MC68HC908AT32 Datasheet, PDF (279/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Programmer’s Model of Control Registers
23.13.12 MSCAN08 Identifier Acceptance Registers
On reception each message is written into the background receive buffer. The CPU is only signalled to
read the message, however, if it passes the criteria in the identifier acceptance and identifier mask
registers (accepted). Otherwise, the message will be overwritten by the next message (dropped).
The acceptance registers of the MSCAN08 are applied on the IDR0 to IDR3 registers of incoming
messages in a bit by bit manner.
For extended identifiers, all four acceptance and mask registers are applied. For standard identifiers only
the first two (IDAR0 and IDAR1) are applied. In the latter case, the mask register, CIDMR1, the three last
bits (AC2–AC0) must be programmed to don’t care.
Register Name and Address: CIDAR0 — $0510
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Write:
Reset:
Unaffected by reset
Register Name and Address: CIDAR1 — $0511
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Write:
Reset:
Unaffected by reset
Register Name and Address: CIDAR2 — $0512
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Write:
Reset:
Unaffected by reset
Register Name and Address: CIDAR3 — $0513
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Write:
Reset:
Unaffected by reset
Figure 23-25. Identifier Acceptance Registers
(CIDAR0–CIDAR3)
AC7–AC0 — Acceptance Code Bits
AC7–AC0 comprise a user-defined sequence of bits with which the corresponding bits of the related
identifier register (IDRn) of the receive message buffer are compared. The result of this comparison is
then masked with the corresponding identifier mask register.
NOTE
The CIDAR0–CIDAR3 registers can be written only if the SFTRES bit in the
MSCAN08 module control register is set
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
279