EFM32WG Datasheet, PDF (579/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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23 LETIMER - Low Energy Timer
0123 4
RTC
LETIM ER
What?
Quick Facts
The LETIMER is a down-counter that can
keep track of time and output configurable
waveforms. Running on a 32.768 kHz clock
the LETIMER is available even in EM2 with
sub µA current consumption.
Why?
The LETIMER can be used to provide
repeatable waveforms to external
components while remaining in EM2. It is well
suited for e.g. metering systems or to provide
more compare values than available in the
RTC.
How?
With buffered repeat and top value registers,
the LETIMER can provide glitch-free
waveforms at frequencies up to 16 kHz.
It is tightly coupled to the RTC, which
allows advanced time-keeping and wake-up
functions in EM2.
23.1 Introduction
The unique LETIMER^TM, the Low Energy Timer, is a 16-bit timer that is available in energy mode EM2
in addition to EM1 and EM0. Because of this, it can be used for timing and output generation when most
of the device is powered down, allowing simple tasks to be performed while the power consumption of
the system is kept at an absolute minimum.
The LETIMER can be used to output a variety of waveforms with minimal software intervention. It is
also connected to the Real Time Counter (RTC), and can be configured to start counting on compare
matches from the RTC.
23.2 Features
• 16-bit down count timer
• 2 Compare match registers
• Compare register 0 can be top timer top value
• Compare registers can be double buffered
• Double buffered 8-bit Repeat Register
• Same clock source as the Real Time Counter
• LETIMER can be triggered (started) by an RTC event or by software
• 2 output pins can optionally be configured to provide different waveforms on timer underflow:
• Toggle output pin
• Apply a positive pulse (pulse width of one LFACLK_LETIMER period)
• PWM
• Interrupt on:
• Compare matches
• Timer underflow
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
579
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