Table 164. Audio-Frequency Precision Using Standard 8 Mhz Hse - ST STM32F446 Series Reference Manual

RM0390
The audio sampling frequency may be 192 KHz, 96 kHz, 48 kHz, 44.1 kHz, 32 kHz,
22.05 kHz, 16 kHz, 11.025 kHz or 8 kHz (or any other value within this range). In order to
reach the desired frequency, the linear divider needs to be programmed according to the
formulas below:
When the master clock is generated (MCKOE in the SPIx_I2SPR register is set):
f = I2SxCLK / [(16*2)*((2*I2SDIV)+ODD)*8)] when the channel frame is 16-bit wide
S
f = I2SxCLK / [(32*2)*((2*I2SDIV)+ODD)*4)] when the channel frame is 32-bit wide
S
When the master clock is disabled (MCKOE bit cleared):
f = I2SxCLK / [(16*2)*((2*I2SDIV)+ODD))] when the channel frame is 16-bit wide
S
f = I2SxCLK / [(32*2)*((2*I2SDIV)+ODD))] when the channel frame is 32-bit wide
S
Table 164
Note: Other configurations are possible that allow optimum clock precision.
SYSCLK
(MHz)
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
provides example precision values for different clock configurations.

Table 164. Audio-frequency precision using standard 8 MHz HSE

Data
I2SDIV
length
16 8
32 4
16 15
32 8
16 17
32 8
16 23
32 11
16 34
32 17
16 47
32 23
16 68
32 34
16 94
32 47
16 2
32 2
16 2
32 2
16 3
32 3
16 4
Serial peripheral interface/ inter-IC sound (SPI/I2S)
Target f
I2SODD MCLK
0 No
0 No
1 No
0 No
0 No
1 No
1 No
1 No
0 No
0 No
0 No
1 No
0 No
0 No
0 No
0 No
0 Yes
0 Yes
0 Yes
0 Yes
0 Yes
0 Yes
1 Yes
RM0390 Rev 4
S
Real f (KHz)
S
(Hz)
96000 93750
96000 93750
48000 48387.0968
48000 46875
44100 44117.647
44100 44117.647
32000 31914.8936
32000 32608.696
22050 22058.8235
22050 22058.8235
16000 15957.4468
16000 15957.447
11025 11029.4118
11025 11029.412
8000 7978.7234
8000 7978.7234
48000 46875
48000 46875
44100 46875
44100 46875
32000 31250
32000 31250
22050 20833.333
(1)
Error
2.3438%
2.3438%
0.8065%
2.3438%
0.0400%
0.0400%
0.2660%
1.9022%
0.0400%
0.0400%
0.2660%
0.2660%
0.0400%
0.0400%
0.2660%
0.2660%
2.3430%
2.3430%
6.2925%
6.2925%
2.3438%
2.3438%
5.5178%
879/1328
896