Leuart - Low Energy Universal Asynchronous Receiver/Transmitter; Introduction - Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual

19. LEUART - Low Energy Universal Asynchronous Receiver/Transmitter

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DMA
controller
LEUART

19.1 Introduction

The unique Low Energy UART (LEUART) is a UART that allows two-way UART communication on a strict power budget. Only a 32.768
kHz clock is needed to allow UART communication up to 9600 baud.
Even when the system is in low energy mode EM2 Deep Sleep (with most core functionality turned off), the LEUART can wait for an
incoming UART frame while having an extremely low energy consumption. When a UART frame is completely received, the CPU can
quickly be woken up. Alternatively, multiple frames can be transferred via the Direct Memory Access (DMA) module into RAM memory
before waking up the CPU.
Received data can optionally be blocked until a configurable start frame is detected. A signal frame can be configured to generate an
interrupt indicating the end of a data transmission. The start frame and signal frame can be used in combination to handle higher level
communication protocols.
Similarly, data can be transmitted in EM2 Deep Sleep either on a frame-by-frame basis with data from the CPU or through use of the
DMA.
The LEUART includes all necessary hardware support to make asynchronous serial communication possible with minimal software
overhead and low energy consumption.
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LEUART - Low Energy Universal Asynchronous Receiver/Transmitter
RAM
RX
TX
Quick Facts
What?
The LEUART provides full UART communication us-
ing a low frequency 32.768 kHz clock, and has spe-
cial features for communication without CPU inter-
vention.
Why?
It allows UART communication to be performed in
low energy modes, using only a few µA during active
communication and only 150 nA when waiting for in-
coming data.
How?
A low frequency clock signal allows communication
with less energy. Using DMA, the LEUART can
transmit and receive data with minimal CPU inter-
vention. Special UART-frames can be configured to
help control the data flow, further automating data
transmission.
Reference Manual
Rev. 1.1 | 615