Matrix Orbital GTT70A - Manual (Page 6)

Command Summary 2
1.2 Basic Features
Drawing
The most basic commands available for the GTT line are the drawing features. Simple shapes, from
pixels to triangles, can easily be drawn on the unit using a number of available commands. It should be
noted that the coordinate system of the GTT references the top left pixel as 0,0 and increments
positively to the right and down, as shown below.
Figure 1: Pixel coordinate orientation (GTT43A shown)
The drawing colour can be set globally by specifying values for red, green, and blue channels, and will
default to white. The Get Display Metrics function will report the number of bits available for each
colour channel. The GTT will use the highest bits of any colour specified, dropping the lowest if
necessary. For example, if the display uses 5 bits for red, setting the drawing colour to any value
between 0 and 7 will result in the same, black, colour.
In addition to basic drawing commands, the GTT offers a number of more advanced features that enable
complex graphical environments to be created with ease.
Graphs
Graphs simplify the visual display of numerical information on the screen by taking care of the
calculations and placement of graphics. Once a graph is created, only the new value needs to be sent to
update it. The ratio of the new value to the minimum and maximum levels is automatically calculated,
and the graphic is updated. 9-Slice graphs also allow for complex graphics to be used for more detailed
rendering. Graph information is stored in a series of graph locations. A unique index is specified when a
graph is created, and used to reference the graph in future commands.
1.3 Mass Storage
When powered with a jumper on the ”A” side of the mass storage jumper, the unit will appear to any PC
as a mass storage device when connected via the Mass Storage USB header. The onboard SD memory
card is used to store all user fonts, bitmaps, 9-slices, animations and start-up settings.
At run time, files can be loaded from the mass storage SD card into specific memory buffers for use as
outlined below. Each font, bitmap, 9-slice, animation, label, and trace buffer has 256 unique index slots
available, and up to 32MB of data can be stored across all buffers at any one time.