8.17.1 Features
• Internally resets chip if not periodically reloaded during the programmable time-out
period.
• Optional windowed operation requires reload to occur between a minimum and
maximum time period, both programmable.
• Optional warning interrupt can be generated at a programmable time prior to
watchdog time-out.
• Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be
disabled.
• Incorrect feed sequence causes reset or interrupt if enabled.
• Flag to indicate watchdog reset.
• Programmable 24-bit timer with internal prescaler.
• Selectable time period from (Tcy(WDCLK) to (Tcy(WDCLK) 24 n
multiples of Tcy(WDCLK)
• The Watchdog Clock (WDCLK) source can be selected from the internal RC oscillator
(IRC), or the dedicated watchdog oscillator (WDOsc). This gives a wide range of
potential timing choices of watchdog operation under different power conditions.
8.18 Self Wake-up Timer (WKT)
The self wake-up timer is a 32-bit, loadable down-counter. Writing any non-zero value to
this timer automatically enables the counter and launches a count-down sequence. When
the counter is used as a wake-up timer, this write can occur just prior to entering a
reduced power mode.
8.18.1 Features
• 32-bit loadable down-counter. Counter starts automatically when a count value is
loaded. Time-out generates an interrupt/wake up request.
• The WKT resides in a separate, always-on power domain.
• The WKT supports two clock sources: the low-power oscillator and the IRC. The
low-power oscillator is located in the always-on power domain, so it can be used as
the clock source in Deep power-down mode.
• The WKT can be used for waking up the part from any reduced power mode,
including Deep power-down mode, or for general-purpose timing.
8.19 SysTick timer
The ARM Cortex-M0+ 24-bit SysTick timer is implemented on the LPC81xM.
8.20 Analog comparator (ACMP)
The analog comparator with selectable hysteresis can compare voltage levels on external
pins and internal voltages.
After power-up and after switching the input channels of the comparator, the output of th