Freescale Semiconductor, Inc.
MSCAN Controller
Programmer’s Model of Message Storage
Figure 17-12. Standard Identifier Mapping
(1)
REGISTER
R/W BIT 7
6
5
4
3
2
1
BIT 0
ADDR
R
$01x0
$01x1
$01x2
$01x3
IDR0
ID10
W
ID9
ID8
ID7
ID6
ID5
ID4
ID3
R
IDR1
IDR2
IDR3
ID2
W
ID1
ID0
RTR
IDE(0)
R
W
R
W
1. x is 4, 5, 6, or 7 depending on which buffer RxFG, Tx0, Tx1, or Tx2 respectively.
17.12.2 Identifier Registers (IDRn)
The identifiers consist of either 11 bits (ID10–ID0) for the standard, or 29
bits (ID28–ID0) for the extended format. ID10/28 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 highest for the smallest binary
number.
SRR — Substitute Remote Request
This fixed recessive bit is used only in extended format. It must be set
to 1 by the user for transmission buffers and will be stored as received
on the CAN bus for receive buffers.
IDE — ID Extended
This flag indicates whether the extended or standard identifier format
is applied in this buffer. In the case of a receive buffer the flag is set
as being received and indicates to the CPU how to process the buffer
identifier registers. In the case of a transmit buffer the flag indicates to
the msCAN12 what type of identifier to send.
0 = Standard format (11-bit)
1 = Extended format (29-bit)
68HC(9)12D60 — Rev 4.0
MOTOROLA
Advance Information
MSCAN Controller
301
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