Specifications

Counter/Timers
The TCTL signal is used to enable and disable the counting operation.
The counting operation is enabled if TCTL is high and disabled if
TCTL is low. TCTL has no effect on the TOUT signal.
The Down Counter does not begin decrementing until the clock pulse
after the count is programmed. This is because it takes one clock
pulse to transfer the count from the Count register to the Down
Counter. This means that for an initial count of N, TOUT does not
transition high until N + 1 clock pulses later.
If a new count is written to the counter/timer before the previous
count is decremented to zero, the Down Counter begins counting from
the new count after the next clock pulse. If the count is two bytes
long, the first byte disables counting and lowers TOUT. Not until one
clock pulse after the second byte is programmed will the entire count
be transferred to the Down Counter.
It is possible to start the Down Counter with the TCTL signal by
programming the initial count with TCTL low. The programmed
count will be transferred to from the Count register to the Down
Counter on the next clock pulse. TOUT will not go low until N clock
pulses after TCTL goes high.
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