mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 258

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

16.11.2 Identifier Registers
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.
while
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.
258
msCAN12 Controller
Figure 16-12
details the identifier structure used in the extended format. ID10/ID28 is the most
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
Tx1, or Tx2, respectively.
(1)
Figure 16-11
M68HC12B Family Data Sheet, Rev. 9.1
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
details the identifier structure used in the standard format
DATA LENGTH REGISTER
IDENTIFIER REGISTER 0
IDENTIFIER REGISTER 1
IDENTIFIER REGISTER 2
IDENTIFIER REGISTER 3
Register Name
UNUSED
UNUSED
(2)
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