083730300A DCN8101 Theory of Operation 165
6.4.8 FRONT PANEL TOUCHSCREEN/DISPLAY INTERFACE
Users can input data and receive information directly through the front panel touchscreen
display. The LCD display is controlled directly by the CPU board. The touchscreen is
interfaced to the CPU by means of a touchscreen controller that connects to the CPU via
the internal USB bus and emulates a computer mouse.
Figure 6-17. Front Panel and Display Interface Block Diagram
6.4.8.1 LVDS TRANSMITTER BOARD
The LVDS (low voltage differential signaling) transmitter board converts the parallel
display bus to a serialized, low voltage, differential signal bus in order to transmit the
video signal to the LCD interface PCA. (Note that the signals are not HDMI compatible).
6.4.8.2 FRONT PANEL TOUCHSCREEN/DISPLAY INTERFACE PCA
The front panel touchscreen/display interface PCA controls the various functions of the
display and touchscreen. For driving the display it provides connection between the CPU
video controller and the LCD display module. This PCA also contains:
• power supply circuitry for the LCD display module
• a USB hub that is used for communications with the touchscreen controller and the two front
panel USB device ports
• the circuitry for powering the display backlight
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