AT91SAM9G45-EKES Atmel, AT91SAM9G45-EKES Datasheet - Page 592

• Manufacturer Part Number: AT91SAM9G45-EKES
• Description: KIT EVAL FOR AT91SAM9G45
• Manufacturer: Atmel
• Series: AT91SAM Smart ARMr
• Type: MCUr

Specifications of AT91SAM9G45-EKES

• Contents: Board
• Processor To Be Evaluated: SAM9G45
• Data Bus Width: 32 bit
• Interface Type: I2C, SPI, UART
• Maximum Operating Temperature: + 50 C
• Minimum Operating Temperature: - 10 C
• Operating Supply Voltage: 1.8 V to 3.3 V
• For Use With/related Products: AT91SAM9G45
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4626953

33.7.6
Figure 33-36. Typical Connection to a RS485 Bus
Figure 33-37. Example of RTS Drive with Timeguard
33.7.7
6438F–ATARM–21-Jun-10
RS485 Mode
SPI Mode
The USART features the RS485 mode to enable line driver control. While operating in RS485
mode, the USART behaves as though in asynchronous or synchronous mode and configuration
of all the parameters is possible. The difference is that the RTS pin is driven high when the
transmitter is operating. The behavior of the RTS pin is controlled by the TXEMPTY bit. A typical
connection of the USART to a RS485 bus is shown in
The USART is set in RS485 mode by programming the USART_MODE field in the Mode Regis-
ter (US_MR) to the value 0x1.
The RTS pin is at a level inverse to the TXEMPTY bit. Significantly, the RTS pin remains high
when a timeguard is programmed so that the line can remain driven after the last character com-
pletion.
when the timeguard is enabled.
The Serial Peripheral Interface (SPI) Mode is a synchronous serial data link that provides com-
munication with external devices in Master or Slave Mode. It also enables communication
between processors if an external processor is connected to the system.
Baud Rate
TXEMPTY
US_THR
TXRDY
Clock
Write
TXD
RTS
Figure 33-37
USART
Start
Bit
D0
RXD
TXD
RTS
gives an example of the RTS waveform during a character transmission
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
Differential
TG = 4
Bus
Figure
33-36.
AT91SAM9G45
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