ST STM32L4x6 Reference Manual page 1274

Low-power universal asynchronous receiver transmitter (LPUART)
Bit 13 DDRE: DMA Disable on Reception Error
Note: The reception errors are: parity error, framing error or noise error.
Bit 12 OVRDIS: Overrun Disable
Note: This control bit allows checking the communication flow without reading the data.
Bit 11 Reserved, must be kept at reset value.
Bit 10 CTSIE: CTS interrupt enable
Bit 9 CTSE: CTS enable
Bit 8 RTSE: RTS enable
Bit 7 DMAT: DMA enable transmitter
Bit 6 DMAR: DMA enable receiver
Bits 5:4 Reserved, must be kept at reset value.
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0: DMA is not disabled in case of reception error. The corresponding error flag is set but
RXNE is kept 0 preventing from overrun. As a consequence, the DMA request is not
asserted, so the erroneous data is not transferred (no DMA request), but next correct
received data will be transferred.
1: DMA is disabled following a reception error. The corresponding error flag is set, as well
as RXNE. The DMA request is masked until the error flag is cleared. This means that the
software must first disable the DMA request (DMAR = 0) or clear RXNE before clearing the
error flag.
This bit can only be written when the LPUART is disabled (UE=0).
This bit is used to disable the receive overrun detection.
0: Overrun Error Flag, ORE, is set when received data is not read before receiving new
data.
1: Overrun functionality is disabled. If new data is received while the RXNE flag is still set
the ORE flag is not set and the new received data overwrites the previous content of the
LPUART_RDR register.
This bit can only be written when the LPUART is disabled (UE=0).
0: Interrupt is inhibited
1: An interrupt is generated whenever CTSIF=1 in the LPUART_ISR register
0: CTS hardware flow control disabled
1: CTS mode enabled, data is only transmitted when the CTS input is asserted (tied to 0). If
the CTS input is de-asserted while data is being transmitted, then the transmission is
completed before stopping. If data is written into the data register while CTS is de-asserted,
the transmission is postponed until CTS is asserted.
This bit can only be written when the LPUART is disabled (UE=0)
0: RTS hardware flow control disabled
1: RTS output enabled, data is only requested when there is space in the receive buffer. The
transmission of data is expected to cease after the current character has been transmitted.
The RTS output is asserted (pulled to 0) when data can be received.
This bit can only be written when the LPUART is disabled (UE=0).
This bit is set/reset by software
1: DMA mode is enabled for transmission
0: DMA mode is disabled for transmission
This bit is set/reset by software
1: DMA mode is enabled for reception
0: DMA mode is disabled for reception
DocID024597 Rev 3
RM0351