Serial peripheral interface (SPI) RM0351
1438/1830 DocID024597 Rev 5
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
1514131211109876543210
BIDI
MODE
BIDI
OE
CRC
EN
CRC
NEXT
CRCL
RX
ONLY
SSM SSI
LSB
FIRST
SPE BR [2:0] MSTR CPOL CPHA
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
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.
0: 2-line unidirectional data mode selected
1: 1-line bidirectional data mode selected
Bit 14 BIDIOE: Output enable in bidirectional mode
This bit combined with the BIDIMODE bit selects the direction of transfer in bidirectional mode
0: Output disabled (receive-only mode)
1: Output enabled (transmit-only 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
0: CRC calculation disabled
1: CRC calculation Enabled
Note: This bit should be written only when SPI is disabled (SPE = ‘0’) for correct operation.
Bit 12 CRCNEXT: Transmit CRC next
0: Next transmit value is from Tx buffer
1: Next transmit value is from Tx CRC register
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.
0: 8-bit CRC length
1: 16-bit CRC length
Note: This bit should be written only when SPI is disabled (SPE = ‘0’) for correct operation.
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