MC68HC908AT32 Datasheet, PDF (266/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

MSCAN Controller
Addr.
$05b0
$05b1
$05b2
$05b3
Register
IDR0
IDR1
IDR2
IDR3
Bit 7
6
5
4
3
2
Read:
ID10
ID9
ID8
ID7
ID6
ID5
Write:
Read:
ID2
ID1
ID0
RTR
IDE(0)
Write:
Read:
Write:
Read:
Write:
= Unimplemented
Figure 23-11. Standard Identifier Mapping
1
Bit 0
ID4
ID3
23.12.2 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 highest priority of an identifier is defined as the smallest binary number.
SRR — Substitute Remote Request Bit
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 Flag
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 Flag
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 allows the transmission of an answering
frame in software to be supported. In case of a transmit buffer, this flag defines the setting of the RTR
bit to be sent.
1 = Remote frame
0 = Data frame
MC68HC908AT32 Data Sheet, Rev. 3.1
266
Freescale Semiconductor