Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet
Product codes
ATSAM4E-XPRO
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
910
If MAX_ITERATION does not equal zero, the USART repeats the character as many times as the value loaded in
MAX_ITERATION.
MAX_ITERATION.
When the USART repetition number reaches MAX_ITERATION, the ITERATION bit is set in US_CSR. If the
repetition of the character is acknowledged by the receiver, the repetitions are stopped and the iteration counter is
cleared.
repetition of the character is acknowledged by the receiver, the repetitions are stopped and the iteration counter is
cleared.
The ITERATION bit in US_CSR can be cleared by writing US_CR with the RSTIT bit to 1.
Disable Successive Receive NACK
The receiver can limit the number of successive NACKs sent back to the remote transmitter. This is programmed
by setting the bit DSNACK in the US_MR. The maximum number of NACKs transmitted is programmed in the
MAX_ITERATION field. As soon as MAX_ITERATION is reached, the character is considered as correct, an
acknowledge is sent on the line and the ITERATION bit in the US_CSR is set.
by setting the bit DSNACK in the US_MR. The maximum number of NACKs transmitted is programmed in the
MAX_ITERATION field. As soon as MAX_ITERATION is reached, the character is considered as correct, an
acknowledge is sent on the line and the ITERATION bit in the US_CSR is set.
38.7.4.3 Protocol T = 1
When operating in ISO7816 protocol T = 1, the transmission is similar to an asynchronous format with only one
stop bit. The parity is generated when transmitting and checked when receiving. Parity error detection sets the
PARE bit in the US_CSR.
stop bit. The parity is generated when transmitting and checked when receiving. Parity error detection sets the
PARE bit in the US_CSR.
38.7.5 IrDA Mode
The USART features an IrDA mode supplying half-duplex point-to-point wireless communication. It embeds the
modulator and demodulator which allows a glueless connection to the infrared transceivers, as shown in
modulator and demodulator which allows a glueless connection to the infrared transceivers, as shown in
. The modulator and demodulator are compliant with the IrDA specification version 1.1 and support data
transfer speeds ranging from 2.4 Kb/s to 115.2 Kb/s.
The IrDA mode is enabled by setting the USART_MODE field in US_MR to the value 0x8. The IrDA Filter register
(US_IF) is used to configure the demodulator filter. The USART transmitter and receiver operate in a normal
asynchronous mode and all parameters are accessible. Note that the modulator and the demodulator are
activated.
(US_IF) is used to configure the demodulator filter. The USART transmitter and receiver operate in a normal
asynchronous mode and all parameters are accessible. Note that the modulator and the demodulator are
activated.
Figure 38-33. Connection to IrDA Transceivers
The receiver and the transmitter must be enabled or disabled depending on the direction of the transmission to be
managed.
managed.
To receive IrDA signals, the following needs to be done:
Disable TX and Enable RX
Configure the TXD pin as PIO and set it as an output to 0 (to avoid LED emission). Disable the internal pull-
up (better for power consumption).
up (better for power consumption).
Receive data
IrDA
Transceivers
RXD
RX
TXD
TX
USART
Demodulator
Modulator
Receiver
Transmitter