Serial peripheral interface (SPI)
RM0090
902/1731
DocID018909 Rev 11
When the master clock is disabled (MCKOE bit cleared):
F
S
= I2SxCLK / [(16*2)*((2*ODD))] when the channel frame is 16-bit wide
F
S
= I2SxCLK / [(32*2)*((2*ODD))] when the channel frame is 32-bit wide
provides example precision values for different clock configurations.
Note:
Other configurations are possible that allow optimum clock precision.
Table 126. Audio frequency precision (for PLLM VCO = 1 MHz or 2 MHz)
(1)
Master
clock
Target f
S
(Hz)
Data
format
PLLI2SN
PLLI2SR
I2SDIV I2SODD
Real f
S
(Hz)
Error
Disabled
8000
16-bit
192
2
187
1
8000
0.0000%
32-bit
192
3
62
1
8000
0.0000%
16000
16-bit
192
3
62
1
16000
0.0000%
32-bit
256
2
62
1
16000
0.0000%
32000
16-bit
256
2
62
1
32000
0.0000%
32-bit
256
5
12
1
32000
0.0000%
48000
16-bit
192
5
12
1
48000
0.0000%
32-bit
384
5
12
1
48000
0.0000%
96000
16-bit
384
5
12
1
96000
0.0000%
32-bit
424
3
11
1
96014.49219
0.0151%
22050
16-bit
290
3
68
1
22049.87695
0.0006%
32-bit
302
2
53
1
22050.23438
0.0011%
44100
16-bit
302
2
53
1
44100.46875
0.0011%
32-bit
429
4
19
0
44099.50781
0.0011%
192000
16-bit
424
3
11
1
192028.9844
0.0151%
32-bit
258
3
3
1
191964.2813
0.0186%
Enabled
8000
don't care
256
5
12
1
8000
0.0000%
16000
don't care
213
2
13
0
16000.60059
0.0038%
32000
don't care
213
2
6
1
32001.20117
0.0038%
48000
don't care
258
3
3
1
47991.07031
0.0186%
96000
don't care
344
2
3
1
95982.14063
0.0186%
22050
don't care
429
4
9
1
22049.75391
0.0011%
44100
don't care
271
2
6
0
44108.07422
0.0183%
1. This table gives only example values for different clock configurations. Other configurations allowing optimum clock
precision are possible.