LPC2131_32_34_36_38 NXP Semiconductors, LPC2131_32_34_36_38 Datasheet - Page 20



Manufacturer Part Number
The LPC2131/32/34/36/38 microcontrollers are based on a 16/32-bit ARM7TDMI-S CPUwith real-time emulation and embedded trace support, that combine the microcontrollerwith 32 kB, 64 kB, 128 kB, 256 kB and 512 kB of embedded high-speed flash memory
NXP Semiconductors
NXP Semiconductors
Product data sheet
6.15.1 Features
6.16.1 Features
6.15 Watchdog timer
6.16 Real-time clock
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.
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).
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
Four external outputs per timer/counter corresponding to match registers, with the
following capabilities:
– Set LOW on match.
– Set HIGH on match.
– Toggle on match.
– Do nothing on match.
Internally resets chip if not periodically reloaded.
Debug mode.
Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be
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
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.
Can use either the RTC dedicated 32 kHz oscillator input or clock derived from the
external crystal/oscillator input at XTAL1. Programmable Reference Clock Divider
allows fine adjustment of the RTC.
Dedicated power supply pin can be connected to a battery or the main 3.3 V.
 4.
All information provided in this document is subject to legal disclaimers.
Rev. 5.1 — 29 July 2011
 256  4) to (T
Single-chip 16/32-bit microcontrollers
 2
 4) in multiples of
© NXP B.V. 2011. All rights reserved.
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