CS Registers
398
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Clock System (CS)
6.3.4 CSCTL2 Register (offset = 0Ch) [reset = 0001_0003h]
Clock System Control 2 Register
Figure 6-8. CSCTL2 Register
31
30
29
28
27
26
25
24
Reserved
HFXTBYPASS
HFXT_EN
r-0
r-0
r-0
r-0
r-0
r-0
rw-0
rw-0
23
22
21
20
19
18
17
16
Reserved
HFXTFREQ
Reserved
Reserved
HFXTDRIVE
r-0
rw-0
rw-0
rw-0
r-0
rw-0
rw-0
rw-1
15
14
13
12
11
10
9
8
Reserved
LFXTBYPASS
LFXT_EN
r-0
r-0
r-0
r-0
r-0
r-0
rw-0
rw-0
7
6
5
4
3
2
1
0
Reserved
Reserved
LFXTDRIVE
rw-0
rw-0
rw-0
rw-0
rw-0
rw-0
rw-1
rw-1
Table 6-6. CSCTL2 Register Description
Bit
Field
Type
Reset
Description
31-26
Reserved
R
0h
Reserved. Always reads as 0.
25
HFXTBYPASS
RW
0h
HFXT bypass select.
0b = HFXT sourced by external crystal.
1b = HFXT sourced by external square wave.
24
HFXT_EN
RW
0h
Turns on the HFXT oscillator regardless if used as a clock resource.
0b = HFXT is on if it is used as a source for MCLK, HSMCLK , or SMCLK and is
selected via the port selection and not in bypass mode of operation.
1b = HFXT is on if HFXT is selected via the port selection and HFXT is not in
bypass mode of operation.
23
Reserved
R
0h
Reserved. Always reads as 0.
22-20
HFXTFREQ
RW
0h
HFXT frequency selection. These bits must be set to the appropriate value
based on the frequency of the crystal connected. These bits are don't care in the
HFXT bypass mode of operation.
000b = 1 MHz to 4 MHz
001b = >4 MHz to 8 MHz
010b = >8 MHz to 16 MHz
011b = >16 MHz to 24 MHz
100b = >24 MHz to 32 MHz
101b = >32 MHz to 40 MHz
110b = >40 MHz to 48 MHz
111b = Reserved for future use.
19
Reserved
R
0h
Reserved. Always reads as 0.
18-17
Reserved
RW
0h
Reserved.
16
HFXTDRIVE
RW
1h
HFXT oscillator drive selection. Reset value is 1h when HFXT available, and 0h
when HFXT not available. This bit is a don't care in the HFXT bypass mode of
operation.
0b = To be used for HFXTFREQ setting 000b
1b = To be used for HFXTFREQ settings 001b to 110b
15-10
Reserved
R
0h
Reserved. Always reads as 0.
9
LFXTBYPASS
RW
0h
LFXT bypass select.
0b = LFXT sourced by external crystal.
1b = LFXT sourced by external square wave.