Agilent Technologies 16900A, Service Manual

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Theory of Operation
8
16900A, 16902A, and 16903A Service Guide 125
In addition to the PCI bridge chip providing a secondary PCI
bus, this PCI board is used to route the touch screen RS232
COM2 connection. Routing of this function through the PCI
board is for mechanical purposes. Attached to the front
panel interface board is a Touch Screen Control module used
to implement the touch screen. This control module uses 15
V RS232 to communicate with the CPU motherboard. The
two wire RS232 signals are routed from the Front Panel
Interface board, through the Module Interface Board, and
then finally to this PCI board. The ten pin connector J2 is
used to connect the two- wire RS232 interface to the COM2
connector on the CPU motherboard.
16903A MIB (Module Interface Board)
Top level function
The MIB contains all of the logic analyzer frame specific
hardware. This includes all circuits necessary to interface
with measurement modules, drive the front panel assembly,
monitor frame functions and interface to the CPU
motherboard via a PCI port. It also performs power
distribution and numerous interconnects.
Module bus FPGA
The Xilinx XC2S400E FPGA is the primary bridge between
the CPU and the measurement modules. It effectively
performs a translation from PCI slot to the proprietary
module interface bus. This bus includes three module slots
plus the I/O FPGA.
Video circuit
The video circuit components include a flat panel display
controller IC, boot ROM, and display RAM. The controller IC
interfaces to the CPU via a PCI port from the PCI board.
The display mode used is 800x600 pixels, 12 bit color, with a
LVTTL interface to the display assembly.
I/O FPGA
The Xilinx XC2V250 FPGA is the center of the instrument
I/O functions. The system interfaces directly to this part in
the same way it talks to the three module slots, via a 16- bit
multiplexed general purpose bus. The FPGA is loaded from