UM10429
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User manual
Rev. 1 — 20 October 2010
115 of 258
NXP Semiconductors
UM10429
Chapter 12: LPC1102 16-bit counter/timers (CT16B0/1)
12.8 Example timer operation
shows a timer configured to reset the count and generate an interrupt on match.
The prescaler is set to 2 and the match register set to 6. At the end of the timer cycle
where the match occurs, the timer count is reset. This gives a full length cycle to the
match value. The interrupt indicating that a match occurred is generated in the next clock
after the timer reached the match value.
shows a timer configured to stop and generate an interrupt on match. The
prescaler is again set to 2 and the match register set to 6. In the next clock after the timer
reaches the match value, the timer enable bit in TCR is cleared, and the interrupt
indicating that a match occurred is generated.
Fig 21. Sample PWM waveforms with a PWM cycle length of 100 (selected by MR3) and
MAT3:0 enabled as PWM outputs by the PWCON register.
100
(counter is reset)
0
41
65
PWM0/MAT0
PWM1/MAT1
PWM2/MAT2
MR2 = 100
MR1 = 41
MR0 = 65
Fig 22. A timer cycle in which PR=2, MRx=6, and both interrupt and reset on match are enabled
PCLK
prescale
counter
interrupt
timer
counter
timer counter
reset
2
2
2
2
0
0
0
0
1
1
1
1
4
5
6
0
1
Fig 23. A timer cycle in which PR=2, MRx=6, and both interrupt and stop on match are enabled
PCLK
prescale counter
interrupt
timer counter
TCR[0]
(counter enable)
2
2
0
0
1
4
5
6
1
0
