•If C/T = 1 (in TMOD), counter
operation is selected and timer is clocked from external
source. Usually, external source supplies the timer with a pulse upon the
occurrence of an event. Timer counts those events.
clock source comes through P3.4 (for Timer 0) and P3.5 (for Timer
registers are incremented in response to a 1-to-0 transition at the
of external events is determined in software by reading the timer