Agilent Technologies 8564EC, Service Manual

Page: 495 / 512

636 Chapter 13
Display/Power Supply Section
LCD Display
Figure 13-1 Simplified LCD Block Diagram
Overview of A17 Display Driver Board
The A17 display driver board monitors the 8560 EC-series controller
board, copies display instructions to local memory, creates a bitmap
from the data, and generates the signals needed to drive the LCD
display and a VGA monitor. The display driver consists of a Hitatchi
7707 processor, an FPGA, DRAM, SRAM, a filter circuit, and a video
DAC.
The FPGA is connected to the address bus, data bus, and the display
memory control signals on the controller board. The FPGA monitors the
control signals and determines when the Hitatchi 7707 processor writes
to display memory. When this occurs, the FPGA makes a duplicate of
this information on the display driver board. The other main function of
the FPGA is to provide the signals necessary to drive a TFT LCD
display and a standard VGA monitor.
The processor reads display information received from the controller
board, creates a bitmap, and copies the bitmap into SRAM. The FPGA
outputs this information to the LCD and VGA displays. The DRAM is
used by the processor to run its program. The filter circuit provides the
clock signals that are needed to run the display driver board. The video
DAC converts the digital color information that goes to the LCD to
analog signals; these signals drive the RGB color lines on the VGA port.