Datasheet

Clear
URXS
Clear
τ
S
SYNC
Valid Start Bit
Receiver Collects Character
URXSE
From URXD
PE
FE
BRK
URXEIE
URXWIE
RXWAKE
Erroneous Character Rejection
Non-Address Character Rejection
Character Received
or
Break Detected
URXIFGx
URXIEx
Interrupt Service
Requested
SWRST
PUC
UxRXBUF Read
URXSE
IRQA
S
Clear
UTXIEx
Clear
D
Character Moved From
Buffer to Shift Register
Interrupt Service Requested
SWRST
Data written to UxTXBUF
Q
UTXIFGx
IRQA
V
CC
PUC or SWRST
Q
Set
www.ti.com USART Operation: UART Mode
18.2.7 USART Interrupts
The USART has one interrupt vector for transmission and one interrupt vector for reception.
18.2.7.1 USART Transmit Interrupt Operation
The UTXIFGx interrupt flag is set by the transmitter to indicate that UxTXBUF is ready to accept another
character. An interrupt request is generated if UTXIEx and GIE are also set. UTXIFGx is automatically
reset if the interrupt request is serviced or if a character is written to UxTXBUF.
UTXIFGx is set after a PUC or when SWRST = 1. UTXIEx is reset after a PUC or when SWRST = 1. The
operation is shown is Figure 18-10.
Figure 18-10. Transmit Interrupt Operation
18.2.7.2 USART Receive Interrupt Operation
The URXIFGx interrupt flag is set each time a character is received and loaded into UxRXBUF. An
interrupt request is generated if URXIEx and GIE are also set. URXIFGx and URXIEx are reset by a
system reset PUC signal or when SWRST = 1. URXIFGx is automatically reset if the pending interrupt is
served (when URXSE = 0) or when UxRXBUF is read. The operation is shown in Figure 18-11.
Figure 18-11. Receive Interrupt Operation
487
SLAU144J–December 2004–Revised July 2013 USART Peripheral Interface, UART Mode
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