ST STM32L4 5 Series Reference Manual page 1438

Serial peripheral interface (SPI)
42.6 SPI registers
The peripheral registers can be accessed by half-words (16-bit) or words (32-bit). SPI_DR
in addition by can be accessed by 8-bit access.
42.6.1 SPI control register 1 (SPIx_CR1)
Address offset: 0x00
Reset value: 0x0000
15 14 13
BIDI BIDI CRC CRC
MODE OE EN NEXT
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Bit 15 BIDIMODE: Bidirectional data mode enable. This bit enables half-duplex communication using
common single bidirectional data line. Keep RXONLY bit clear when bidirectional mode is
active.
Bit 14 BIDIOE: Output enable in bidirectional mode
This bit combined with the BIDIMODE bit selects the direction of transfer in bidirectional mode
Note: In master mode, the MOSI pin is used and in slave mode, the MISO pin is used.
Bit 13 CRCEN: Hardware CRC calculation enable
Note: This bit should be written only when SPI is disabled (SPE = '0') for correct operation.
Bit 12 CRCNEXT: Transmit CRC next
Note: This bit has to be written as soon as the last data is written in the SPIx_DR register.
Bit 11 CRCL: CRC length
This bit is set and cleared by software to select the CRC length.
Note: This bit should be written only when SPI is disabled (SPE = '0') for correct operation.
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12 11 10 9
RX
CRCL SSM
ONLY
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0: 2-line unidirectional data mode selected
1: 1-line bidirectional data mode selected
0: Output disabled (receive-only mode)
1: Output enabled (transmit-only mode)
0: CRC calculation disabled
1: CRC calculation Enabled
0: Next transmit value is from Tx buffer
1: Next transmit value is from Tx CRC register
0: 8-bit CRC length
1: 16-bit CRC length
8 7 6
LSB
SSI SPE
FIRST
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DocID024597 Rev 5
5 4 3 2
BR [2:0] MSTR
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RM0351
1 0
CPOL CPHA
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