Philips LPC213 Series User Manual page 181

LPC2131/2/4/6/8 Pulse Width Modulator is based on standard Timer/Counter 0/1
described in the previous chapter. Application can choose among PWM and match
functions available.
15.1 Features
15.2 Description
The PWM is based on the standard Timer block and inherits all of its features, although
only the PWM function is pinned out on the LPC2131/2/4/6/8. The Timer is designed to
count cycles of the peripheral clock (PCLK) and optionally generate interrupts or perform
other actions when specified timer values occur, based on seven match registers. It also
User manual
UM10120
Chapter 15: Pulse Width Modulator (PWM)
Rev. 01 — 24 June 2005
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Seven match registers allow up to 6 single edge controlled or 3 double edge
controlled PWM outputs, or a mix of both types. The match registers also allow:
– Continuous operation with optional interrupt generation on match.
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
•
An external output for each match register with the following capabilities:
– Set low on match.
– Set high on match.
– Toggle on match.
– Do nothing on match.
•
Supports single edge controlled and/or double edge controlled PWM outputs. Single
edge controlled PWM outputs all go high at the beginning of each cycle unless the
output is a constant low. Double edge controlled PWM outputs can have either edge
occur at any position within a cycle. This allows for both positive going and negative
going pulses.
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Pulse period and width can be any number of timer counts. This allows complete
flexibility in the trade-off between resolution and repetition rate. All PWM outputs will
occur at the same repetition rate.
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Double edge controlled PWM outputs can be programmed to be either positive going
or negative going pulses.
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Match register updates are synchronized with pulse outputs to prevent generation of
erroneous pulses. Software must "release" new match values before they can
become effective.
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May be used as a standard timer if the PWM mode is not enabled.
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A 32-bit Timer/Counter with a programmable 32-bit Prescaler.
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Four 32-bit capture channels take a snapshot of the timer value when an input signal
transitions. A capture event may also optionally generate an interrupt.
Rev. 01 — 24 June 2005
User manual
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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