AN2641 Datasheet, PDF (11/37 Pages) STMicroelectronics – Using the color LCD controller

AN2641
CLCD panel programmable parameters
used as an enable that indicates to the LCD panel when valid display data is available.
In active display mode, data is driven onto the LCD data lines at the programmed edge
of CLCP when CLAC is in its active state.
0 = CLAC output pin is active HIGH in TFT mode
1 = CLAC output pin is active LOW in TFT mode
6. Invert panel clock (IPC) bit [13] in the LCD-Timing2 register, used to select the
edge of the panel clock on which pixel data is driven out onto the LCD data lines.
0 = Data is driven on the LCD data lines on the rising edge of CLCP
1 = Data is driven on the LCD data lines on the falling edge of CLCP
7. Invert Horizontal Synchronization (IHS) bit [12] in the LCD-Timing2 register, used
to invert the polarity of the CLLP signal.
0 = CLLP pin is active HIGH and inactive LOW
1 = CLLP pin is active LOW and inactive HIGH
8. Invert Vertical Synchronization (IVS) bit [11] in the LCD-Timing2 register, is used
to invert the polarity of the CLFP signal.
0 = CLFP pin is active HIGH and inactive LOW
1 = CLFP pin is active LOW and inactive HIGH.
9. AC bias pin frequency (ACB) bits [10:6] in the LCD-Timing2 register, applies only
to STN displays, which require the pixel voltage polarity to be periodically reversed to
prevent damage due to DC charge accumulation. Program this field with the required
value minus 1 to apply the number of line clocks between each toggle of the AC bias
pin, CLAC. This field has no effect if the CLCD controller is operating in TFT mode
when the CLAC pin is used as a data enable signal.
2.3
Panel display type
The CLCD controller supports the following types of LCD panels:
● TFT (Thin Film Transistor) display: Active matrix display panels which require a
digital color value of each pixel to be applied to the display data inputs.
● STN (Super Twisted Nematic) display: Passive matrix display panels that require
algorithmic pixel pattern generation to provide pseudo gray scaling on mono or color
creation for display (for which a dedicated hardware element, grey scalar, is provided).
Table 1. Different display types and their properties
LCD type
Single/dual panel
Palettized/non-
palettized
Mono/color
TFT
Single
Non-Palettized Color
TFT
Single
Non-Palettized Color
TFT
Single
Palettized
Color
STN
Single and Dual Non-Palettized Color
STN
STN
Single and Dual
Single and Dual
Palettized
Palettized
Color
Mono
BPP
24
16
1, 2, 4 and 8
16
1, 2, 4 and 8
1,2 and 4
Doc ID 14027 Rev 1
11/37