
Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12HY/HA-Family Reference Manual, Rev. 1.05
334
Freescale Semiconductor
9.3.2.17
MSCAN Identier Acceptance Registers (CANIDAR0-7)
On reception, each message is written into the background receive buffer. The CPU is only signalled to
read the message if it passes the criteria in the identier acceptance and identier mask registers
(accepted); otherwise, the message is overwritten by the next message (dropped).
The acceptance registers of the MSCAN are applied on the IDR0–IDR3 registers (see
Section 9.3.3.1,For extended identiers, all four acceptance and mask registers are applied. For standard identiers, only
the rst two (CANIDAR0/1, CANIDMR0/1) are applied.
Module Base + 0x0010 to Module Base + 0x0013
Access: User read/write(1)
1. Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
76543210
R
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
W
Reset
00000000
Figure 9-20. MSCAN Identier Acceptance Registers (First Bank) — CANIDAR0–CANIDAR3
Table 9-22. CANIDAR0–CANIDAR3 Register Field Descriptions
Field
Description
7-0
AC[7:0]
Acceptance Code Bits — AC[7:0] comprise a user-dened sequence of bits with which the corresponding bits
of the related identier register (IDRn) of the receive message buffer are compared. The result of this comparison
is then masked with the corresponding identier mask register.
Module Base + 0x0018 to Module Base + 0x001B
Access: User read/write(1)
1. Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
76543210
R
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
W
Reset
00000000
Figure 9-21. MSCAN Identier Acceptance Registers (Second Bank) — CANIDAR4–CANIDAR7