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Chapter 4
Theory of Operation
©
National Instruments Corporation
4-9
Timing I/O Circuitry
The DAQCard-700 uses an MSM82C54 counter/timer integrated circuit
for DAQ timing and general-purpose TIO functions. Three counters of
the MSM82C54 are available for general use, but Counter 0 is also used
internally for DAQ timing. Figure 4-5 shows a block diagram of both
groups of TIO circuitry.
Figure 4-5.
Timing I/O Circuitry Block Diagram
PCMCIA
I/O
Channel
I/O
Connector
OUT0
GATE0
CLK0
CLK1
GATE1
OUT1
CLK2
GATE2
OUT2
CTR RD/WR
Input
Mux
1-MHz
Clock
A/D Conversion Logic
Interrupt
Interface
MSM82C54 Counter/Timer
8
Data
CLK1
OUT1
OUT1*
CLK2
GATE2
OUT2
OUT0
GATE0