USART Operation: UART Mode
14-9USART Peripheral Interface, UART Mode
14.2.4 USART Receive Enable
The receive enable bit, URXEx, enables or disables data reception on URXDx
as shown in Figure 145. Disabling the USART receiver stops the receive
operation following completion of any character currently being received or
immediately if no receive operation is active. The receive-data buffer,
UxRXBUF, contains the character moved from the RX shift register after the
character is received.
Figure 145. State Diagram of Receiver Enable
Idle State
(Receiver
Enabled)
Receive
Disable
Receiver
Collects
Character
URXEx = 0 No Valid Start Bit
Not Completed
URXEx = 1
URXEx = 0
URXEx = 1
Valid Start Bit Handle Interrupt
Conditions
Character
Received
URXEx = 1
URXEx = 0
Note: Re-Enabling the Receiver (Setting URXEx): UART Mode
When the receiver is disabled (URXEx = 0), re-enabling the receiver (URXEx
= 1) is asynchronous to any data stream that may be present on URXDx at
the time. Synchronization can be performed by testing for an idle line
condition before receiving a valid character (see URXWIE).