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M0A21/M0A23 Series
May 06, 2022
Page
183
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
111
011
010
001
HXT
LXT
HXT
HCLK
HIRC
000
1/2
1/2
1/2
CLK_CLKSEL0[5:3]
1
0
SysTick
WDT
CPU
011
001
LXT
HXT
LIRC
000
CLK_CLKSEL0[2:0]
SYST_CTRL[2]
CPUCLK
1/(1)
LIRC
11
10
CLK_CLKSEL1[1:0]
HCLK
1/2048
01
LXT
111
HIRC
WWDT
11
10
CLK_CLKSEL1[3:2]
HCLK
1/2048
/1,/2,/4,/8,/16
PDMA
FMC
CRC
PWM0
CAN0
TMR1
TMR0
UART0
LIRC
CLK_CLKSEL1[6:4]
/2
(CLK_CLKOCTL[3:0]+1)
0
1
DIV1EN
(CLK_CLKOCTL[5])
HCLK
SRAM
PCLK1
UART1
ADC
ACMP
USCI1
DAC
TMR2
TMR3
/1,/2,/4,/8,/16
010
001
000
LXT
HXT
101
100
HCLK
LIRC
HIRC
ADC
HXT
HIRC
1/( 1)
PCLK1
CLKSEL2[21:20]
11
10
00
HDIV
USCI0
WDT
UART0
HXT
CLK_CLKSEL1[26:24]
1/(U1)
000
010
011
100
101
LXT
HIRC
PCLK0/PCLK1
LIRC
PCLK0
GPIO
111
010
001
000
PCLK0
LXT
HXT
HIRC
CLK_CLKSEL1 [10:8]
CLK_CLKSEL1[14:12]
101
LIRC
011
TM0/TM1
TMR0
TMR1
111
010
001
000
PCLK1
LXT
HXT
HIRC
101
LIRC
011
TM2/TM3
TMR2
TMR3
CLK_CLKSEL1 [18:16]
CLK_CLKSEL1[22:20]
CKO
UART1
1/(U1)
CLK_CLKSEL1[30:28]
Figure 6.3-1 Clock Generator Global View Diagram
6.3.2
Clock Generator
The clock generator consists of 4 clock sources, which are listed below:
32.768 kHz external low speed crystal oscillator (LXT)
4~24 MHz external high speed crystal oscillator (HXT)
48 MHz internal high speed RC oscillator (HIRC)
38.4 kHz internal low speed RC oscillator (LIRC)