AT32F425
Series Reference Manual
2022.03.30
Page 174
Ver 2.01
Programmable channel bits (16 bit, 32 bit)
Programmable audio protocol
─
I
2
S Philips standard
─
MSB-aligned standard (left-aligned)
─
LSB-aligned standard (right-aligned)
─
PCM standard (long or short frame)
I
2
S full-duplex
DMA transfer
Main peripheral clock with a fixed frequence of 256x Fs (audio sampling frequency)
13.3.2 I
2
S full-duplex
Two SPIs can be combined to support I
2
S full-duplex mode through the SCFG_CFG2[31:30] bit in
the SCFG register. Of the three SPIs, the SPI1 or SPI2 can be configured as full-duplex master,
while the SPI2 or SPI3 can be set as full-duplex slave, which is selected through the
SCFG_CFG2[31:30] bit in the SCFG register. Once selected, the IO remap relations of the master
remains unchanged, and the SCK and WS of the slave are connected to the SCK and WS of the
master internally, with the SD line of the slave remapped onto the I2Sext_SD. The slave’s original
IO remap relations become invalid, releasing the corresponding IOs.
Figure 13-17 I
2
S full-duplex structure
I
2
S master
(SPI1/SPI2)
I
2
S slave (SPI2/SPI3)
I2S1_SCK/
I2S2_SCK
I2S1_WS/
I2S2_WS
SPI1_MOSI/I2S1_SD(in/out)/
SPI2_MOSI/I2S2_SD(in/out)
I2Sext_SD(in/out)
I
2
S full-duplex master side:
It supports master or slave mode. It can programmed as a receiver or transmitter.
I2Sx_WS takes part in communication for actual WS signal interaction
I2Sx_SCK takes part in communication for actual clock signal interaction
I2Sx_SD takes part in communication for data and information interacton of the master side
I
2
S full-duplex slave side
It supports slave mode only. It can be programmed as a transmitter or receiver.
I2Sy_WS does not take part in communication, releasing the corresponding IOs
I2Sy_SCK does not take part in communication, releasing the corresponding IOs
I2Sy_SD does not take part in communication, releasing the corresponding IOs
I2Sext_SD takes part in communication for data and information interacton of the slave side
Note: x can be either 1 or 2, where as y can be either 2 or 3.
13.3.3 Operating mode selector
The SPI, used as I
2
S selector, offers multiple operating modes for selection, namely, slave device
transmission, slave device reception, master device transmission and master device reception. This is
done by software configuration.
Slave device transmission:
Set the I2SMSEL bit, and OPERSEL[1:0] =00, the I
2
S will work in slave device transmission mode.