Figure c-1. firmware recovery operation, Vxibus clk10 routing – National Instruments VXI-USB User Manual
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Appendix C
Advanced Hardware Configuration Settings
C-2
ni.com
Figure C-1. Firmware Recovery Operation
VXIbus CLK10 Routing
The VXI-USB has four hardware switches that work together to control
various aspects of CLK10 routing. Read this section carefully and notice
that if you change one switch, you may need to change another. This section
includes several diagrams that show how to configure the four switches to
accomplish various CLK10 configurations.
Notice that the configuration of one switch may make the setting of another
switch irrelevant. The drawings use the
pattern to depict switches that
are either irrelevant or disabled for a particular CLK10 configuration.
Switch S3 uses this pattern in all of the CLK10 drawings. It deals with the
external trigger input SMB and is discussed later in this appendix.
The VXI-USB can use two different sources to generate the VXIbus
CLK10 signal—an onboard oscillator or the external CLK SMB connector.
Use switch S2 to select between these options. The VXI-USB uses the
onboard oscillator by default.
The VXI-USB can also be configured to drive the external CLK SMB from
the VXIbus CLK10 signal. Switch S5 controls whether the VXI-USB
drives or receives the external CLK SMB. If you change the S5 setting to
drive CLK10 out the external CLK10 SMB connector, do not set switch S2
to receive the SMB CLK10 signal. Instead, use its default setting so that the
onboard oscillator generates the signal.
You can use an additional switch, S6, to control the polarity of the external
CLK SMB signal when S5 is configured to drive it. S6 is unused when S5
is configured to receive the external CLK SMB signal.
A. Boot from Onboard EEPROM
and Flash Memory (Default)
B. Boot from Firmware
Image Stored on Host
S1
Y
N
Y
N
S1