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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
493 of 808
NXP Semiconductors
UM10360
Chapter 24: LPC17xx Pulse Width Modulator (PWM)
values has taken place, all bits of the LER are automatically cleared. Until the
corresponding bit in the PWMLER is set and a PWM Match 0 event occurs, any value
written to the PWM Match registers has no effect on PWM operation.
For example, if PWM2 is configured for double edge operation and is currently running, a
typical sequence of events for changing the timing would be:
•
Write a new value to the PWM Match1 register.
•
Write a new value to the PWM Match2 register.
•
Write to the PWMLER, setting bits 1 and 2 at the same time.
•
The altered values will become effective at the next reset of the timer (when a PWM
Match 0 event occurs).
The order of writing the two PWM Match registers is not important, since neither value will
be used until after the write to LER. This insures that both values go into effect at the
same time, if that is required. A single value may be altered in the same way if needed.
The function of each of the bits in the LER is shown in
.
Table 434: PWM Latch Enable Register (PWM1LER - address 0x4001 8050) bit description
Bit Symbol
Description
Reset
Value
0
Enable PWM
Match 0 Latch
Writing a one to this bit allows the last value written to the PWM
Match 0 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
1
Enable PWM
Match 1 Latch
Writing a one to this bit allows the last value written to the PWM
Match 1 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
2
Enable PWM
Match 2 Latch
Writing a one to this bit allows the last value written to the PWM
Match 2 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
3
Enable PWM
Match 3 Latch
Writing a one to this bit allows the last value written to the PWM
Match 3 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
4
Enable PWM
Match 4 Latch
Writing a one to this bit allows the last value written to the PWM
Match 4 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
5
Enable PWM
Match 5 Latch
Writing a one to this bit allows the last value written to the PWM
Match 5 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
6
Enable PWM
Match 6 Latch
Writing a one to this bit allows the last value written to the PWM
Match 6 register to be become effective when the timer is next reset
by a PWM Match event. See
Section 24–7.4 “PWM Match Control
Register (PWM1MCR - 0x4001 8014)”
0
7
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA