EFM32WG890 Datasheet, PDF (7/85 Pages) Silicon Laboratories – Operation from backup battery when main power drains out

...the world's most energy friendly microcontrollers
is capable of supporting a wide range of sensors and measurement schemes, and can for instance mea-
sure LC sensors, resistive sensors and capacitive sensors. LESENSE also includes a programmable
FSM which enables simple processing of measurement results without CPU intervention. LESENSE is
available in energy mode EM2, in addition to EM0 and EM1, making it ideal for sensor monitoring in
applications with a strict energy budget.
2.1.28 Backup Power Domain
The backup power domain is a separate power domain containing a Backup Real Time Counter, BURTC,
and a set of retention registers, available in all energy modes. This power domain can be configured to
automatically change power source to a backup battery when the main power drains out. The backup
power domain enables the EFM32WG890 to keep track of time and retain data, even if the main power
source should drain out.
2.1.29 Advanced Encryption Standard Accelerator (AES)
The AES accelerator performs AES encryption and decryption with 128-bit or 256-bit keys. Encrypting or
decrypting one 128-bit data block takes 52 HFCORECLK cycles with 128-bit keys and 75 HFCORECLK
cycles with 256-bit keys. The AES module is an AHB slave which enables efficient access to the data
and key registers. All write accesses to the AES module must be 32-bit operations, i.e. 8- or 16-bit
operations are not supported.
2.1.30 General Purpose Input/Output (GPIO)
In the EFM32WG890, there are 90 General Purpose Input/Output (GPIO) pins, which are divided into
ports with up to 16 pins each. These pins can individually be configured as either an output or input. More
advanced configurations like open-drain, filtering and drive strength can also be configured individually
for the pins. The GPIO pins can also be overridden by peripheral pin connections, like Timer PWM
outputs or USART communication, which can be routed to several locations on the device. The GPIO
supports up to 16 asynchronous external pin interrupts, which enables interrupts from any pin on the
device. Also, the input value of a pin can be routed through the Peripheral Reflex System to other
peripherals.
2.1.31 Liquid Crystal Display Driver (LCD)
The LCD driver is capable of driving a segmented LCD display with up to 8x36 segments. A voltage
boost function enables it to provide the LCD display with higher voltage than the supply voltage for the
device. In addition, an animation feature can run custom animations on the LCD display without any
CPU intervention. The LCD driver can also remain active even in Energy Mode 2 and provides a Frame
Counter interrupt that can wake-up the device on a regular basis for updating data.
2.2 Configuration Summary
The features of the EFM32WG890 is a subset of the feature set described in the EFM32WG Reference
Manual. Table 2.1 (p. 7) describes device specific implementation of the features.
Table 2.1. Configuration Summary
Module
Configuration
Pin Connections
Cortex-M4
Full configuration
NA
DBG
Full configuration
DBG_SWCLK, DBG_SWDIO,
DBG_SWO
MSC
Full configuration
NA
DMA
Full configuration
NA
RMU
Full configuration
NA
EMU
Full configuration
NA
2014-06-13 - EFM32WG890FXX - d0198_Rev1.40
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