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Chapter 14 Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XDP512 Data Sheet, Rev. 2.11
Freescale Semiconductor 647
Module Base + 0x00X1
76543210
R
ID20 ID19 ID18 SRR (=1) IDE (=1) ID17 ID16 ID15
W
Reset: xxxxxxxx
Figure 14-26. Identifier Register 1 (IDR1) — Extended Identifier Mapping
Table 14-27. IDR1 Register Field Descriptions — Extended
Field Description
7:5
ID[20:18]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
4
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 is stored as received on the CAN bus for receive buffers.
3
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 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 MSCAN what type of identifier to send.
0 Standard format (11 bit)
1 Extended format (29 bit)
2:0
ID[17:15]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
Module Base + 0x00X2
76543210
R
ID14 ID13 ID12 ID11 ID10 ID9 ID8 ID7
W
Reset: xxxxxxxx
Figure 14-27. Identifier Register 2 (IDR2) — Extended Identifier Mapping
Table 14-28. IDR2 Register Field Descriptions — Extended
Field Description
7:0
ID[14:7]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.