Taskit ARM9 Development kit with Linux Stamp9261 Standard Starterkit Stamp9261 (64F/64R) 542275 データシート
製品コード
542275
4.26. Synchronous / Asynchronous Serial Interfaces (USART)
Three USARTs and one UART are integrated into the SAM9261 processor.
The UART ("Debug" UART) is used as the Stamp9261’s standard input/output port. It supports only
the normal mode (RS232 mode).
the normal mode (RS232 mode).
A receive and a transmit DMA channel is assigned to each USART / UART.
a) USART Modes
Six different modes are implemented within the USARTs:
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Normal (standard RS232 mode)
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RS485
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Hardware Handshaking
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ISO7816 Protocol: T=0
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ISO7816 Protocol: T=1
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IrDA
•
RS485 Operating Mode
In this mode, the RTS pin is automatically driven high during transmit operations. If RTS is connected
to the "enable" line of the RS485 driver, the driver will thus be enabled only during transmit operations.
to the "enable" line of the RS485 driver, the driver will thus be enabled only during transmit operations.
•
Hardware Handshaking Operating Mode
The hardware handshaking feature enables an out-of-band flow control by automatic management of
the pins RTS and CTS. The receive DMA channel must be active for this mode. The RTS signal is
driven high if the receiver is disabled or if the DMA indicates a buffer full condition. As the RTS signal
is connected to the CTS line of the connected device, its transmitter is thus prevented from sending
any more characters.
the pins RTS and CTS. The receive DMA channel must be active for this mode. The RTS signal is
driven high if the receiver is disabled or if the DMA indicates a buffer full condition. As the RTS signal
is connected to the CTS line of the connected device, its transmitter is thus prevented from sending
any more characters.
•
Smart Card Operating Modes
The USARTs have an ISO7816-compatible mode which permits interfacing with smart cards and
Security Access Modules (SAM). Both T=0 and T=1 protocols of the ISO7816 specification are
supported.
Security Access Modules (SAM). Both T=0 and T=1 protocols of the ISO7816 specification are
supported.
•
IrDA Operating Mode
The USART features an infrared (IrDA) mode supplying half-duplex point-to-point wireless
communication. It includes the modulator and demodulator which allows a glueless connection to the
infrared transceivers.
communication. It includes the modulator and demodulator which allows a glueless connection to the
infrared transceivers.
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.
transfer speeds ranging from 2.4 kb/s to 115.2 kb/s.
b) Signals of the serial interfaces
All UARTs/USARTs have one receiver and one transmitter data line (full duplex). The UARTS #1 and
#2 also have two handshake lines – RTS and CTS – as well as a clock line (SCK) for the synchronous
protocols.
All UARTs/USARTs have one receiver and one transmitter data line (full duplex). The UARTS #1 and
#2 also have two handshake lines – RTS and CTS – as well as a clock line (SCK) for the synchronous
protocols.
The Debug UART only has receiver and transmitter data lines. The same is true for USART #0 - its
handshake lines are not externally available on the Stamp9261.
handshake lines are not externally available on the Stamp9261.
The RI, DTR, DSR and DCD lines of USART #1 designated in the pin description of the Stamp9261
are not really part of the USART unit of the SAM9261. They are rather implemented as standard digital
ports (PIO ports).
are not really part of the USART unit of the SAM9261. They are rather implemented as standard digital
ports (PIO ports).
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