2-23
●
Software-triggered strobe (Mode 4) - The output is initially high.
Writing the initial count through software loads the initial count value
into the counter at the next clock pulse, but the counter does not start
counting. At the next clock pulse, the counter starts counting down.
When the counter reaches zero, the output goes low for one clock
pulse and then goes high again. Note that the output does not go low
until n + 1 clock pulses after the initial count is written, where n
indicates the loaded count.
A high gate input enables counting; a low gate input disables
counting. The gate input has no effect on the output.
Figure 2-10 illustrates software-triggered strobe mode.
Figure 2-10. Software-Triggered Strobe Mode
Clock pulse
Output
Software loads counter
with initial count
Software writes initial
count value of 3
3
2
1
