Datasheet

515
SAM9263 [DATASHEET]
Atmel-6249N-ATARM-SAM9263-Datasheet_14-Mar-16
33.5 Product Dependencies
33.5.1 I/O Lines
The pins used for interfacing the USART may be multiplexed with the PIO lines. The programmer must first
program the PIO controller to assign the desired USART pins to their peripheral function. If I/O lines of the USART
are not used by the application, they can be used for other purposes by the PIO Controller.
To prevent the TXD line from falling when the USART is disabled, the use of an internal pull up is mandatory. If the
hardware handshaking feature is used, the internal pull up on TXD must also be enabled.
33.5.2 Power Management
The USART is not continuously clocked. The programmer must first enable the USART Clock in the Power
Management Controller (PMC) before using the USART. However, if the application does not require USART
operations, the USART clock can be stopped when not needed and be restarted later. In this case, the USART will
resume its operations where it left off.
Configuring the USART does not require the USART clock to be enabled.
33.5.3 Interrupt
The USART interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using
the USART interrupt requires the AIC to be programmed first. Note that it is not recommended to use the USART
interrupt line in edge sensitive mode.