82C54
After writing the Control Word and initial count, the
counter will not be loaded until the CLK pulse after a
trigger. This CLK pulse does not decrement the
count, so for an initial count of N, OUT does not
strobe low until N
a
1 CLK pulses after a trigger.
A trigger results in the Counter being loaded with the
initial count on the next CLK pulse. The counting
sequence is retriggerable. OUT will not strobe low
for N
a
1 CLK pulses after any trigger. GATE has
no effect on OUT.
If a new count is written during counting, the current
counting sequence will not be affected. If a trigger
occurs after the new count is written but before the
current count expires, the Counter will be loaded
with the new count on the next CLK pulse and
counting will continue from there.
231244–13
Figure 20. Mode 5
Signal Low
Status Or Going Rising High
Modes Low
0 Disables Ð Enables
counting counting
1 Ð 1) Initiates Ð
counting
2) Resets output
after next
clock
2 1) Disables
counting Initiates Enables
2) Sets output counting counting
immediately
high
3 1) Disables
counting Initiates Enables
2) Sets output counting counting
immediately
high
4 Disables Ð Enables
counting counting
5 Ð Initiates Ð
counting
Figure 21. Gate Pin Operations Summary
MODE
MIN MAX
COUNT COUNT
01 0
11 0
22 0
32 0
41 0
NOTE:
0 is equivalent to 2
16
for binary counting and 10
4
for
BCD counting
Figure 22. Minimum and Maximum initial Counts
13
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