UM10462
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User manual
Rev. 5.5 — 21 December 2016
365 of 523
NXP Semiconductors
UM10462
Chapter 16: LPC11U3x/2x/1x 32-bit counter/timers CT32B0/1
HIGH. The timer is reset by the match register that is configured to set the PWM cycle
length. When the timer is reset to zero, all currently HIGH match outputs configured as
PWM outputs are cleared.
16.7.13 Rules for single edge controlled PWM outputs
1. All single edge controlled PWM outputs go LOW at the beginning of each PWM cycle
(timer is set to zero) unless their match value is equal to zero.
2. Each PWM output will go HIGH when its match value is reached. If no match occurs
(i.e. the match value is greater than the PWM cycle length), the PWM output remains
continuously LOW.
3. If a match value larger than the PWM cycle length is written to the match register, and
the PWM signal is HIGH already, then the PWM signal will be cleared with the start of
the next PWM cycle.
4. If a match register contains the same value as the timer reset value (the PWM cycle
length), then the PWM output will be reset to LOW on the next clock tick after the
timer reaches the match value. Therefore, the PWM output will always consist of a
one clock tick wide positive pulse with a period determined by the PWM cycle length
(i.e. the timer reload value).
5. If a match register is set to zero, then the PWM output will go to HIGH the first time the
timer goes back to zero and will stay HIGH continuously.
Table 335: PWM Control Register (PWMC, 0x4001 4074 (CT32B0) and 0x4001 8074 (CT32B1))
bit description
Bit
Symbol
Value
Description
Reset
value
0
PWMEN0
PWM mode enable for channel0.
0
0
CT32Bn_MAT0 is controlled by EM0.
1
PWM mode is enabled for CT32Bn_MAT0.
1
PWMEN1
PWM mode enable for channel1.
0
0
CT32Bn_MAT01 is controlled by EM1.
1
PWM mode is enabled for CT32Bn_MAT1.
2
PWMEN2
PWM mode enable for channel2.
0
0
CT32Bn_MAT2 is controlled by EM2.
1
PWM mode is enabled for CT32Bn_MAT2.
3
PWMEN3
PWM mode enable for channel3.
Note:
It is
recommended to use match channel 3 to set the PWM
cycle.
0
0
CT32Bn_MAT3 is controlled by EM3.
1
PWM mode is enabled for CT132Bn_MAT3.
31:4
-
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
NA