Figure 330. Operations Required To Transmit 0X3478Ae; Figure 331. Operations Required To Receive 0X3478Ae; Figure 332. Lsb Justified 16-Bit Extended To 32-Bit Packet Frame With Cpol = 0 - ST STM32F446 Series Reference Manual

Serial peripheral interface/ inter-IC sound (SPI/I2S)
•
In transmission mode:
If data 0x3478AE have to be transmitted, two write operations to the SPIx_DR register
are required by software or by DMA. The operations are shown below.
•
In reception mode:
If data 0x3478AE are received, two successive read operations from the SPIx_DR
register are required on each RXNE event.

Figure 332. LSB justified 16-bit extended to 32-bit packet frame with CPOL = 0

When 16-bit data frame extended to 32-bit channel frame is selected during the I
configuration phase, Only one access to the SPIx_DR register is required. The 16 remaining
bits are forced by hardware to 0x0000 to extend the data to 32-bit format. In this case it
corresponds to the half-word MSB.
If the data to transmit or the received data are 0x76A3 (0x0000 76A3 extended to 32-bit),
the operation shown in
876/1328

Figure 330. Operations required to transmit 0x3478AE

Figure 331. Operations required to receive 0x3478AE

Figure 333 is required.
RM0390 Rev 4
RM0390
2
S