Datasheet
LPC2114_2124 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 7 — 10 June 2011 18 of 42
NXP Semiconductors
LPC2114/2124
Single-chip 16/32-bit microcontrollers
6.13.2 Features available in LPC2114/2124/01 only
• 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 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 CAPn input can not be
shorter than 1 / (2PCLK).
6.14 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.
6.14.1 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 pre-scaler.
• Selectable time period from (T
cy(PCLK)
256 4) to (T
cy(PCLK)
2
32
4) in multiples of
T
cy(PCLK)
4.
6.15 Real-time clock
The 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).
6.15.1 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.