719
SAM4CP [DATASHEET]
43051E–ATPL–08/14
35.4
Product Dependencies
35.4.1 I/O Lines
The UART pins are multiplexed with PIO lines. The user must first configure the corresponding PIO Controller to enable
I/O line operations of the UART.
35.4.2 Power Management
The UART clock can be controlled through the Power Management Controller (PMC). In this case, the user must first
configure the PMC to enable the UART clock. Usually, the peripheral identifier used for this purpose is 1.
35.4.3 Interrupt Source
The UART interrupt line is connected to one of the interrupt sources of the Interrupt Controller. Interrupt handling requires
programming of the Interrupt Controller before configuring the UART.
35.4.4 Optical Interface
The UART optical interface requires configuration of the PMC to generate 4096 kHz or 8192 kHz on the PLLA prior to
any transfer.
35.5
Functional Description
The UART operates in asynchronous mode only and supports only 8-bit character handling (with parity). It has no clock
pin.
The UART is made up of a receiver and a transmitter that operate independently, and a common baud rate generator.
Receiver timeout and transmitter time guard are not implemented. However, all the implemented features are compatible
with those of a standard USART.
35.5.1 Baud Rate Generator
The baud rate generator provides the bit period clock named baud rate clock to both the receiver and the transmitter.
The baud rate clock is the peripheral clock divided by 16 times the clock divisor (CD) value written in the Baud Rate
Generator Register (UART_BRGR). If UART_BRGR is set to 0, the baud rate clock is disabled and the UART remains
inactive. The maximum allowable baud rate is peripheral clock divided by 16. The minimum allowable baud rate is
peripheral clock divided by (16 x 65536).
Table 35-2.
I/O Lines
Instance
Signal
I/O Line
Peripheral
UART0
URXD0
PB4
A
UART0
UTXD0
PB5
A
UART1
URXD1
PC1
A
UART1
UTXD1
PC0
A
Baud Rate
16
CD
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