ST STM32F102 Series Reference Manual page 570

Serial peripheral interface (SPI)
Bit 15 BIDIMODE: Bidirectional data mode enable
0: 2-line unidirectional data mode selected
1: 1-line bidirectional data mode selected
Note: Not used in I2S mode
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)
Notes: In master mode, the MOSI pin is used and in slave mode, the MISO pin is used.
Not used in I
Bit 13 CRCEN: Hardware CRC calculation enable
0: CRC calculation disabled
1: CRC calculation Enabled
Notes: This bit should be written only when SPI is disabled (SPE = '0') for correct operation
Not used in I
Bit 12 CRCNEXT: Transmit CRC next
0: Next transmit value is from Tx buffer
1: Next transmit value is from Tx CRC register
Notes: This bit has to be written as soon as the last data is written into the SPI_DR register.
Not used in I
Bit 11 DFF: Data Frame Format
0: 8-bit data frame format is selected for transmission/reception
1: 16-bit data frame format is selected for transmission/reception
Notes: This bit should be written only when SPI is disabled (SPE = '0') for correct operation
Not used in I2S mode
Bit 10 RXONLY: Receive only
This bit combined with the BIDImode bit selects the direction of transfer in 2-line unidirectional
mode. This bit is also useful in a multislave system in which this particular slave is not accessed,
the output from the accessed slave is not corrupted.
0: Full duplex (Transmit and receive)
1: Output disabled (Receive-only mode)
Note: Not used in I
Bit 9 SSM: Software slave management
When the SSM bit is set, the NSS pin input is replaced with the value from the SSI bit.
0: Software slave management disabled
1: Software slave management enabled
Note: Not used in I
Bit 8 SSI: Internal slave select
This bit has an effect only when the SSM bit is set. The value of this bit is forced onto the NSS pin
and the I/O value of the NSS pin is ignored.
Note: Not used in I
Bit 7 LSBFIRST: Frame Format
0: MSB transmitted first
1: LSB transmitted first
Notes: This bit should not be changed when communication is ongoing.
Not used in I
570/690
2
S mode
2
S mode
2
S mode
2
S mode
2
S mode
2
S mode
2
S mode
RM0008