GD32W51x User Manual
169
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11111: CK_HXTAL / 32
15:13
APB2PSC[2:0]
APB2 prescaler selection
Set and reset by softw are to control the APB2 clock division ratio.
0xx: Reserved
100: (CK_AHB / 2) selected
101: (CK_AHB / 4) selected
110: (CK_AHB / 8) selected
111: (CK_AHB / 16) selected
12:10
APB1PSC[2:0]
APB1 prescaler selection
Set and reset by softw are to control the APB1 clock division ratio.
0xx: Reserved
100: Reserved
101: (CK_AHB / 4) selected
110: (CK_AHB / 8) selected
111: (CK_AHB / 16) selected
9:8
Reserved
Must be kept at reset value.
7:4
AHBPSC[3:0]
AHB prescaler selection
Set and reset by softw are to control the AHB clock division ratio
0xxx: CK_SYS selected
1000: (CK_SYS / 2) selected
1001: (CK_SYS / 4) selected
1010: (CK_SYS / 8) selected
1011: (CK_SYS / 16) selected
1100: (CK_SYS / 64) selected
1101: (CK_SYS / 128) selected
1110: (CK_SYS / 256) selected
1111: (CK_SYS / 512) selected
3:2
SCSS[1:0]
System clock sw itch status
Set and reset by hardw are to indicate the clock source of system clock.
00: select CK_IRC16M as the CK_SYS source
01: select CK_HXTAL as the CK_SYS source
10: select CK_PLLP as the CK_SYS source
11: select CK_PLLDIG as the CK_SYS source
1:0
SCS[1:0]
System clock sw itch
Set by softw are to select the CK_SYS source. Because the change of CK_SYS has
inherent latency, softw are should read SCSS to confirm w hether the sw itching is
complete or not. The sw itch w ill be forced to IRC16M w hen leaving Deep-sleep and
Standby mode or HXTAL failure is detected by HXTAL clock monitor w hen HXTA L
is selected directly or indirectly as the clock source of CK_SYS
00: select CK_IRC16M as the CK_SYS source