SAM4L Datasheet, PDF (571/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
Table 24-1.
PIN
RXD
TXD
RTS
CTS
SPI Operating Mode
USART
RXD
TXD
RTS
CTS
SPI Slave
MOSI
MISO
–
CS
SPI Master
MISO
MOSI
CS
–
24.4 I/O Lines Description
Table 24-2.
Name
CLK
TXD
RXD
RI
DSR
DCD
DTR
CTS
RTS
I/O Lines Description
Description
Serial Clock
Transmit Serial Data
or Master Out Slave In (MOSI) in SPI master mode
or Master In Slave Out (MISO) in SPI slave mode
Receive Serial Data
or Master In Slave Out (MISO) in SPI master mode
or Master Out Slave In (MOSI) in SPI slave mode
Ring Indicator
Data Set Ready
Data Carrier Detect
Data Terminal Ready
Clear to Send
or Slave Select (NSS) in SPI slave mode
Request to Send
or Slave Select (NSS) in SPI master mode
Type
I/O
Output
Input
Input
Input
Input
Output
Input
Output
Active Level
Low
Low
Low
Low
Low
Low
24.5 Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
below.
24.5.1 I/O Lines
The USART pins may be multiplexed with the I/O Controller lines. The user must first configure
the I/O Controller to assign these pins to their peripheral functions. Unused I/O lines may be
used for other purposes.
To prevent the TXD line from falling when the USART is disabled, the use of an internal pull-up
is required. If the hardware handshaking feature or modem mode is used, the internal pull-up on
RTS must also be enabled.
All the pins of the modems may or may not be implemented on the USART. On USARTs not
equipped with the corresponding pins, the associated control bits and statuses have no effect on
the behavior of the USART.
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