MC68HC908GZ60 Datasheet, PDF (153/352 Pages) Freescale Semiconductor, Inc – Microcontrollers

Programmer’s Model of Message Storage
Addr.
Register
Bit 7
6
5
4
3
2
1
Bit 0
$05b0
Read:
IDR0
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
Write:
$05b1
Read:
IDR1
ID2
ID1
ID0
RTR
IDE (=0)
Write:
$05b2
Read:
IDR2
Write:
$05b3
Read:
IDR3
Write:
= Unimplemented
Figure 12-13. Standard Identifier Mapping
12.12.2 Identifier Registers
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 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 case of a transmit buffer, the flag indicates to the MSCAN08 what type of
identifier to send.
1 = Extended format, 29 bits
0 = Standard format, 11 bits
RTR — Remote Transmission Request
This flag reflects the status of the remote transmission request bit in the CAN frame. In case of a
receive buffer, it indicates the status of the received frame and supports the transmission of an
answering frame in software. In case of a transmit buffer, this flag defines the setting of the RTR bit to
be sent.
1 = Remote frame
0 = Data frame
MC68HC908GZ60 • MC68HC908GZ48 • MC68HC908GZ32 Data Sheet, Rev. 6
Freescale Semiconductor
153