ICS Advent ADIO1600 Series, Руководство по эксплуатации продукта, Страница: 54 / 72

Manual Number: 00650-004-5 Page 7-6
ADIO1600 Manual
Generating Time Delays
There are four methods of using Counter #0 to generate programmable time delays.
Pulse on Terminal Count
After loading, the counter output goes low. Counting is enabled when the gate goes high. The
counter output will remain low until the count reaches zero, at which time the counter output goes
high. The output will remain high until the counter is reloaded by a programmed command. If the
gate goes low during countdown, counting will be disabled as long as the gate input is low.
Programmable One-Shot
The counter need only be loaded once. The time delay is initiated when the gate input goes high. At
this point the counter output goes low. If the gate input goes low, counting continues but a new cycle
will be initiated if the gate input goes high again before the timeout delay has expired; i.e., is
re-triggerable. At the end of the timeout, the counter reaches zero and the counter output goes high.
That output will remain high until re-triggered by the gate input.
Software Triggered Strobe
This is similar to Pulse-on-Terminal-Count except that, after loading, the output goes high and only
goes low for one clock period upon timeout. Thus, a negative strobe pulse is generated a pro-
grammed duration after the counter is loaded.
Hardware Triggered Strobe
This is similar to Programmable-One-Shot except that when the counter is triggered by the gate
going high, the counter output immediately goes high, then goes low for one clock period at timeout,
producing a negative-going strobe pulse. The timeout is re-triggerable; i.e., a new cycle will com-
mence if the gate goes high before a current cycle has timed out.
Generating Interrupts With the Counter/Timer
The ADIO1600 architecture allows you to directly generate an interrupt upon an ADC end of con-
version or the timeout of Counter #2. This allows you to either read the converted data or use the
counter while using external start of conversions.
Note: Also that it is possible to trigger the A/D externally or by a programmed write to an I/O port
and invoke an interrupt at the end of A/D conversion in the same way.