SAM3N4B Atmel Corporation, SAM3N4B Datasheet - Page 544

• Manufacturer Part Number: SAM3N4B
• Manufacturer: Atmel Corporation

Specifications of SAM3N4B

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 48 MHz
• Cpu: Cortex-M3
• # Of Touch Channels: 32
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 79
• Ext Interrupts: 79
• Quadrature Decoder Channels: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 3
• Twi (i2c): 2
• Uart: 4
• Ssc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 10
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Dac Channels: 1
• Dac Resolution (bits): 10
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 24
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 1.62 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 6
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

30.7.4
30.7.4.1
30.7.4.2
544
544
SAM3N
SAM3N
ISO7816 Mode
ISO7816 Mode Overview
Protocol T = 0
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.
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.
The ISO7816 is a half duplex communication on only one bidirectional line. The baud rate is
determined by a division of the clock provided to the remote device (see
on page
The USART connects to a smart card as shown in
tional and the Baud 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 con-
sidered as the master of the communication as it generates the clock.
Figure 30-20. 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 pro-
grammed 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 normal or inverse mode. Refer to
“USART Mode Register” on page 561
The USART cannot operate concurrently in both receiver and transmitter modes as the commu-
nication is unidirectional at a time. It has to be configured according to the required mode by
enabling or disabling either the receiver or the transmitter as desired. Enabling both the receiver
and the transmitter at the same time in ISO7816 mode may lead to unpredictable results.
The ISO7816 specification defines an inverse transmission format. Data bits of the character
must be transmitted on the I/O line at their negative value. The USART does not support this for-
mat and the user has to perform an exclusive OR on the data before writing it in the Transmit
Holding Register (US_THR) or after reading it in the Receive Holding Register (US_RHR).
In T = 0 protocol, a character is made up of one start bit, eight data bits, one parity bit and one
guard time, which lasts two bit times. The transmitter shifts out the bits and does not drive the
I/O line during the guard time.
If no parity error is detected, the I/O line remains to 1 during the guard time and the transmitter
can continue with the transmission of the next character, as shown in
529).
USART
SCK
TXD
and
“PAR: Parity Type” on page
Figure
CLK
I/O
30-20. The TXD line becomes bidirec-
Smart
Card
Figure
562.
“Baud Rate Generator”
11011A–ATARM–04-Oct-10
11011A–ATARM–04-Oct-10
30-21.