AT91SAM7A1-AU Atmel, AT91SAM7A1-AU Datasheet - Page 275

• Manufacturer Part Number: AT91SAM7A1-AU
• Description: IC ARM7 MCU 32BIT ROMLESS144LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7A1-AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 40MHz
• Connectivity: CAN, EBI/EMI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 49
• Program Memory Type: ROMless
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 144-LQFP
• For Use With: AT91SAM7A1-EK - BOARD EVAL FOR AT91SAM7A1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

Figure 25-2. Data Frame
Figure 25-3. Standard Format
Figure 25-4. Extended Format
6048B–ATARM–29-Jun-06
Interframe
Space
SOF
SOF
11-bit Identifier (Base ID)
Arbitration
The data field can be of length zero.
Start Of Frame (Standard and Extended Format)
The Start of Frame (SOF) marks the beginning of data frames and remote frames. It consists
of a single dominant bit.
A node is only allowed to start transmission when the bus is idle. All nodes have to synchro-
nize to the leading edge caused by start of frame of the node starting transmission first.
Arbitration Field
The format of the arbitration field is different for standard format and extended format frames.
In standard format, the arbitration field consists of the 11-bit identifier and the RTR bit. The
identifier bits are denoted ID[10:0].
In extended format, the arbitration field consists of the 29-bit identifier, the SRR bit, the IDE bit,
and the RTR bit. The identifier bits are denoted ID[28:0]. The base identifier ID[10:0] are sent
first, and extended identifier ID[28:11] later.
In order to distinguish between standard format and extended format, the reserved bit r1 in
previous CAN specifications version 1.0-1.2 now is denoted as IDE bit.
The identifier’s length is 11 bits and corresponds to the base ID in extended format. These bits
are transmitted in the order from ID10 to ID0. The least significant bit is ID0. The 7 most signif-
icant bits ID[10:4] must not be all recessive.
In contrast to the standard format, the extended format consists of 29 bits. The format com-
prises two sections:
Field
• End Of Frame (EOF)
• Identifier - Standard Format
• Identifier - Extended Format
SOF
Control
Field
11-bit Identifier
Arbitration Field
SRR IDE
Arbitration Field
18-bit Identifier (Extended ID) RTR r1
Data Frame
RTR IDE
Field
Data
Control Field
r0
CRC
Field
DLC
Control Field
r0
ACK
Field
Data Field
DLC
EOF
AT91SAM7A1
Data Field
Interframe Space
or Overload Frame
or Error Frame
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