Matrix Orbital GLK24064-25 Legacy - Manual (Page 14)

GLK24064-25 rev. 06 14
4. Displaying Graphics
This chapter describes the various graphics-display commands in detail. A quick reference summary of all
graphics commands is found in section 8.5.
4.1 General
Since the GLK24064-25 is a bit mapped device, it may be used to display graphics. Graphic images may be
created by means of a pixel-oriented graphics program, saved as bitmaps, and loaded into the GLK24064-
25 using the mogd.exe program. Images may be saved in the GLK24064-25's memory, and displayed upon
command, or they may be downloaded "on the fly" (inline) during GLK24064-25 operation.
Note that "saved" and "on the fly" graphics images are processed differently. These differences must be
taken into account when processing graphics.
Saved bitmaps use each byte (8 bits) to represent a vertical column of 8 pixels. The next byte represents the
next column to the right If the graphic is "taller" than 8 pixels, the LSB of the next data byte will be the next
pixel. Orientation is top to bottom – LSB to MSB. Pixels/bits are “packed” – that is, if the height of the
graphic is not an even multiple of 8, the leftover bits go on the next X column to the right), etc. (see the
figure below).
Inline bitmaps are processed horizontally, and each byte represents a horizontal row of 8 bits, with the next
byte representing the next 8 bits to the right Orientation is left to right – MSB to LSB, which is the opposite
to the serial transmission sequence (bytes are sent LSB first).
Saved Bitmap
Byte 2
Byte 1 Byte 3
Byte 4
Byte 5
lsb
msb
lsb
msb
lsb
msb
lsb
msb
lsb
lsb
msb
lsb
msb
lsb
msb
msb
lsb
msb
Byte 1
Byte 2
Byte 3
Byte 3
Byte 4
16 pixels high 20 pixels high
Inline Bitmap
16 pixels wide
Byte 1 Byte 2
Byte 3 Byte 4
msb lsb msb lsb
msb lsb lsb msb
Note: inline bitmaps must
be a multiple of 8 pixels
wide.
Figure 4-1 Graphic bitmaps
Each pixel in a bitmap is described by a single bit, and may only have the values ON or OFF, i.e. shades of
gray are not supported.
4.2 Graphics Commands
In this section commands are identified by their names and decimal values. Hex and ASCII equivalents are
given in the summary (Table 8-2). Before issuing commands to the GLK24064-25 please read sections
8.2 and 8.3.