Specifications

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3.5.2 Touch Interface
The touch controller of the SLCD5 is meant to interface to a four wire resistive
touchscreen. Touch sensitive areas on the display are defined as either
“hotspots” or “buttons”. When either of these is pressed or released, the SLCD5
has the ability to either notify the host directly or execute a “macro” which is a
predetermined sequence of SLCD5 commands.
A hotspot is an area of the display that is touch-sensitive. The two types of
hotspots are visible and invisible hotspots. A visible hotspot is the standard type
of hotspot and when it is touched, the display area of the hotspot is color inverted
in order to provide a visual indication that a hotspot has been activated. On the
other hand, an invisible hotspot does not provide any visual indication when it
has been touched. When a touch control is used to switch display screens, an
invisible hotspot is the best option because the host redraws the screen when the
hotspot is pressed and sometimes the hotspot area can become inverted when
the user removes their finger from the screen.
A button is the other type of touch sensitive area on the display is a button. A
button is a touch sensitive area with two bitmaps associated with it. These
bitmaps correspond to the two states of the button (normal/not pressed and
active/pressed). This allows the button to take on the form of any GUI object
including pushbuttons, toggle switches, radio buttons, check boxes, and so forth.
There are normal (momentary) and latching buttons. A momentary button only
changes its visual state when pressed (such as a keyboard key) while a latching
button is like a checkbox where the button is pressed and released and the
checkbox is filled and another press and release is required to clear the box.
3.5.3 Bitmap Images and the BMPload
Program
Many areas on the touch screen, whether touchable or not touchable are actually
bitmap images that must be loaded onto the controller from a computer.
Examples of bitmaps that will be loaded onto the screen via the controller are
logos, all buttons, or any pictures that the sponsor specifies must be on the LCD
display. The SLCD5 has 4 Megabytes of on-board data flash memory for storing
bitmaps and macros. Since bitmaps are used to create most of the visual
elements of the user interface, the programmer may find the need to create
certain bitmap images to be loaded onto the controller board. Some popular
programs used to create bitmaps are Adobe Photoshop, and the open source
program, GIMP. The programmer can simply use the “PrintScreen” function of
the PC to capture the desired element and then paste the screen to either
Photoshop or GIMP. Bitmaps must be saved in 24 bit RGB color mode.
In order to load a bitmap image onto the controller, it must be hooked up to a
computer that is running the BMPload program (.bmp is the Windows file
extension for a bitmap file. The BMPload program is included with the
development kit we have purchased. The BMPload program requires bitmaps to