Chapter 5 Programming
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National Instruments Corporation 5-37 AT-MIO-16X User Manual
If any digital I/O line is not driven, it floats to an indeterminate value.
If more than one device is driving any digital I/O line, the voltage at that
line may also be indeterminate. In these cases, the digital line has no
meaningful logic value, and reading the Digital Input Regi ster ma y
return either 1 or 0 for the state o f th e digi ta l li ne .
Programming the Am9513A Counter/Timer
Counters 1, 2, and 5 of the Am9513A Counter/Timer are available for
general-purpose timing applications. The programmable frequency
output pin FOUT is also available as a timing signal source. These
applications and a general description of the Am9513A Counter/Timer
are included in the Timing Connections for Data Acquisition and
Analog Output section in Chapter 2, Configuration and Installation.
The Timing I/O Circuitry section in Chapter 3, Theory of Operation ,
explains how the Am9513A is used on the AT-MIO-16X boa rd.
Initialization of the Am9513A as required by the AT-MIO-16X and
specific programming requirements for the sample-inter val an d samp le
counters are given earlier in this chapter. For general programming
details for Counters 1, 2 and 5, and the programmable frequency output,
refer to Appendix C, AMD Am9513A Data Sheet .
In programming the Master Mode Register, keep the following
considerations in mind:
• The Am9513A must be used in 16-bit bus mode.
• The scaler control shou ld be set to BC D division f or corr ect
operation of the clocks as shown in Figure 5-1.
RTSI Bus Trigger Line Programming Considerations
The RTSI switch connects signals on the AT-MIO-16X to the seven
RTSI bus trigger lines. The RTSI switch has seven pins labeled A<6..0>
connected to AT-MIO-16X signals and seven pins labe led B<6. .0>
connected to the seven RTSI bus trigger lines. Table 5-2 shows the
signals connected to each pin.