Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Hoja De Datos

 692

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

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 or Modem mode is used, the internal pull up on TXD must also be enabled.

All the pins of the modems may or may not be implemented on the USART. Only USART

1

 fully equipped with all the

modem signals. On USARTs not equipped with the corresponding pin, the associated control bits and statuses have no
effect on the behavior of the USART.

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. 

USART0

CTS0

PA8

A

USART0

RTS0

PA7

A

USART0

RXD0

PA5

A

USART0

SCK0

PA2

B

USART0

TXD0

PA6

A

USART1

CTS1

PA25

A

USART1

DCD1

PA26

A

USART1

DSR1

PA28

A

USART1

DTR1

PA27

A

USART1

RI1

PA29

A

USART1

RTS1

PA24

A

USART1

RXD1

PA21

A

USART1

SCK1

PA23

A

USART1

TXD1

PA22

A