32.3. Block Diagram
Figure 32-1. USART Block Diagram
GCLK
(internal)
XCK
BAUD
baud rate generator
/1 - /2 - /16
TX DATA
tx shift register
rx shift register
STATUS
status
RX DATA
rx buffer
TxD
RxD
32.4. Signal Description
Table 32-1. SERCOM USART Signals
Signal Name
Type
Description
PAD[3:0]
Digital I/O
General SERCOM pins
One signal can be mapped to one of several pins.
Related Links
I/O Multiplexing and Considerations
on page 27
32.5. Product Dependencies
In order to use this peripheral, other parts of the system must be configured correctly, as described below.
32.5.1. I/O Lines
Using the USART’s I/O lines requires the I/O pins to be configured using the I/O Pin Controller (PORT).
When the SERCOM is used in USART mode, the SERCOM controls the direction and value of the I/O
pins according to the table below. Both PORT control bits PINCFGn.PULLEN and PINCFGn.DRVSTR are
still effective. If the receiver or transmitter is disabled, these pins can be used for other purposes.
Table 32-2. USART Pin Configuration
Pin
Pin Configuration
TxD
Output
RxD
Input
XCK
Output or input
The combined configuration of PORT and the Transmit Data Pinout and Receive Data Pinout bit fields in
the Control A register (CTRLA.TXPO and CTRLA.RXPO, respectively) will define the physical position of
the USART signals in
.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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