TFT LCD Interface Signals

Sharp’s LH79520 System-On-Chip design has an integrated LCD controller. It is able to directly interface to several different types of LCDs — STN, TFT and HR-TFT — without need for a separate LCD controller chip. This device will be used as an example of the LCD interface signals required. LCD panels unfortunately follow no uniform signal naming convention nor pin arrangement, so different LCD panels from different manufacturers will frequently have different pin arrangements and naming conventions. Pairing a Controller with an LCD will become much easier once the required types of signals can be known and understood. The table shows a TFT LCD signal and pin description from a typical LCD manual. The example used here is the Sharp LQ057Q3DC02.

The interface signals follow three categories: control signals, data signals, and power connections.

• Control Signals: The example in the table shows control signals common to all LCD panels; again, they may differ by type and manufacturer.
• Clock signals (CK): for shifting RGB data into the LCD panel.
• Horizontal Synchronization signals (Hsync): There are ‘N’ number of CK periods per Hsync period where ‘N’ is the number of RGB pixels in a line. This signal marks the point at which the current line ends, and the new line begins.
• Vertical Synchronization signals (Vsync): There are ‘M’ number of Hsync periods per Vsync period where ‘M’ is the number of vertical lines in the display. This signal marks the point at which the current frame ends, and the new frame begins.

Other control signals for this TFT LCD are:

• ENAB: Enable signal
• R/L: Right or Left scan direction select
• U/D: Up or Down scan direction select
• V/Q: VGA or QVGA select

Data Signals The data signals are:

• Blue[5:0]
• Green[5:0]
• Red[5:0]