MC68HC08GZ32 Datasheet, PDF (145/320 Pages) Freescale Semiconductor, Inc – Microcontrollers

Programmer’s Model of Control Registers
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
CMCR0 is set
12.13.13 MSCAN08 Identifier Mask Registers (CIDMR0–CIDMR3)
The identifier mask registers specify which of the corresponding bits in the identifier acceptance register
are relevant for acceptance filtering. For standard identifiers it is required to program the last three bits
(AM2–AM0) in the mask register CIDMR1 to ‘don’t care’.
CIDMRO Address: $0514
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
Write:
Reset:
Unaffected by reset
CIDMR1 Address: $0515
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
Write:
Reset:
Unaffected by reset
CIDMR2 Address: $0516
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
Write:
Reset:
Unaffected by reset
CIDMR3 Address: $0517
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
Write:
Reset:
Unaffected by reset
Figure 12-28. Identifier Mask Registers (CIDMR0–CIDMR3)
AM7–AM0 — Acceptance Mask Bits
If a particular bit in this register is cleared, this indicates that the corresponding bit in the identifier
acceptance register must be the same as its identifier bit before a match will be detected. The message
will be accepted if all such bits match. If a bit is set, it indicates that the state of the corresponding bit
in the identifier acceptance register will not affect whether or not the message is accepted.
1 = Ignore corresponding acceptance code register bit.
0 = Match corresponding acceptance code register and identifier bits.
NOTE
The CIDMR0–CIDMR3 registers can be written only if the SFTRES bit in
the CMCR0 is set
MC68HC08GZ32 Data Sheet, Rev. 3
Freescale Semiconductor
145