AT91SAM9XE256-CU Atmel, AT91SAM9XE256-CU Datasheet - Page 512

• Manufacturer Part Number: AT91SAM9XE256-CU
• Description: MCU ARM9 256K FLASH 217-BGA
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM9XE256-CU

• Core Processor: ARM9
• Core Size: 16/32-Bit
• Speed: 180MHz
• Connectivity: EBI/EMI, Ethernet, I²C, MMC, SPI, SSC, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 96
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 56K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 217-LFBGA
• Processor Series: AT91SAMx
• Core: ARM926EJ-S
• Data Bus Width: 32 bit
• Data Ram Size: 32 KB
• Interface Type: 2-Wire, EBI, I2S, SPI, USART
• Maximum Clock Frequency: 180 MHz
• Number Of Programmable I/os: 96
• Number Of Timers: 6
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JTRACE-ARM-2M, KSK-AT91SAM9XE-PL, MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: AT91SAM-ICE, AT91-ISP, AT91SAM9XE-EK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 4 Channel
• Package: 217LFBGA
• Device Core: ARM926EJ-S
• Family Name: 91S
• Maximum Speed: 180 MHz
• Operating Supply Voltage: 1.8|2.5|3.3 V
• For Use With: AT91SAM9XE-EK - KIT EVAL FOR AT91SAM9XEAT91SAM-ICE - EMULATOR FOR AT91 ARM7/ARM9
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

34.6.3.10
34.6.3.11
6254C–ATARM–22-Jan-10
Multidrop Mode
Transmitter Timeguard
Figure 34-22. Parity Error
If the PAR field in the Mode Register (US_MR) is programmed to the value 0x6 or 0x07, the
USART runs in Multidrop Mode. This mode differentiates the data characters and the address
characters. Data is transmitted with the parity bit at 0 and addresses are transmitted with the
parity bit at 1.
If the USART is configured in multidrop mode, the receiver sets the PARE parity error bit when
the parity bit is high and the transmitter is able to send a character with the parity bit high when
the Control Register is written with the SENDA bit at 1.
To handle parity error, the PARE bit is cleared when the Control Register is written with the bit
RSTSTA at 1.
The transmitter sends an address byte (parity bit set) when SENDA is written to US_CR. In this
case, the next byte written to US_THR is transmitted as an address. Any character written in
US_THR without having written the command SENDA is transmitted normally with the parity at
0.
The timeguard feature enables the USART interface with slow remote devices.
The timeguard function enables the transmitter to insert an idle state on the TXD line between
two characters. This idle state actually acts as a long stop bit.
The duration of the idle state is programmed in the TG field of the Transmitter Timeguard Regis-
ter (US_TTGR). When this field is programmed at zero no timeguard is generated. Otherwise,
the transmitter holds a high level on TXD after each transmitted byte during the number of bit
periods programmed in TG in addition to the number of stop bits.
As illustrated in
the programming of a timeguard. TXRDY rises only when the start bit of the next character is
sent, and thus remains at 0 during the timeguard transmission if a character has been written in
US_THR. TXEMPTY remains low until the timeguard transmission is completed as the time-
guard is part of the current character being transmitted.
Baud Rate
RXRDY
US_CR
PARE
Clock
Write
Figure
RXD
AT91SAM9XE128/256/512 Preliminary
34-23, the behavior of TXRDY and TXEMPTY status bits is modified by
Start
Bit
D0
D1
D2
D3
D4
D5
D6
D7
Parity
Bad
Bit
Stop
Bit
RSTSTA = 1
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