Figure 363. I 2 S Philips Protocol Waveforms (16/32-Bit Full Accuracy); Figure 364. I 2 S Philips Standard Waveforms (24-Bit Frame) - ST STM32WL5 Series Reference Manual

Serial peripheral interface / integrated interchip sound (SPI/I2S)
For all data formats and communication standards, the most significant bit is always sent
first (MSB first).
2
The I S interface supports four audio standards, configurable using the I2SSTD[1:0] and
PCMSYNC bits in the SPIx_I2SCFGR register.
2
I S Philips standard
For this standard, the WS signal is used to indicate which channel is being transmitted. It is
activated one CK clock cycle before the first bit (MSB) is available.
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.
CK
WS
SD
This mode needs two write or read operations to/from the SPIx_DR register.
•
In transmission mode:
If 0x8EAA33 has to be sent (24-bit):
1296/1461
2
Figure 363. I S Philips protocol waveforms (16/32-bit full accuracy)
CK
WS
SD
MSB
2
Figure 364. I S Philips standard waveforms (24-bit frame)
Transmission
24-bit data
MSB
Channel left 32-bit
transmission reception
Can be 16-bit or 32-bit
Channel left
Reception
8-bit remaining 0 forced
LSB
RM0453 Rev 1
LSB MSB
Channel
right
MS19591V1
Channel right
MS19592V1
RM0453