LCD Display Controller

3

This chapter describes sample hardware connections from the PXA250 applications processor to various types of LCD controllers. Active (TFT) as well as passive (DSTN) displays are discussed as well as single and dual panel displays. These should not be considered the only possible ways to connect an LCD panel to the PXA250 applications processor, but should serve as a reference to assist with hardware design considerations. Other panels, for example panels without L_FCLK or L_LCLK, have been successfully connected to the PXA250.

3.1LCD Display Overview

The PXA250 applications processor supports both active and passive LCD displays. Active displays generally produce better looking images, but at a higher cost. Passive displays are generally less expensive, but their displays are inferior to active displays. However, recent advances in dithering technology are closing the quality gap between passive and active displays.

Note: Names used for “LCD Panel Pin” are representative names and may not match those on all LCD panels. Refer to the LCD panel reference documentation for the actual name.

3.2Passive (DSTN) Displays

Several different types of passive displays are available in both color and monochrome. These maybe single or dual panel displays. Additionally, some monochrome displays use double-pixel data mode (twice the number of pixels as a normal monochrome display). With the exception of the number of data pins required, all of these choices affect the software configuration and support, not the system hardware design. In fact, most passive displays use a single interconnection scheme. For information on the software changes and performance considerations of the various display options, refer to the PXA250 and PXA210 Applications Processors Developer’s Manual.

Passive displays drive dithered data to the LCD panel - which means that for each pixel clock cycle a single data line drives an ON/OFF signal for one color of a single pixel.

Table 3-1describes the number of L_DD pins required for the various types of passive displays, as well as which LCD data pins are used for which panel (upper or lower).

Table 3-1. LCD Controller Data Pin Utilization (Sheet 1 of 2)

Color/

Single/

Double-Pixel

 

 

Monochrome

Screen Portion

Pins

Dual Panel

Mode

Panel

 

 

 

 

 

 

 

 

 

 

 

Monochrome

Single

No

Whole

L_DD<3:0>

 

 

 

 

 

Monochrome

Single

Yes

Whole

L_DD<7:0>1

Monochrome

Dual

No

Top

L_DD<3:0>

 

 

Bottom

L_DD<7:4>

 

 

 

 

 

 

 

 

Color

Single

N/A

Whole

L_DD<7:0>

 

 

 

 

 

PXA250 and PXA210 Applications Processor Design Guide

3-1

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Intel PXA250 and PXA210 manual LCD Display Controller, LCD Display Overview, Passive Dstn Displays

PXA250 and PXA210 specifications

The Intel PXA250 and PXA210 processors, part of the Intel XScale architecture, were introduced in the early 2000s, targeting mobile and embedded applications. They are known for their low power consumption, high performance, and advanced multimedia capabilities, making them suitable for a wide range of devices, including PDAs, smartphones, and other portable computing devices.

The PXA250, which operates at clock speeds ranging from 400 MHz to 624 MHz, features a superscalar architecture that allows it to issue multiple instructions per clock cycle. This enhances the overall performance for demanding applications while maintaining low power usage. It supports a variety of peripheral interfaces, including USB, Ethernet, and various memory types, which contributes to its versatility in different product designs.

One of the key technologies in the PXA250 is the integrated Intel Smart Repeat Technology, which optimizes data processing, thereby reducing the amount of power consumed during operation. This feature is particularly important for battery-powered devices, as it extends the overall battery life, allowing for longer usage times in mobile environments. Additionally, the PXA250 includes a dedicated graphics acceleration unit, which enables enhanced graphics and multimedia performance suited to modern applications at the time.

In contrast, the PXA210 is a more entry-level processor, aimed at cost-sensitive applications. Operating at lower clock speeds, typically around 200 MHz to 400 MHz, it forgoes some of the advanced performance features of the PXA250 while still offering a good balance of performance and power efficiency. The PXA210 is less complex, making it suitable for simpler devices that do not require the extensive capabilities of the PXA250.

Both processors utilize the Intel XScale architecture, which is based on the ARM instruction set. They are built on a 0.13-micron process technology, enabling higher density and lower power consumption compared to their predecessors. With integrated memory controllers and bus interfaces, they facilitate efficient data handling and connectivity options.

In summary, both the Intel PXA250 and PXA210 processors played a crucial role in the evolution of mobile computing by providing powerful processing capabilities with energy efficiency. Their features and technologies enabled device manufacturers to create innovative products that catered to the growing demand for portable devices during that era.