ST STM32F40 Series

Serial peripheral interface (SPI) RM0090
825/1422 Doc ID 018909 Rev 4
MSB justified standard
For this standard, the WS signal is generated at the same time as the first data bit, which is
the MSBit.
Figure 295. MSB Justified 16-bit or 32-bit full-accuracy length with CPOL = 0
Data are latched on the falling edge of CK (for transmitter) and are read on the rising edge
(for the receiver).
Figure 296. MSB Justified 24-bit frame length with CPOL = 0
Figure 297. MSB Justified 16-bit extended to 32-bit packet frame with CPOL = 0
MSB LSB MSB
CK
WS
SD
Channel left
Channel right
May be 16-bit, 32-bit
Transmission
Reception
CK
WS
SD
Channel left 32-bit
Channel right
MSB
LSB
8-bit remaining
0 forced
24-bit data
Transmission
Reception
CK
WS
SD
Channel left 32-bit
Channel right
MSB
LSB
16-bit remaining
0 forced
16-bit data
Transmission
Reception