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The data to be received or sent is 0x62d8, which becomes
0x62D80000 after it is expanded to 32 bits, and it is necessary to
write 0x62D8 to SPI_DATA register or read out from SPI_DATA
register.
Figure 96 I2S Philips Protocol Waveform (extending from 16 bits to 32 bits)
High
bit
Right
channel
Left
channel
SPI_SD
Low bit
16-bit data
The remaining 16
bits are forced to 0
SPI_CK
SPI_WS
In the transmission process, the MSB should be written to the register
SPI_DATA, and when TXBEFLG flag bit is set to 1, new data can be written; if
there is corresponding interrupt, an interrupt can be generated.
In the receiving process, every time the MSB is received, the RXBNEFLG flag
bit will be set to 1; if there is corresponding interrupt, an interrupt can be
generated.
MSB alignment standard
In MSB standard, WS signal and the first data bit are generated at the same
time
In the transmission process, the data is changed on the falling edge of the clock
signal; in the receiving process, the data is read on the rising edge of the clock
signal.
Figure 97 MSB Alignment Standard Waveform (16/32-bit data)
Low
bit
High
bit
High
bit
Right channel
Left
channel
SPI_CK
SPI_WS
SPI_SD
16-bit/32-bit data