atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 167

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

16. Controller Area Network - CAN
16.1
16.2
16.2.1
7647A–AVR–02/08
Features
CAN Protocol
Principles
The Controller Area Network (CAN) protocol is a real-time, serial, broadcast protocol with a very
high level of security. The ATmega32/64/M1/C1 CAN controller is fully compatible with the CAN
Specification 2.0 Part A and Part B. It delivers the features required to implement the kernel of
the CAN bus protocol according to the ISO/OSI Reference Model:
• The Data Link Layer
• The Physical Layer
The CAN controller is able to handle all types of frames (Data, Remote, Error and Overload) and
achieves a bitrate of 1 Mbit/s.
The CAN protocol is an international standard defined in the ISO 11898 for high speed and ISO
11519-2 for low speed.
CAN is based on a broadcast communication mechanism. This broadcast communication is
achieved by using a message oriented transmission protocol. These messages are identified by
using a message identifier. Such a message identifier has to be unique within the whole network
and it defines not only the content but also the priority of the message.
The priority at which a message is transmitted compared to another less urgent message is
specified by the identifier of each message. The priorities are laid down during system design in
the form of corresponding binary values and cannot be changed dynamically. The identifier with
the lowest binary number has the highest priority.
Bus access conflicts are resolved by bit-wise arbitration on the identifiers involved by each node
observing the bus level bit for bit. This happens in accordance with the "wired and" mechanism,
• Full Can Controller
• Fully Compliant with CAN Standard rev 2.0 A and rev 2.0 B
• 6 MOb (Message Object) with their own:
• 1 Mbit/s Maximum Transfer Rate at 8 MHz
• TTC Timer
• Listening Mode (for Spying or Autobaud)
– 11 bits of Identifier Tag (rev 2.0 A), 29 bits of Identifier Tag (rev 2.0 B)
– 11 bits of Identifier Mask (rev 2.0 A), 29 bits of Identifier Mask (rev 2.0 B)
– 8 Bytes Data Buffer (Static Allocation)
– Tx, Rx, Frame Buffer or Automatic Reply Configuration
– Time Stamping
- the Logical Link Control (LLC) sublayer
- the Medium Access Control (MAC) sublayer
- the Physical Signalling (PLS) sublayer
- not supported - the Physical Medium Attach (PMA)
- not supported - the Medium Dependent Interface (MDI)
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