RM0401 Rev 3 707/771
RM0401 Serial peripheral interface/ inter-IC sound (SPI/I2S)
731
The I
2
S interface supports four audio standards, configurable using the I2SSTD[1:0] and
PCMSYNC bits in the SPIx_I2SCFGR register.
I
2
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 254. 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 255. I
2
S Philips standard waveforms (24-bit frame with CPOL = 0)
This mode needs two write or read operations to/from the SPIx_DR register.
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