GD32F403xx User Manual
480
(DTLEN=00, CHLEN=1, CKPL=1)
I2S_CK
I2S_SD
16-bit data
MSB
I2S_WS
MSB
frame 1
frame 2
13 bits
16-bit 0
19.4.4.
I2S clock
Figure 19-51. Block diagram of I2S clock generator
8-bit
Configurable
Divider
I2SCLK
Frequency dividing ratio =
DIV * 2 + OF
DIV4
DIV2
1
0
CHLEN
0
1
MCKOEN
I2S_CK
I2S_MCK
MCKOEN
The block diagram of I2S clock generator is shown as
Figure 19-51. Block diagram of I2S
. The I2S interf ace clocks are configured by the DIV bits, the OF bit, the
MCKOEN bit in the SPI_I2SPSC register and the CHLEN bit in the SPI_I2SCTL register. The
I2S bitrate can be calculated by the f ormulas shown in
Table 19-7. I2S bitrate calculation
Table 19-7. I2S bitrate calculation formulas
MCKOEN
CHLEN
Formula
0
0
I2SCLK / (DIV * 2 + OF)
0
1
I2SCLK / (DIV * 2 + OF)
1
0
I2SCLK / (8 * (DIV * 2 + OF))
1
1
I2SCLK / (4 * (DIV * 2 + OF))
The relationship between audio sampling frequency (Fs) and I2S bitrate is defined by the
following formula:
Fs = I2S bitrate / (number of bits per channel * number of channels)
So, in order to get the desired audio sampling f requency, the clock generator needs to be
conf igured according to the f ormulas listed in
Table 19-8. Audio sampling frequency