Datasheet

Functional overview STM32L071xx
32/144 DS10690 Rev 6
3.15.2 Universal synchronous/asynchronous receiver transmitter (USART)
The four USART interfaces (USART1, USART2, USART4 and USART5) are able to
communicate at speeds of up to 4 Mbit/s.
They provide hardware management of the CTS, RTS and RS485 driver enable (DE)
signals, multiprocessor communication mode, master synchronous communication and
single-wire half-duplex communication mode. USART1 and USART2 also support
SmartCard communication (ISO 7816), IrDA SIR ENDEC, LIN Master/Slave capability, auto
baud rate feature and has a clock domain independent from the CPU clock, allowing to
wake up the MCU from Stop mode using baudrates up to 42 Kbaud.
All USART interfaces can be served by the DMA controller.
Table 12 for the supported modes and features of USART interfaces.
3.15.3 Low-power universal asynchronous receiver transmitter (LPUART)
The devices embed one Low-power UART. The LPUART supports asynchronous serial
communication with minimum power consumption. It supports half duplex single wire
communication and modem operations (CTS/RTS). It allows multiprocessor
communication.
The LPUART has a clock domain independent from the CPU clock. It can wake up the
system from Stop mode using baudrates up to 46 Kbaud. The Wakeup events from Stop
mode are programmable and can be:
• Start bit detection
• Or any received data frame
• Or a specific programmed data frame
Table 12. USART implementation
USART modes/features
(1)
1. X = supported.
USART1 and USART2 USART4 and USART5
Hardware flow control for modem X X
Continuous communication using DMA X X
Multiprocessor communication X X
Synchronous mode
(2)
2. This mode allows using the USART as an SPI master.
XX
Smartcard mode X -
Single-wire half-duplex communication X X
IrDA SIR ENDEC block X -
LIN mode X -
Dual clock domain and wakeup from Stop mode X -
Receiver timeout interrupt X -
Modbus communication X -
Auto baud rate detection (4 modes) X -
Driver Enable X X
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