Serial peripheral interface (SPI)
RM0090
894/1731
DocID018909 Rev 11
Figure 264. I
2
S Philips protocol waveforms (16/32-bit full accuracy, CPOL = 0)
Data are latched on the falling edge of CK (for the transmitter) and are read on the rising
edge (for the receiver). The WS signal is also latched on the falling edge of CK.
Figure 265. I
2
S Philips standard waveforms (24-bit frame with CPOL = 0)
This mode needs two write or read operations to/from the SPI_DR.
•
In transmission mode:
if 0x8EAA33 has to be sent (24-bit):
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