Serial peripheral interface / integrated interchip sound (SPI/I2S) RM0440
1782/2126 RM0440 Rev 4
39.9.2 SPI control register 2 (SPIx_CR2)
Address offset: 0x04
Reset value: 0x0700
Bit 1 CPOL: Clock polarity
0: CK to 0 when idle
1: CK to 1 when idle
Note: This bit should not be changed when communication is ongoing.
This bit is not used in I
2
S mode and SPI TI mode except the case when CRC is applied
at TI mode.
Bit 0 CPHA: Clock phase
0: The first clock transition is the first data capture edge
1: The second clock transition is the first data capture edge
Note: This bit should not be changed when communication is ongoing.
This bit is not used in I
2
S mode and SPI TI mode except the case when CRC is applied
at TI mode.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Res.
LDMA
_TX
LDMA
_RX
FRXT
H
DS[3:0] TXEIE RXNEIE ERRIE FRF NSSP SSOE TXDMAEN RXDMAEN
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bit 15 Reserved, must be kept at reset value.
Bit 14 LDMA_TX: Last DMA transfer for transmission
This bit is used in data packing mode, to define if the total number of data to transmit by DMA
is odd or even. It has significance only if the TXDMAEN bit in the SPIx_CR2 register is set
and if packing mode is used (data length =< 8-bit and write access to SPIx_DR is 16-bit
wide). It has to be written when the SPI is disabled (SPE = 0 in the SPIx_CR1 register).
0: Number of data to transfer is even
1: Number of data to transfer is odd
Note: Refer to Procedure for disabling the SPI on page 1746 if the CRCEN bit is set.
This bit is not used in I²S mode.
Bit 13 LDMA_RX: Last DMA transfer for reception
This bit is used in data packing mode, to define if the total number of data to receive by DMA
is odd or even. It has significance only if the RXDMAEN bit in the SPIx_CR2 register is set
and if packing mode is used (data length =< 8-bit and write access to SPIx_DR is 16-bit
wide). It has to be written when the SPI is disabled (SPE = 0 in the SPIx_CR1 register).
0: Number of data to transfer is even
1: Number of data to transfer is odd
Note: Refer to Procedure for disabling the SPI on page 1746 if the CRCEN bit is set.
This bit is not used in I²S mode.
Bit 12 FRXTH: FIFO reception threshold
This bit is used to set the threshold of the RXFIFO that triggers an RXNE event
0: RXNE event is generated if the FIFO level is greater than or equal to 1/2 (16-bit)
1: RXNE event is generated if the FIFO level is greater than or equal to 1/4 (8-bit)
Note: This bit is not used in I
2
S mode.
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