EFM32WG Datasheet, PDF (124/834 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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11 CMU - Clock Management Unit
0123 4
Oscillat ors
CMU
WDOG clock
LETIMER clock
LCD clock
Peripheral A clock
Peripheral B clock
Peripheral C clock
Peripheral D clock
CPU clock
What?
Quick Facts
The CMU controls oscillators and clocks.
EFM32WG supports five different oscillators
with minimized power consumption and short
start-up time. An additional separate RC
oscillator is used for flash programming and
debug trace. The CMU also has HW support
for calibration of RC oscillators.
Why?
Oscillators and clocks contribute significantly
to the power consumption of the MCU. With
the low power oscillators combined with the
flexible clock control scheme, it is possible
to minimize the energy consumption in any
given application.
How?
The CMU can configure different clock
sources, enable/disable clocks to peripherals
on an individual basis and set the prescaler
for the different clocks. The short oscillator
start-up times makes duty-cycling between
active mode and the different low energy
modes (EM2-4) very efficient. The calibration
feature ensures high accuracy RC oscillators.
Several interrupts are available to avoid CPU
polling of flags.
11.1 Introduction
The Clock Management Unit (CMU) is responsible for controlling the oscillators and clocks on-board the
EFM32WG. The CMU provides the capability to turn on and off the clock on an individual basis to all
peripheral modules in addition to enable/disable and configure the available oscillators. The high degree
of flexibility enables software to minimize energy consumption in any specific application by not wasting
power on peripherals and oscillators that are inactive.
11.2 Features
• Multiple clock sources available:
• 1-28 MHz High Frequency RC Oscillator (HFRCO)
• 4-48 High Frequency Crystal Oscillator (HFXO)
• 32.768 kHz Low Frequency RC Oscillator (LFRCO)
• 1 kHz Ultra Low Frequency RC Oscillator (ULFRCO)
• 32.768 kHz Low Frequency Crystal Oscillator (LFXO)
• Low power oscillators
• Low start-up times
• Separate prescaler for High Frequency Core Clocks (HFCORECLK) and Peripheral Clocks
(HFPERCLK)
• Individual clock prescaler selection for each Low Energy Peripheral
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