ISD94100 Series Technical Reference Manual
Sep 9, 2019
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Rev1.09
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Clock Source Select Control Register 3
(CLK_CLKSEL3)
Before clock switching, the related clock sources (pre-select and new-select) must be turned on.
Register
Offset
R/W Description
Reset Value
CLK_CLKSEL3
0x1C
R/W Clock Source Select Control Register 3
0x0000_0000
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
I2S0SEL
15
14
13
12
11
10
9
8
Reserved
RTCSEL
7
6
5
4
3
2
1
0
Reserved
Bits
Description
[31:18]
Reserved
Reserved. Any values read should be ignored. When writing to this field always write with
reset value.
[17:16]
I2S0SEL
I
2
S0 Clock Source Selection
00 = Clock source from external high speed crystal oscillator (HXT).
01 = Clock source from PLL clock.
10 = Clock source from PCLK0.
11 = Clock source from internal high speed RC oscillator (HIRC).
[15:9]
Reserved
Reserved. Any values read should be ignored. When writing to this field always write with
reset value.
[8]
RTCSEL
RTC Clock Source Selection
0 = Clock source from external low speed crystal oscillator (LXT).
1 = Clock source from internal low speed RC oscillator (LIRC).
[7:0]
Reserved
Reserved. Any values read should be ignored. When writing to this field always write with
reset value.
