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M0A21/M0A23 Series
May 06, 2022
Page
418
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
011
010
001
000
4~24 MHz HXT
PLL FOUT
[2]
32.768kHz LXT
48MHz HIRC
UART0SEL (CLK_CLKSEL1[26:24])
UART0DIV (CLK_CLKDIV0[11:8])
UART0CKEN (CLK_APBCLK0[16]
UART0_CLK
1/(U1)
100
PCLK0
011
010
001
000
4~24 MHz HXT
PLL FOUT
[2]
32.768kHz LXT
48MHz HIRC
UART1SEL (CLK_CLKSEL1[30:28])
UART1DIV (CLK_CLKDIV0[15:12])
UART1CKEN (CLK_APBCLK0[17]
UART1_CLK
1/(U1)
100
PCLK1
101
38.4kHz LIRC
101
38.4kHz LIRC
Note1:
Before clock switching, both the pre-selected and newly selected clock sources must be turned on and stable.
Note2:
Without PLL function, the clock source will be fixed at PCLK0/1, the same as UARTxSEL=3'b100. Please refer to
section 4.3 NuMicro® M0A21/M0A23 Series Selection Guide for detailed information.
Figure 6.11-1 UART Clock Control Diagram