AT90CAN64 Atmel Corporation, AT90CAN64 Datasheet - Page 236

• Manufacturer Part Number: AT90CAN64
• Manufacturer: Atmel Corporation

Specifications of AT90CAN64

• Flash (kbytes): 64 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• Can: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 4
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

19.2.2.2
Figure 19-2. CAN Extended Frames
19.2.2.3
19.2.3
19.2.3.1
236
Interframe
Interframe
Bus Idle
Bus Idle
Data Frame
Remote Frame
Space
Space
AT90CAN32/64/128
CAN Bit Timing
SOF
SOF
SOF
SOF
CAN Extended Frame
Format Co-existence
Bit Construction
11-bit base identifier
11-bit base identifier
IDT28..18
IDT28..18
A message in the CAN extended frame format is likely the same as a message in CAN standard
frame format. The difference is the length of the identifier used. The identifier is made up of the
existing 11-bit identifier (base identifier) and an 18-bit extension (identifier extension). The dis-
tinction between CAN standard frame format and CAN extended frame format is made by using
the IDE bit which is transmitted as dominant in case of a frame in CAN standard frame format,
and transmitted as recessive in the other case.
As the two formats have to co-exist on one bus, it is laid down which message has higher priority
on the bus in the case of bus access collision with different formats and the same identifier /
base identifier: The message in CAN standard frame format always has priority over the mes-
sage in extended format.
There are three different types of CAN modules available:
To ensure correct sampling up to the last bit, a CAN node needs to re-synchronize throughout
the entire frame. This is done at the beginning of each message with the falling edge SOF and
on each recessive to dominant edge.
One CAN bit time is specified as four non-overlapping time segments. Each segment is con-
structed from an integer multiple of the Time Quantum. The Time Quantum or TQ is the smallest
discrete timing resolution used by a CAN node.
SRR IDE
SRR IDE
Arbitration
Arbitration
– 2.0A - Considers 29 bit ID as an error
– 2.0B Passive - Ignores 29 bit ID messages
– 2.0B Active - Handles both 11 and 29 bit ID Messages
Field
Field
18-bit identifier extension
18-bit identifier extension
ID17..0
ID17..0
RTR
RTR
r1
r1
r0
r0
Control
Control
Field
Field
4-bit DLC
4-bit DLC
DLC4..0
DLC4..0
15-bit CRC
CRC
Field
0 - 8 bytes
Data
Field
CRC
del.
ACK
Field
ACK
ACK
del.
15-bit CRC
End of
Frame
7 bits
CRC
Field
CRC
Intermission
del.
3 bits
ACK
Field
ACK
Interframe
ACK
Space
del.
(Indefinite)
Bus Idle
End of
Frame
7 bits
7679H–CAN–08/08
Intermission
3 bits
Interframe
Space
(Indefinite)
Bus Idle