Datasheet

URXDx

URXS

Majority Vote Taken

URXDx

URXS

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USART Operation: UART Mode

18.2.7.4 Receive-Start Edge Detect Conditions

When URXSE = 1, glitch suppression prevents the USART from being accidentally started. Any low-level

on URXDx shorter than the deglitch time t

(approximately 300 ns) is ignored by the USART and no

interrupt request is generated (see Figure 18-12). See the device-specific data sheet for parameters.

Figure 18-12. Glitch Suppression, USART Receive Not Started

When a glitch is longer than t

or a valid start bit occurs on URXDx, the USART receive operation is

started and a majority vote is taken as shown in Figure 18-13. If the majority vote fails to detect a start bit,

the USART halts character reception.

If character reception is halted, an active BRCLK is not necessary. A time-out period longer than the

character receive duration can be used by software to indicate that a character was not received in the

expected time, and the software can disable BRCLK.

Figure 18-13. Glitch Suppression, USART Activated

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SLAU144J–December 2004–Revised July 2013 USART Peripheral Interface, UART Mode

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