Echelon I/O Model Reference for Smart Transceivers and Neuron Chips - Manual (Page 143)

I/O Model Reference 133
io-object-name
A user-specified name for the I/O object, in the ANSI C format for variable
identifiers.
In Figure 50, an io_in( ) function call is executed sometime after the IO_4 input
signal is sensed as changing to high, but before it has changed back to low. The
first period, Period [1], is stored as a value in the array pointed to by the buffer
argument. If the io_in( ) function call occurs within the Period [2] time frame,
the data for Period [1] is lost.
Individual period measurements can be skipped if the sum of two consecutive
periods is less than 104 μs (for a Series 3100 device with a 10 MHz input clock),
regardless of the timer/counter clock setting. The minimum value scales with the
input clock.
Figure 50. Call to io_in(device, buffer, count)
If the IO_4 input pin has been at a constant level for longer than the overflow
period before the call to io_in( ) is made, the first value stored in the buffer is not
the maximum value, but rather the value for the next period.
Usage
unsigned int count ;
unsigned long input-buffer [ buffer-size ];
count = io_in( io-object-name , input-buffer , count );
Example
IO_4 input edgelog clock(7) ioTimeStream;
// The next object allows direct reading
// of time_stream level.
IO_4 input bit ioTimeStreamLevel;
unsigned int edges;
unsigned long buffer[20];
unsigned long preLoad = 0x4000;
when (reset) {
io_edgelog_preload(preLoad);
}
when (io_changes(ioTimeStreamLevel) to 1) {
int i;