Datasheet

575
SAM9G45 [DATASHEET]
Atmel-6438O-ATARM-SAM9G45-Datasheet_08-Dec-15
32.6 Product Dependencies
32.6.1 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.
32.6.2 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.
Table 32-3. I/O Lines
Instance Signal I/O Line Peripheral
USART0 CTS0 PB15 B
USART0 RTS0 PB17 B
USART0 RXD0 PB18 A
USART0 SCK0 PB16 B
USART0 TXD0 PB19 A
USART1 CTS1 PD17 A
USART1 RTS1 PD16 A
USART1 RXD1 PB5 A
USART1 SCK1 PD29 B
USART1 TXD1 PB4 A
USART2 CTS2 PC11 B
USART2 RTS2 PC9 B
USART2 RXD2 PB7 A
USART2 SCK2 PD30 B
USART2 TXD2 PB6 A
USART3 CTS3 PA24 B
USART3 RTS3 PA23 B
USART3 RXD3 PB9 A
USART3 SCK3 PA22 B
USART3 TXD3 PB8 A