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NUC126
Aug. 08, 2018
Page
622
of 943
Rev 1.03
NUC12
6 S
E
RI
E
S
T
E
CH
NI
CA
L R
E
F
E
RE
NCE
MA
NUA
L
I
2
S Clock Divider Control Register (SPIx_I2SCLK)
Register
Offset
R/W
Description
Reset Value
SPIx_I2SCLK
0x64
R/W
I
2
S Clock Divider Control Register
0x0000_0000
Note:
Not supported in SPI mode.
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
BCLKDIV
15
14
13
12
11
10
9
8
BCLKDIV
7
6
5
4
3
2
1
0
Reserved
MCLKDIV
Bits
Description
[31:17]
Reserved
Reserved.
[16:8]
BCLKDIV
Bit Clock Divider
The I
2
S controller will generate bit clock in Master mode. The clock frequency of bit clock ,
f
BCLK
, is determined by the following expression:
)
1
BCLKDIV
(
2
_
_
2
f
f
src
clock
s
i
BCLK
where
f
src
clock
s
i
_
_
2
is the frequency of I
2
S peripheral clock source, which is defined in the
clock control register CLK_CLKSEL2.
In I
2
S Slave mode, this field is used to define the frequency of peripheral clock and it’s
determined by
1
2
BCLKDIV
_
_
2
f
src
clock
s
i
.
The peripheral clock frequency in I
2
S Slave mode must be equal to or faster than 6 times
of input bit clock.
[7:6]
Reserved
Reserved.
[5:0]
MCLKDIV
Master Clock Divider
If MCLKEN is set to 1, I
2
S controller will generate master clock for external audio devices.
The frequency of master clock, f
MCLK
, is determined by the following expressions:
If MCLKDIV >= 1,.
MCLKDIV
2
_
_
2
f
f
src
clock
s
i
MCLK
If MCLKDIV = 0,.
f
f
src
clock
s
i
MCLK
_
_
2
where
f
src
clock
s
i
_
_
2
is the frequency of I
2
S peripheral clock source, which is defined in the
clock control register CLK_CLKSEL2. In general, the master clock rate is 256 times
sampling clock rate.