
M451
May. 4, 2018
Page
592
of
1006
Rev.2.08
M4
51
S
E
RI
E
S
T
E
CH
NICA
L RE
F
E
R
E
NC
E
M
A
NU
A
L
11
10
01
00
PLL FOUT
1/(
)
UART0_CLK
UART3_CLK
UART1_CLK
UART2_CLK
22.1184 MHz
HIRC
4~24 MHz
HXT
UARTSEL(CLK_CLKSEL1[25:24])
UART0CKEN(CLK_APBCLK0[16])
1
UARTDIV(CLK_CLKDIV0[11:8])
UART1CKEN(CLK_APBCLK0[17])
UART2CKEN(CLK_APBCLK0[18])
UART3CKEN(CLK_APBCLK0[19])
32.768 kHz
LXT
Note: Before clock switching, both the pre-selected and newly selected clock sources must be turned on and stable.
Figure 6.13-1 UART Clock Control Diagram
UART_CLK
IrDA Encode
TX Shift Register
TX_FIFO
RX_FIFO
RX Shift Register
IrDA Decode
Baud Out
Baud Out
Status & Control
Status & Control
Baud Rate
Generator
FIFO & Line
Control and Status
Register
MODEM
Control and Status
Register
Interrupt
Control
& status
UART Interrupt
APB_BUS
Auto Baud Rate
UART_nRTS
UART_TXD
UART_nCTS
UART_RXD