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M0A21/M0A23 Series
May 06, 2022
Page
427
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
start bit is about 91.129us. It means that the value of STCOMP (UART_DWKCOMP[15:0]) can be set
as 0x1116.
Note2:
The
value
of
BRD
(UART_BAUD[15:0])
should
be
greater
than
STCOMP
(UART_DWKCOMP[15:0]).
Power-down mode
UART_CLK
UART_RXD
DATWKF
UART_CLK stable count
CPU run
start
HCLK
stable count
Note1:
Stable count means HCLK source recovery stable count.
Note2:
UART_CLK stable count means UART clock source recovery stable count.
Figure 6.11-7 UART Data Wake-up
Received Data FIFO Reached Threshold Wake-up
The received data FIFO threshold reached wake-up function is enabled by setting WKRFRTEN
(UART_WKCTL[2]). In Power-down mode, when the number of received data in RX FIFO reaches the
threshold value RFITL (UART_FIFO[7:4]), it can wake-up the system. If the WKRFRTEN
(UART_WKCTL[2]) is enabled, the number of received data in RX FIFO reaches the threshold value
RFITL (UART_FIFO[7:4]) cause the received data FIFO reached threshold wake-up flag RFRTWKF
(UART_WKSTS[2]) is generated. The Received Data FIFO reached threshold wake-up is shown in
Figure 6.11-8.
Note:
The UART controller clock source should be selected as LXT in Power-down mode to receive
data.
Power-down mode
HCLK
RFRTWKF
Start
DATA0
DATA1
RX FIFO number reached RFITL
UART_RXD
DATAx
stable
count
Note:
Stable count means HCLK source recovery stable count.
Figure 6.11-8 UART Received Data FIFO Reached Threshold Wake-up
RS-485 Address Match (AAD Mode) Wake-up
The RS-485 address match wake-up function is enabled by setting WKRFRTEN (UART_WKCTL[2])
and WKRS485EN (UART_WKCTL[3]). This function is used for RS-485 Auto Address Detection (AAD)
mode in RS-485 function mode and ADDRDEN (UART_ALTCTL[15]) is set to 1. In Power-down mode,
when an address byte is detected and matches the ADDRMV (UART_ALTCTL[31:24]) or the number
of received data in RX FIFO reaches the threshold value RFITL (UART_FIFO[7:4]), it can wake-up the
system. If the WKRS485EN (UART_WKCTL[3]) is enabled, when an address byte is detected and
matches the ADDRMV (UART_ALTCTL[31:24]) that cause the RS485 address match (AAD mode)
wake-up flag RS485WKF (UART_WKSTS[3]) is generated. The RS-485 Address Match (AAD mode)
wake-up is shown in Figure 6.11-9.
Note:
The UART controller clock source should be selected as LXT in Power-down mode to receive
data.