Chapter 9

Counters

Counter Output Applications

Simple Pulse Generation

Single Pulse Generation

The counter can output a single pulse. The pulse appears on the Counter n

Internal Output signal of the counter.

You can specify a delay from when the counter is armed to the beginning of the pulse. The delay is measured in terms of a number of active edges of the Source input.

You can specify a pulse width. The pulse width is also measured in terms of a number of active edges of the Source input. You also can specify the active edge of the Source input (rising or falling).

Figure 9-22shows a generation of a pulse with a pulse delay of four and a pulse width of three (using the rising edge of Source).

Counter Armed

SOURCE

OUT

Figure 9-22.Single Pulse Generation

Single Pulse Generation with Start Trigger

The counter can output a single pulse in response to one pulse on a hardware Start Trigger signal. The pulse appears on the Counter n Internal Output signal of the counter.

You can route the Start Trigger signal to the Gate input of the counter. You can specify a delay from the Start Trigger to the beginning of the pulse. You also can specify the pulse width. The delay and pulse width are measured in terms of a number of active edges of the Source input.

After the Start Trigger signal pulses once, the counter ignores the Gate input.