Samsung S5PC110, Manual

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S5PC110_UM 2 SYSTEM TIMER
2.4 DETAILED OPERATION
Figure 2-3 Timer Operation with Always on of Auto-reload
Usually, the tick interval is fixed after initial setting and you can change the interrupt interval at run-time.
Figure 2-3
shows the detailed operation of interrupt counter (INTCNT) and interrupt counter observation SFR (ICNTO) with
auto-reload. Each rectangular block shows one tick time. Although the interrupt interval is changed, one tick time
is fixed because tick and interrupt counter are independent of each other.
Interrupt is asserted when INTCNT value is expired (INTCNT=0). SW reads ICNTO to know elapsed time.
NOTE:
As shown in
Figure 2-3
when ICNTB is changed with interrupt manual update (TCON[4] or ICNTB[31]), the new
changed value is applied to interrupt counter (INTCNT) at that time. When ICNTB is changed without interrupt manual update
(TCON[4] or ICNTB[31]) (@ at
Figure 2-3
), the new changed value is applied to INTCNT (interrupt counter) after interrupt
counter expires. When auto reload is needed, write Interrupt Type (TCON[5]) as 1.
Figure 2-4 Timer Operation Without Auto Reload (One-shot mode)
When one-shot mode is needed, set the Interrupt Type (TCON[5]) as 0. After timer is expired, INTCNT (interrupt
counter) is set as 0 and interrupt occurs at every TICK.
2-3