lpc2377 NXP Semiconductors, lpc2377 Datasheet - Page 28

• Manufacturer Part Number: lpc2377
• Description: Single-chip 16-bit/32-bit Microcontroller; 512 Kb ?ash With Isp/iap, Ethernet, Usb 2.0, Can, And 10-bit Adc/dac
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2377_78_4
Product data sheet
7.23.1 Features
7.23 Watchdog timer
7.24 RTC and battery RAM
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 RTC is a set of counters for measuring time when system power is on, and optionally
when it is off. It uses little power in Power-down mode. On the LPC2377/78, the RTC can
be clocked by a separate 32.768 kHz oscillator or by a programmable prescale divider
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Supports single edge controlled and/or double edge controlled PWM outputs. Single
edge controlled PWM outputs all go high at the beginning of each cycle unless the
output is a constant low. Double edge controlled PWM outputs can have either edge
occur at any position within a cycle. This allows for both positive going and negative
going pulses.
Pulse period and width can be any number of timer counts. This allows complete
flexibility in the trade-off between resolution and repetition rate. All PWM outputs will
occur at the same repetition rate.
Double edge controlled PWM outputs can be programmed to be either positive going
or negative going pulses.
Match register updates are synchronized with pulse outputs to prevent generation of
erroneous pulses. Software must ‘release’ new match values before they can become
effective.
May be used as a standard timer if the PWM mode is not enabled.
A 32-bit Timer/Counter with a programmable 32-bit Prescaler.
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
multiples of T
The Watchdog Clock (WDCLK) source can be selected from the RTC clock, the
Internal RC oscillator (IRC), or the APB peripheral clock. This gives a wide range of
potential timing choices of Watchdog operation under different power reduction
conditions. It also provides the ability to run the WDT from an entirely internal source
that is not dependent on an external crystal and its associated components and
wiring, for increased reliability.
cy(WDCLK)
Rev. 04 — 19 November 2008
4.
cy(WDCLK)
256
Single-chip 16-bit/32-bit microcontroller
4) to (T
cy(WDCLK)
LPC2377/78
© NXP B.V. 2008. All rights reserved.
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