Figure 265. I S Philips Protocol Waveforms (16/32-Bit Full Accuracy, Cpol = 0); Figure 266. I S Philips Standard Waveforms (24-Bit Frame With Cpol = 0) - ST STM32F207 Series Reference Manual

Serial peripheral interface (SPI)
2
The I S interface supports four audio standards, configurable using the I2SSTD[1:0] and
PCMSYNC bits in the SPI_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.
Figure 265. I
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 266. I
CK
WS
SD
This mode needs two write or read operations to/from the SPI_DR.
•
In transmission mode:
if 0x8EAA33 has to be sent (24-bit):
710/1381
2
S Philips protocol waveforms (16/32-bit full accuracy, CPOL = 0)
CK
WS
transmission
SD
MSB
2
S Philips standard waveforms (24-bit frame with CPOL = 0)
Transmission Reception
24-bit data
MSB
LSB
Channel left 32-bit
RM0033 Rev 9
reception
Can be 16-bit or 32-bit
Channel left
8-bit remaining 0 forced
RM0033
LSB MSB
Channel
right
MS19591V1
Channel right
MS19592V1