User manual
Display Expansion Board - User’s Guide
Page 7
Copyright 2012 © Embedded Artists AB
3 Getting Started
This chapter describes important aspects of using the Display Expansion Board.
3.1 Selecting Video Resolution
It is recommended to prototype with a display/monitor/tv that has identical resolution as the intended
end-application. If the exact same resolution cannot be used during prototyping, select a resolution as
close to the end-application as possible. The reason for this is that different display resolutions give
different application program load (program execution time) and different load on the external memory
bus, where the frame buffer typically resides. When developing real-time systems, which many
embedded system are, it is advised to not alter fundamental things, like system load.
Note that size of the display/monitor/tv is of no importance for the discussion above. It is the resolution
that gives a certain load on the application and external memory bus. Size can of course also be
important when evaluating the usability and interaction with the user.
The Display Expansion Board supports at least four different standard resolutions and can easily be
extended to support more:
VGA, 640x480 pixels, 25.175MHz pixel clock. 60Hz frame frequency.
SVGA, 800x600 pixels, 36MHz pixel clock. 56Hz frame frequency.
480p, 720x480 pixels, 27.027MHz pixel clock. 60Hz frame frequency.
27.000MHz pixel clock is used instead of 27.027MHz.
576p, 720x576 pixels, 27MHz pixel clock. 50 Hz frame frequency.
The Display Expansion Board, support primarily 16- and 12-bit color depth because when increasing
the color depth above 16-bits, the memory requirements and external bus load will double. This is at
least true for NXP’s LPC-family of processors with integrated LCD controller. Instead of having 2 bytes
per pixel (for 16- and 12-bit color depth) 4 bytes are needed per pixel.
3.2 Mounting
The Display Expansion Board can optionally be mounted with the OEM Base Board. The board is
mounted the same way as other LCD boards. The product and support page both contains a link to a
short video demonstrating how to mount the LCD Board together with the OEM Base Board. Before
mounting, watch the instruction video. The Display Expansion Board is mounted the same way as
the LCD Board. A Phillips screw driver #1 and a small adjustable spanner are needed to complete the
mounting.
Note that it is not strictly needed to mount the Display Expansion Board together with the OEM Base
Board. It is just practical. It is also possible to have the board beside the OEM Base Board. Figure 1
below illustrates how it looks like when the two boards are mounted together.