SAM3N0A Atmel Corporation, SAM3N0A Datasheet - Page 555

• Manufacturer Part Number: SAM3N0A
• Manufacturer: Atmel Corporation

30.7.7.7
30.7.8
30.7.8.1
30.7.8.2
11011A–ATARM–04-Oct-10
11011A–ATARM–04-Oct-10
WRITE BUFFER
DATA 0
DATA N
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Test Modes
Normal Mode
Automatic Echo Mode
Receiver Timeout
(Peripheral) DMA
Controller
Because the receiver baudrate clock is active only during data transfers in SPI Mode, a receiver
timeout is impossible in this mode, whatever the Time-out value is (field TO) in the Time-out
Register (US_RTOR).
The USART can be programmed to operate in three different test modes. The internal loopback
capability allows on-board diagnostics. In the loopback mode the USART interface pins are dis-
connected or not and reconfigured for loopback internally or externally.
Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD
pin.
Figure 30-30. Normal Mode Configuration
Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it
is sent to the TXD pin, as shown in
the TXD pin. The RXD pin is still connected to the receiver input, thus the receiver remains
active.
Figure 30-31. Automatic Echo Mode Configuration
APB bus
TXRDY
LIN CONTROLLER
USART3
Transmitter
Transmitter
Receiver
Receiver
Figure
READ BUFFER
DATA N
DATA 0
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30-31. Programming the transmitter has no effect on
(Peripheral) DMA
Controller
RXD
TXD
RXD
TXD
APB bus
RXRDY
NACT = SUBSCRIBE
LIN CONTROLLER
SAM3N
SAM3N
USART3
555
555