LPC2220 PHILIPS [NXP Semiconductors], LPC2220 Datasheet - Page 25

• Manufacturer Part Number: LPC2220
• Description: 16/32-bit ARM microcontrollers; flashless with 64 kB, with 10-bit ADC and external memory interface
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14061
Product data sheet
6.16.1 Features
6.17.1 Features
6.17 Watchdog timer
The LPC2220 can count external events on one of the capture inputs if the minimum
external pulse is equal or longer than a period of the PCLK. In this configuration, unused
capture lines can be selected as regular timer capture inputs.
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.
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A 32-bit Timer/Counter with a programmable 32-bit Prescaler.
Timer operation (LPC2210/2220) or external Event Counter (LPC2220 only).
Four 32-bit capture channels per timer/counter that can take a snapshot of the timer
value when an input signal transitions. A capture event may also optionally generate
an interrupt.
Four 32-bit match registers 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.
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
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
16/32-bit ARM microcontrollers with external memory interface
Rev. 02— 30 May 2005
pclk
256
4) to (t
pclk
2
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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LPC2210/2220
4) in multiples of t
pclk
25 of 49
4.