Abstract:
The purpose of the research was to develop a Display Panel using LED's (Light Emitting
Diodes)in order to display text messages and special graphical characters including English
and Sinhalese language characters (virtually any language) with the facility to upload the
devicewith data using USB (Universal Serial Bus) interface.
Thewell known micro-controller PIC18F4550 by Microchip@Technology Inc. was used as
the heartof the device with the assistance of mikroC language by Mikroelektronika@ for the
PICmicro-controllerprogramming at the device end. Microsoft@Visual Basic@ 6.0 language
wasusedfor interface programming at the user end.
Theinterfacingsoftware can decode any text written in a textbox using a particular font face
anduploadthe device with data using USB interface, only when the authentic user is present
withthe preprogrammed password. After uploading, the data is permanently resided on the
devicememoryand the device then can start displaying the message on 640-LED (16 by 40)
panel. After uploading the data, the device can be disconnected immediately. Since the
displaydevice is hot pluggable, the interfacing software would automatically detect it upon
deviceconnect/disconnect.The data on the permanent memory can be modified anytime very
quicklyby connecting it to a PC (Personal Computer). The device can display messages in
any language (provided the font face is available) with variable speeds (7 programmable
displayspeeds) and with different modes of display such as move left, move right, move up,
movedownand flip down. Moreover, an online mode has also been embedded in order to use
the deviceas a clock/calendar. In this mode, the device would display current date and time
butthe device has to be connected to the PC since the calendar information is' extracted from
therealtime clock of the PC. The maximum display size currently is 700 vertical lines which
is approximatelyequivalent to 90 characters. If needed, the size of the display panel can be
extendedwith extra decoder/driver logic easily.
