Datasheet

 2011 Microchip Technology Inc. DS01368A-page 11
AN1368
FIGURE 11: MEASUREMENT OF THE X-VOLTAGE
FIGURE 12: MEASUREMENT OF THE Y-VOLTAGE
DECISION FACTORS
After understanding the basic definitions and
components of a graphics subsystem, the next step is
to decide the specifications for the application. Some of
the important factors that needs to be considered when
deciding on specifications are as follows:
• Display Resolution and Size
• Display Orientation – Portrait or Landscape
• Color Depth (BPP)
• Frame Buffer Size
• Microcontroller Processing Power
• Configuration of Graphics Components
• Frame Rate vs. MIPS
• Interfacing with Unmatched Number of Display
RGB Lines
These decision factors are described in the following
sections.
Display Resolution and Size
A particular resolution can be obtained in different
display sizes. For example, QVGA (320x240) displays
are available in a size range of 1.5'' to 5.7''. As the size
increases, keeping the resolution constant, the pixels
will look coarser, that is, curved shapes on the screen
will appear blocky.
In an application, if the user needs to look at the display
from a short distance (e.g., hand held devices), higher
resolution displays are a better choice for larger
displays. If the user looks at the display from a long dis-
tance (e.g., token number of displays at banks), larger
sized displays with lower resolution may be used. If
pictures are being displayed, it is better to use a higher
resolution. Figure 13 illustrates how ‘A’ appears on a
smaller sized lower resolution display, larger sized lower
resolution display and larger sized higher resolution
display, respectively.
FIGURE 13: DISPLAY OF ‘A’ AT
VARIOUS RESOLUTIONS
PIC
®
MCU
Digital I/O
Digital I/O
Dig-O/AN-I
Dig-O/AN-I
1
0
X
Y
X
Y
Sense
with ADC
PIC
®
MCU
Digital I/O
Digital I/O
Dig-O/AN-I
Dig-O/AN-I
1
0X
Y
X
Y
Sense
with ADC