static void doGbr (int argc, char *argv [])
{
int channel ;
if (argc != 3)
{
fprintf (stderr, "Usage: %s gbr <channel>\n", argv [0]) ;
exit (1) ;
}
channel = atoi (argv [2]) ;
if ((channel < 0) || (channel > 1))
{
fprintf (stderr, "%s: channel must be 0 or 1\n", argv [0]) ;
exit (1) ;
}
if (gertboardSPISetup () == -1)
{
fprintf (stderr, "Unable to initialise the Gertboard SPI interface: %s\n", strerror (errno)) ;
exit (1) ;
}
printf ("%d\n",gertboardAnalogRead (channel)) ;
}
static void sample (void)
{
unsigned int tFuture ;
// Calculate the future sample time
tFuture = tPeriod + tNextSampleTime ;
// Wait until the next sample time
while (micros () < tNextSampleTime)
;
buffer [bPtr] = gertboardAnalogRead (0) ;
tNextSampleTime = tFuture ;
}