
M0A21/M0A23 Series
May 06, 2022
Page
504
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
Power-down mode
CLK
USCIx_DAT0
(RXD)
WKF
stable count
CPU run
start
Note:
Stable count means HCLK source recovery stable count.
Figure 6.13-6 Incoming Data Wake-Up
(b) nCTS pin wake-up
When system is in power-down and both of the WKEN (UUART_WKCTL[0]) and CTSWKEN
(UUART_PROTCTL[10]) are set, the toggle of nCTS pin can wake-up the system. The nCTS wake-wp
is shown in Figure 6.13-7 and Figure 6.13-8.
Case 1 (nCTS transition from low to high):
Power-down mode
CLK
USCIx_CTL0
(nCTS)
stable count
CPU run
WKF
Note:
Stable count means HCLK source recovery stable count.
Figure 6.13-7 nCTS Wake-Up Case 1
Case 2 (nCTS transition from high to low):
Power-down mode
CLK
USCIx_CTL0
(nCTS)
stable count
CPU run
WKF
Note 1:
Stable count means HCLK source recovery stable count.
Figure 6.13-8 nCTS Wake-Up Case 2
Interrupt Events
The UART provided interrupt for protocol event and data transfer event. The description show below:
Protocol Interrupt Events
The following protocol-related events are generated in UART mode and can lead to a protocol interrupt.
Please note that the bits in register UUART_PROTSTS are not automatically cleared by hardware and
have to be cleared by software in order to monitor new incoming events.
Receiver Line Status
The protocol-related error FRMERR (UUART_PROTSTS[6]) or PARITYERR (UUART_PROTSTS[5])
are two flags that are assigned to each received data word in the corresponding receiver buffer status