mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 336

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

Freescale’s Controller Area Network (MSCANV1)
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
15.3.16 MSCAN Identifier Mask Registers (CANIDMR0–CANIDMR7)
The identifier mask register specifies which of the corresponding bits in the identifier acceptance register
are relevant for acceptance filtering. To receive standard identifiers in 32 bit filter mode, it is required to
program the last three bits (AM[2:0]) in the mask registers CANIDMR1 and CANIDMR5 to “don’t care.”
To receive standard identifiers in 16 bit filter mode, it is required to program the last three bits (AM[2:0])
in the mask registers CANIDMR1, CANIDMR3, CANIDMR5, and CANIDMR7 to “don’t care.”
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
15-20
AM[7:0]
AC[7:0]
Field
Field
7:0
7:0
Figure 15-19. MSCAN Identifier Acceptance Registers (Second Bank) — CANIDAR4–CANIDAR7
Reset
Reset
W
R
Figure 15-20. MSCAN Identifier Mask Registers (First Bank) — CANIDMR0–CANIDMR3
W
R
Acceptance Code Bits — AC[7:0] 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.
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 is detected. The message
is 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 does not affect whether or not the message is accepted.
0 Match corresponding acceptance code register and identifier bits
1 Ignore corresponding acceptance code register bit (don’t care)
AM7
AC7
0
7
0
7
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Table 15-22. CANIDMR0–CANIDMR3 Register Field Descriptions
Table 15-21. CANIDAR4–CANIDAR7 Register Field Descriptions
AM6
AC6
6
0
0
6
AM5
AC5
0
5
0
5
AM4
AC4
0
4
0
4
Description
Description
AM3
AC3
3
0
0
3
AM2
AC2
0
2
0
2
Freescale Semiconductor
AM1
AC1
0
1
0
1
AM0
AC0
0
0
0
0