Datasheet
LPC11U1X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 2.2 — 11 March 2014 22 of 72
NXP Semiconductors
LPC11U1x
32-bit ARM Cortex-M0 microcontroller
• Four match registers per timer that 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.
• Up to four external outputs corresponding to match registers, with the following
capabilities:
– Set LOW on match.
– Set HIGH on match.
– Toggle on match.
– Do nothing on match.
• The timer and prescaler may be configured to be cleared on a designated capture
event. This feature permits easy pulse-width measurement by clearing the timer on
the leading edge of an input pulse and capturing the timer value on the trailing edge.
7.14 System tick timer
The ARM Cortex-M0 includes a system tick timer (SYSTICK) that is intended to generate
a dedicated SYSTICK exception at a fixed time interval (typically 10 ms).
7.15 Windowed WatchDog Timer (WWDT)
The purpose of the watchdog is to reset the controller if software fails to periodically
service it within a programmable time window.
7.15.1 Features
• Internally resets chip if not periodically reloaded during the programmable time-out
period.
• Optional windowed operation requires reload to occur between a minimum and
maximum time period, both programmable.
• Optional warning interrupt can be generated at a programmable time prior to
watchdog time-out.
• Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be
disabled.
• Incorrect feed sequence causes reset or interrupt if enabled.
• Flag to indicate watchdog reset.
• Programmable 24-bit timer with internal prescaler.
• Selectable time period from (T
cy(WDCLK)
256 4) to (T
cy(WDCLK)
2
24
4) in
multiples of T
cy(WDCLK)
4.
• The Watchdog Clock (WDCLK) source can be selected from the IRC or the dedicated
watchdog oscillator (WDO). This gives a wide range of potential timing choices of
watchdog operation under different power conditions.