National Instruments AT-MIO-16X Programming

National Instruments Corporation 5-1 AT-MIO-16X User Manual

Chapter

Programming

This chapter contains programming instructions for operating the

circuitry on the AT-MIO-16X.

Programming the AT-MIO-16X involves writing to and reading from

the various registers on the board. The programming instructions list th e

sequence of steps to take. The instructions are language independent;

that is, they instruct you to write a value to a given register, to set or

clear a bit in a given register, or to detect whether a given bit is set or

cleared without presenting the actual code.

Note: If you plan to use a programming software package such as NI-DAQ

or LabWindows/CVI with your AT-MIO-16X board, you need not read this

chapter.

Several write-only registers on the AT-MIO-16X contain bits that

control a number of independent pieces of the onboard circuitry. In the

instructions for setting or clearing bits, specific register bits should be

set or cleared without changing the current state of the remaining bits in

the register. However, writing to these registers simultaneously affects

all register bits. You cannot read these registers to determine which bits

have been set or cleared in the past; therefore, you should maintain a

software copy of the write-only registers. This software copy can then

be read to determine the status of the write-only registers. To change the

state of a single bit without disturbing the remaining bits, set or clear

the bit in the software copy and write the software copy to the register.

Counters 1, 2, and 5 of the Am9513A Counter/Timer are available at the

I/O connector for general-purpos e use . Thes e coun ters c an on ly be used

so long as this does not conflict with an internal operation in progress

on the board that is already using the desired counter. Table 5-1 lists the

five counters in the Am9513A Counter/Timer and enumerates wh at

they are used for in each operation.