XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 280

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

msCAN12 Controller
16.11.2 Identifier Registers
Data Sheet
280
NOTE:
All bits of the 13-byte data structure are undefined out of reset.
The receive buffer can be read anytime but cannot be written. The transmit buffers
can be read or written anytime.
The Bosch CAN 2.0A and 2.0B protocol specifications allow for two different sizes
of message identifiers. The Bosch CAN 2.0A specification requires an 11-bit
identifier in the message buffer and the Bosch CAN 2.0B specification requires a
29-bit identifier in the message buffer. The resulting message buffers are referred
to as standard and extended formats, respectively.
The identifier registers (IDRn) in the memory map can be configured to create
either the 11-bit (IDR10–IDR0) identifier necessary for the standard format or the
29-bit (IDR28–IDR0) identifier necessary for the extended format.
details the identifier structure used in the standard format while
details the identifier structure used in the extended format. ID10/ID28 is the most
significant bit and is transmitted first on the bus during the arbitration procedure.
The priority of an identifier is defined to be the highest for the smallest binary
number.
Address
1. x is 4, 5, 6, or 7 depending on which buffer, RxFG, Tx0,
2. Not applicable for receive buffers.
Figure 16-10. Message Buffer Organization
01xC
01xD
01x0
01x1
01x2
01x3
01x4
01x5
01x6
01x7
01x8
01x9
01xA
01xB
01xE
01xF
1)
Tx1, or Tx2, respectively.
msCAN12 Controller
(
TRANSMIT BUFFER PRIORITY REGISTER
DATA SEGMENT REGISTER 0
DATA SEGMENT REGISTER 1
DATA SEGMENT REGISTER 2
DATA SEGMENT REGISTER 3
DATA SEGMENT REGISTER 4
DATA SEGMENT REGISTER 5
DATA SEGMENT REGISTER 6
DATA SEGMENT REGISTER 7
DATA LENGTH REGISTER
IDENTIFIER REGISTER 0
IDENTIFIER REGISTER 1
IDENTIFIER REGISTER 2
IDENTIFIER REGISTER 3
Register Name
UNUSED
UNUSED
M68HC12B Family — Rev. 8.0
(2)
Figure 16-12
Figure 16-11
MOTOROLA