Datasheet
DocID027100 Rev 4 35/149
STM32L072xx Functional overview
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3.17.3 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
Only a 32.768 kHz clock (LSE) is needed to allow LPUART communication up to 9600
baud. Therefore, even in Stop mode, the LPUART can wait for an incoming frame while
having an extremely low energy consumption. Higher speed clock can be used to reach
higher baudrates.
LPUART interface can be served by the DMA controller.
3.17.4 Serial peripheral interface (SPI)/Inter-integrated sound (I2S)
Up to two SPIs are able to communicate at up to 16 Mbits/s in slave and master modes in
full-duplex and half-duplex communication modes. The 3-bit prescaler gives 8 master mode
frequencies and the frame is configurable to 8 bits or 16 bits. The hardware CRC
generation/verification supports basic SD Card/MMC modes.
The USARTs with synchronous capability can also be used as SPI master.
One standard I2S interfaces (multiplexed with SPI2) is available. It can operate in master or
slave mode, and can be configured to operate with a 16-/32-bit resolution as input or output
channels. Audio sampling frequencies from 8 kHz up to 192 kHz are supported. When the
I2S interfaces is configured in master mode, the master clock can be output to the external
DAC/CODEC at 256 times the sampling frequency.
The SPIs can be served by the DMA controller.
Refer to Table 14 for the differences between SPI1 and SPI2.
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
1. X = supported.
2. This mode allows using the USART as an SPI master.
Table 13. USART implementation (continued)
USART modes/features
(1)
USART1 and USART2 USART4 and USART5
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