Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK データシート
製品コード
AT91SAM9M10-G45-EK
495
SAM9M10 [DATASHEET]
6355F–ATARM–12-Mar-13
Figure 31-28.
Receiver Behavior when Operating with Hardware Handshaking
shows how the transmitter operates if hardware handshaking is enabled. The CTS pin disables the
transmitter. If a character is being processing, the transmitter is disabled only after the completion of the current
character and transmission of the next character happens as soon as the pin CTS falls.
character and transmission of the next character happens as soon as the pin CTS falls.
Figure 31-29.
Transmitter Behavior when Operating with Hardware Handshaking
31.7.4
ISO7816 Mode
The USART features an ISO7816-compatible operating mode. This mode permits interfacing with smart cards and
Security Access Modules (SAM) communicating through an ISO7816 link. Both T = 0 and T = 1 protocols defined
by the ISO7816 specification are supported.
Security Access Modules (SAM) communicating through an ISO7816 link. Both T = 0 and T = 1 protocols defined
by the ISO7816 specification are supported.
Setting the USART in ISO7816 mode is performed by writing the USART_MODE field in the Mode Register
(US_MR) to the value 0x4 for protocol T = 0 and to the value 0x5 for protocol T = 1.
(US_MR) to the value 0x4 for protocol T = 0 and to the value 0x5 for protocol T = 1.
31.7.4.1
ISO7816 Mode Overview
The ISO7816 is a half duplex communication on only one bidirectional line. The baud rate is determined by a divi-
sion of the clock provided to the remote device (see
sion of the clock provided to the remote device (see
).
The USART connects to a smart card as shown in
Rate Generator feeds the ISO7816 clock on the SCK pin. As the TXD pin becomes bidirectional, its output remains
driven by the output of the transmitter but only when the transmitter is active while its input is directed to the input
of the receiver. The USART is considered as the master of the communication as it generates the clock.
driven by the output of the transmitter but only when the transmitter is active while its input is directed to the input
of the receiver. The USART is considered as the master of the communication as it generates the clock.
Figure 31-30.
Connection of a Smart Card to the USART
When operating in ISO7816, either in T = 0 or T = 1 modes, the character format is fixed. The configuration is 8
data bits, even parity and 1 or 2 stop bits, regardless of the values programmed in the CHRL, MODE9, PAR and
CHMODE fields. MSBF can be used to transmit LSB or MSB first. Parity Bit (PAR) can be used to transmit in nor-
mal or inverse mode. Refer to
data bits, even parity and 1 or 2 stop bits, regardless of the values programmed in the CHRL, MODE9, PAR and
CHMODE fields. MSBF can be used to transmit LSB or MSB first. Parity Bit (PAR) can be used to transmit in nor-
mal or inverse mode. Refer to
.
The USART cannot operate concurrently in both receiver and transmitter modes as the communication is unidirec-
tional at a time. It has to be configured according to the required mode by enabling or disabling either the receiver
tional at a time. It has to be configured according to the required mode by enabling or disabling either the receiver
RTS
RXBUFF
Write
US_CR
RXEN = 1
RXD
RXDIS = 1
CTS
TXD
Smart
Card
SCK
CLK
TXD
I/O
USART