the screen 1 start address register.
In alternate portrait mode, the screen can be scrolled in the vertical direction one line at a time.
Comparison of portrait modes
The differences between default portrait mode and alternate portrait mode are summarized in Table 2.16.
Parameter
Display
memory
Clock
Power
consumption
Vertical scroll
Display
performance
B-VII-2-28
Table 2.15 Clock Settings for Alternate Portrait Mode
PMODCLK0
0
0
0
1
1
0
1
1
Table 2.16 Differences between Portrait Modes
Default portrait mode
Sufficient display memory must be available
so that the horizontal size following rotation
is the original value to the power of 2. In
many cases, that value differs from the LCD
panel size, and an unused area occurs
unless the value is used as a virtual screen.
To display a 240
320-pixel image by
rotating a 320
240-pixel LCD panel 90
degrees, for example, as much display
memory as for a horizontal size of 2
pixels must be available. For 8-bpp mode,
this is normally 320
240 = 76,800 bytes,
but for portrait display, 256
bytes are required.
MCLK for display memory access and the
pixel clock PCLK for LCD display may be
used at the same speed.
The LCD controller can operate at low
power.
Can be scrolled two lines at a time.
Standard performance.
Pixel clock PCLK
Memory clock MCLK
CLK/2
CLK/2
CLK/4
CLK/8
If a virtual screen is not being configured, no
memory area other than that for the image
size is required.
8
= 256
320 = 81,920
MCLK must be twice as fast as PCLK.
PCLK cannot be set to above 12.5 MHz.
A greater amount of power than in default
portrait mode is consumed.
Can be scrolled one line at a time.
Higher performance than default portrait
mode.
EPSON
CLK
CLK
CLK/2
CLK/4
Alternate portrait mode
S1C33L03 FUNCTION PART
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