Ali Theory Of Operation - Sharp LH79524 User Manual

Color Liquid Crystal Display Controller

4.4.1 ALI Theory of Operation

All ALI Control and Status Registers can be accessed through the APB. One of the regis-
ters, the ALI Setup Register, can be programmed to select Bypass Mode or Active Mode.
• In Bypass Mode, LCD Controller signals are passed directly to the pins.
• In Active Mode, TFT data and control signals from the LCD Controller generate a set of
signals for driving an AD-TFT or HR-TFT display.
Selecting Active Mode re-times the data to the falling edge of the output clock. The format-
ter also provides the:
• Features of normal scanning signals for vertical and horizontal scan
• Generation of source driver, gate driver, and voltage-preparation control signals.
The timing parameters for the Active Mode are register-programmable. When using
Active Mode, program the ALI Setup Register first, followed by ALI Timing registers 1
and 2. After these registers are programmed, the LCD Controller can be enabled and the
ALI Control Register can be used.
The ALI generates the MOD signal automatically. By default, activation of MOD occurs 2
SPS rising edge clocks after activation of the controller. This can be reprogrammed for a
longer or shorter wait, or can be overridden via the ALI Control Register.
4.4.2 ALI Operating Modes
The ALI has two operating modes: Bypass Mode or Active Mode. The ALI Setup Register
setting specifies the operating mode of the ALI (see Section 4.5.6.1).
4.4.2.1 Bypass Mode
Bypass Mode is the default mode after a System Reset. In this mode, the input signals
from the CLCDC are passed directly to the output pins without any signal reformatting. This
mode is used when the LCD Controller is required to operate in normal TFT Mode or when
using the LCD Controller in STN Mode.
4.4.2.2 Active Mode
In Active Mode, TFT data and the control signals from the LCD Controller generate a set
of signals for driving an AD-TFT or HR-TFT display. Active Mode also re-times the data to
the falling edge of the output clock. The formatter provides the scanning signals for vertical
and horizontal scanning. It also generates the source driver, gate driver, and voltage prep-
aration control signals.
4-18 Version 1.0
LH79524/LH79525 User's Guide