ML51/ML54/ML56
Sep. 01, 2020
Page
294
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Rev 2.00
ML
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54
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TECHNI
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ML51/M
L54
/M
L56
Series
Tec
hnical Reference
Manual
XLTCON
– XLT Clock Control (TA Protected)
Register
SFR Address
Reset Value
XLTCON
85H, Page 1, TA protected
0111_0111b
7
6
5
4
3
2
1
0
HSCH
HXSG[6:4]
-
-
LXSG[1:0]
R/W
R/W
-
-
R/W
Bit
Name
Description
[7]
HSCH
HXT Schmitt Trigger Select
0 = disable
1 = enable
[6:4]
HXSG[6:4]
HXT Gain Value Select
000 = L0 mode (smallest value)
001 = L1 mode
010 = L2 mode
011 = L3 mode
100 = L4 mode
101 = L5 mode
110 = L6 mode
111 = L7 mode (largest value)
[3:2]
-
Reserved
[1:0]
LXSG[1:0]
LXT Gain Value Select
00 = L0 mode (smallest value)
01 = L1 mode
10 = L2 mode
11 = L3 mode (largest value)
System Clock Switching
6.2.1.4
The ML51/ML54/ML56 Series supports clock source switching on-the-fly by controlling CKSWT and
CKEN registers via software. It provides a wide flexibility in application. Note that these SFR are
writing TA protected for precaution. With this clock source control, the clock source can be switched
between the external clock source and the internal oscillator, even between the high and low-speed
internal oscillator. However, during clock source switching, the device requires some amount of warm-
up period for an original disabled clock source. Therefore, use should follow steps below to ensure a
complete clock source switching. User can enable the target clock source by writing proper value into
CKEN register, wait for the clock source stable by polling its status bit in CKSWT register, and switch
to the target clock source by changing OSC[2:0] (CKSWT[2:0]). After these step, the clock source
switching is successful and then user can also disable the original clock source if power consumption