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Direct Drive LCD Design Guide
1.
1.1
Introduction
This document provides technical information of how to configure the LCD panel parameters required by
Renesas LCD Direct Driver according to the LCD panel datasheet published by the manufacturers. This
document will also describe all the APIs (Application Programming Interface) in the LCD Direct Driver and
their usages.
An overview of the system hardware is also provided
Direct Drive LCD Overview
The H8S and H8SX device families include several peripherals that enable the direct connection of RGB
interface TFT panels directly to the MCU data bus. These peripherals include the ExDMA (external DMA
controller unit) and the TPU (Timer Pulse Unit). With these peripherals and an external RAM device (for
LCD frame buffer use), the LCD panel can be refreshed using less than 5% of the MCU processing
capacity.
1.1.1 Philosophy
The Direct Drive LCD solution was developed to provide a low cost, long life solution for driving TFT
panels for use in GUI applications with limited animation requirements. This solution reduces the risk for
products with relatively long life on volatile components (such as stand alone LCD controllers, TFT panels
with integrated LCD controllers, or application specific microprocessors).
1.1.2 Capabilities
The current features of the Direct Drive LCD solution are:
• Ability to use standard PSRAM, SRAM or SDRAM as frame buffer.
• Ability to create multiple frame buffers within the available RAM.
• Ability to dynamically modify frame rate to accommodate varying system update requirements.
• Ability to drive RGB panels at 16bpp up to WVGA resolution at up to 60Hz frame rates.
• Ability to pan larger display regions within a portion of the LCD panel area.
• Very simple operation model…user code manipulates images in the frame buffer. The frame buffer
is transparently transferred to the LCD panel.
The Direct Drive LCD solution is highly configurable, and capable of producing many different timing
configurations which drive the input signals of TFT-LCD panels from various panel manufacturers. The
signal timing generated from the Direct Drive LCD solution depends on your choice panel resolution,
frame buffer memory, and desired panel refresh and animation rates.
Although Renesas provides guidelines and examples for configuring the signal timing, Renesas is not
responsible for meeting the AC timing specifications of your specific choice of TFT-LCD panel. Please
contact your TFT-LCD panel manufacturer to ensure the Direct Drive LCD solution complies with the
panel timing limitations.
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