AT32F421
Series Reference Manual
2022.11.11
Page 165
Rev 2.02
13.3.7 I2S communication timings
I2S supports four different audio standards: Philips standard, the most significant byte (left-aligned) and
the least significant byte (right-aligned) standards, and the PCM standard.
respective timings.
Figure 13-19 Audio standard timings
CK
SD
L15
//
R15
//
0
//
WS
//
Left
channe l
Right
channe l
Philips
standard
SD
L15
//
L0
0
0
R0
//
0
WS
Left
channe l
Right
channe l
MSB standard
SD
WS
Left
channe l
Right
channe l
LSB standard
SD
D15
//
D0
WS
PCM standard long
frame
SD
WS
PCM standard
short frame
13CK
//
//
//
//
//
//
L0
R0
R15
0
L15
//
L0
0
R15
//
R0
0
D15
//
D0
0
1CK
16CK
16CK
16CK
13.3.8 Interrupts
Figure 13-20 I
2
S interrupts
RDBF
RDBFIE
TDBE
TDBEIE
ROERR
TUERR
ERRIE
I2S interrupt
13.3.9 IO pin control
The I
2
S needs three pins for transfer operation, namely, the SD, WS and CK. The MCLK pin is also
required if need to provide main clock for peripherals. The I
2
S shares some pins with the SPI,
described as follows:
SD: Serial data (mapped on the MOSI pin) for bidirectional data transmission and reception.
WS: Word select (mapped on the CS pin) for data control signal output in master mode, and
input in slave mode.
CK: Communication clock (mapped on the SCK pin) as clock signal output in master mode, and
input in slave mode.
MCLK: Master clock (mapped independently) is used to provide main clock for peripherals. The
clock frequency output is fixed 256x Fs (audio sampling frequency). Some MCLK and MISO pins
share the same GPIO map.