Datasheet
LPC2292_2294 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 8 — 8 June 2011 23 of 54
NXP Semiconductors
LPC2292/2294
16/32-bit ARM microcontrollers with external memory interface
6.15.2 Features available in LPC2292/2294/01 only
The LPC2292/2294/01 can count external events on one of the capture inputs if the
external pulse lasts at least one half of the period of the PCLK. In this configuration,
unused capture lines can be selected as regular timer capture inputs, or used as external
interrupts.
• Timer can count cycles of either the peripheral clock (PCLK) or an externally supplied
clock.
• When counting cycles of an externally supplied clock, only one of the timer’s capture
inputs can be selected as the timer’s clock. The rate of such a clock is limited to
PCLK / 4. Duration of HIGH/LOW levels on the selected CAP input cannot be shorter
than 1 / (2PCLK).
6.16 Watchdog timer
The purpose of the watchdog is to reset the microcontroller within a reasonable amount of
time if it enters an erroneous state. When enabled, the watchdog will generate a system
reset if the user program fails to ‘feed’ (or reload) the watchdog within a predetermined
amount of time.
6.16.1 Features
• Internally resets chip if not periodically reloaded.
• Debug mode.
• Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be
disabled.
• Incorrect/incomplete feed sequence causes reset/interrupt if enabled.
• Flag to indicate watchdog reset.
• Programmable 32-bit timer with internal prescaler.
• Selectable time period from (T
cy(PCLK)
256 4) to (T
cy(PCLK)
2
32
4) in multiples of
T
cy(PCLK)
4.
6.17 Real-time clock
The Real-Time Clock (RTC) is designed to provide a set of counters to measure time
when normal or idle operating mode is selected. The RTC has been designed to use little
power, making it suitable for battery powered systems where the CPU is not running
continuously (Idle mode).
6.17.1 Features
• Measures the passage of time to maintain a calendar and clock.
• Ultra-low power design to support battery powered systems.
• Provides Seconds, Minutes, Hours, Day of Month, Month, Year, Day of Week, and
Day of Year.
• Programmable Reference Clock Divider allows adjustment of the RTC to match
various crystal frequencies.