LPC2212 Philips Semiconductors (Acquired by NXP), LPC2212 Datasheet - Page 23

• Manufacturer Part Number: LPC2212
• Description: 16/32-bit Arm Microcontrollers; 128/256 KB Isp/iap Flash With 10-bit ADC And External Memory Interfacebased on a 16/32 Bit ARM7TDMI-STM Cpu With Real-time Emulation And Embedded Trace Support, Together With 128/256 Kilobytes (kB) of Embedded High Spe
• Manufacturer: Philips Semiconductors (Acquired by NXP)

Philips Semiconductors
9397 750 12747
Preliminary data
6.19.1 Features
6.19 Pulse width modulator
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 LPC2212/LPC2214. 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. The PWM function is also based on match register events.
The ability to separately control rising and falling edge locations allows the PWM to
be used for more applications. For instance, multi-phase motor control typically
requires three non-overlapping PWM outputs with individual control of all three pulse
widths and positions.
Two match registers can be used to provide a single edge controlled PWM output.
One match register (MR0) controls the PWM cycle rate, by resetting the count upon
match. The other match register controls the PWM edge position. Additional single
edge controlled PWM outputs require only one match register each, since the
repetition rate is the same for all PWM outputs. Multiple single edge controlled PWM
outputs will all have a rising edge at the beginning of each PWM cycle, when an MR0
match occurs.
Three match registers can be used to provide a PWM output with both edges
controlled. Again, the MR0 match register controls the PWM cycle rate. The other
match registers control the two PWM edge positions. Additional double edge
controlled PWM outputs require only two match registers each, since the repetition
rate is the same for all PWM outputs.
With double edge controlled PWM outputs, specific match registers control the rising
and falling edge of the output. This allows both positive going PWM pulses (when the
rising edge occurs prior to the falling edge), and negative going PWM pulses (when
the falling edge occurs prior to the rising edge).
•
•
•
•
•
Seven match registers allow up to six single edge controlled or three double edge
controlled PWM outputs, or a mix of both types.
The match registers also allow:
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.
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.
Double edge controlled PWM outputs can be programmed to be either positive
going or negative going pulses.
– Continuous operation with optional interrupt generation on match.
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
Rev. 01 — 02 February 2004
16/32-bit ARM microcontrollers with external memory interface
LPC2212/LPC2214
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
23 of 39