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<H2><A NAME="SECTION00521000000000000000">
The A/D Driver</A>
</H2>
The most basic device driver for an A/D board should contain, as a
minimum, the following template:
<P>
<PRE>
#include ``main.h'' /* needed */
int RTiC_init_AD_card(void)
{
/* do all card initialization here */
return(RTIC_SUCCESS); /* or RTIC_ERROR, depending */
}
void RTiC_AD1_run(void)
{
/* do all periodic jobs here */
}
void RTiC_AD2_run(void)
{
/* do all periodic jobs here */
}
int RTiC_stop_AD_card(void)
{
/* do all card ``stopping'' functions here */
return(RTIC_SUCCESS); /* or RTIC_ERROR, depending */
}
</PRE>
<P>
The first function <TT>RTiC_init_AD_card</TT> is run immediately after
the user releases the ``RUN'' button in <TT>xrtic</TT>. Similarly, the
last function, <TT>RTiC_stop_AD_card</TT> is run immediately after the
user releases the ``STOP'' button in <TT>xrtic</TT>. In both of these
cases, the functions must return either ``RTIC_ERROR'' or
``RTIC_SUCCESS'', depending on whether an error was encountered or
not, respectively.
<P>
The <TT>RTiC_AD1_run</TT> and <TT>RTiC_AD2_run</TT> functions, on the
other hand, have a completely different use. These functions are
called once per controller cycle. The first function, <TT>RTiC_AD1_run</TT> is used to trigger A/D conversions in the A/D
cards. Then, sometime later, and prior to the execution of the user's
controller, the function <TT>RTiC_AD2_run</TT> will be called, at which
time this function should load the data vector pointer (<TT>float
*RTiC_sensor</TT>) with the sampled data, for example:
<P><PRE>
for (i=0; i<NUM_CONTROL_INPUTS; i++)
*(RTiC_sensor+i) = INW(AD_BASE);
</PRE>
<P>
<BR><HR>
<ADDRESS>
Michael Barabanov
2001-06-19
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