Datasheet

SAM9261 [DATASHEET]
Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16
432
31.3 Application Block Diagram
Figure 31-2. Application Block Diagram
31.4 I/O Lines Description
31.5 Product Dependencies
31.5.1 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.
31.5.2 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.
Smart
Card
Slot
USART
RS485
Drivers
Differential
Bus
IrDA
Transceivers
Field Bus
Driver
EMV
Driver
IrDA
Driver
IrLAP
RS232
Drivers
Serial
Port
Serial
Driver
PPP
Table 31-1. I/O Line Description
Name Description Type Active Level
SCK Serial Clock I/O
TXD Transmit Serial Data I/O
RXD Receive Serial Data Input
CTS Clear to Send Input Low
RTS Request to Send Output Low