Filter
Top Products
VII LCD CONTROLLER BLOCK: LCD CONTROLLER
S1C33L03 FUNCTION PART EPSON B-VII-2-21
A-1
B-VII
LCDC
Display Control
Controlling LCD Power Up/Down
The LCD controller is activated to start up and generate LCD signals by setting LCDCEN (D5)/LCDC mode
register 2 (0x39FFE3) to "1". Setting LCDCEN to "0" causes the LCD controller to stop operating, with the LCD
signal output dropped low. For the LCD controller to start display correctly, the LCD-panel parameters and display
data must be set before LCDCEN is set to "1".
If the power to the LCD panel is turned on or off while LCD signals are not being correctly output, the panel may
be damaged. Therefore, the power to the LCD panel must be turned on only after the LCD panel starts controlling
LCD signals. The signal used to control the power to the LCD panel for this purpose is LCDPWR. Once the output
pin for it is enabled, LCDPWR output is controlled in the hardware during the LCD power-up and power-down
sequences of the LCD controller. When LCD signals have no effect, the LCDPWR signal goes low; when LCD
signals become effective, the LCDPWR signal goes high. Controlling the power to the LCD panel using this signal
ensures that the LCD panel is powered up and powered down safely.
Control of the LCDPWR pin by the LCD controller is enabled by setting LPWREN (D4)/LCDC mode register 2
(0x39FFE3) to "1".
Following power-on, the LCD controller is set in such a way that LCDCEN = "0" and power-save mode is on.
Setting LCDCEN to "1" does not immediately cause the LCD panel to initiate a power-up sequence and start
displaying data. The LCD panel is placed in power-save mode, with all LCD signal output pins fixed low. The
LCDPWR signal is also fixed low, and the power to the LCD panel does not turn on.
To change the LCD controller from power-save mode back into normal mode, set LPSAVE[1:0] (D[1:0])/LCDC
mode register 2 (0x39FFE3) to "0b11". The LCD controller starts a power-up sequence from that point, and
outputs LCD signals while driving the LCDPWR signal high (to turn on the power to the LCD panel). This power-
up sequence requires a one-frame period. Conversely, to change from normal mode to power-save mode, set
LPSAVE to "0b00". The LCD controller starts a power-down sequence from that point, and pulls the LCDPWR
signal low a one-frame period later (to turn off the power to the LCD panel) while driving the LCD signals low.
In power-save mode, furthermore, although the LCD control registers can be set, the look-up tables cannot be
accessed. Before setting the look-up tables following power-on, place the LCD controller in normal mode.
The procedure for initializing the LCD at power-on is summarized below.
1. Set the BCU, clock, and display memory area (refer to "System Settings").
2. Set the LCD-panel parameters and display mode (refer to "Setting the LCD Panel").
3. Write display data to the display memory.
4. Set the display start address (refer to "Setting the Display Start Address").
5. Enable control of the LCDPWR signal (LPWREN = "1").
6. Enable the LCD controller (LCDCEN = "1").
7. Place the LCD controller in normal mode (LPSAVE = "0b11").
8. The LCD controller starts a power-up sequence and the power to the LCD panel turns on a one-frame period
later.
9. Set the look-up tables (refer to "Look-up Tables").
Thus, the above is the basic operation for starting up the display.