mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 337

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

Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
15.4
The following section details the organization of the receive and transmit message buffers and the
associated control registers.
To simplify the programmer interface, the receive and transmit message buffers have the same outline.
Each message buffer allocates 16 bytes in the memory map containing a 13 byte data structure.
An additional transmit buffer priority register (TBPR) is defined for the transmit buffers. Within the last
two bytes of this memory map, the MSCAN stores a special 16-bit time stamp, which is sampled from an
internal timer after successful transmission or reception of a message. This feature is only available for
transmit and receiver buffers if the TIME bit is set (see
(CANCTL0)”).
The time stamp register is written by the MSCAN. The CPU can only read these registers.
Freescale Semiconductor
AM[7:0]
Field
7:0
Reset
W
Figure 15-21. MSCAN Identifier Mask Registers (Second Bank) — CANIDMR4–CANIDMR7
R
Programmer’s Model of Message Storage
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
0
7
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Table 15-23. CANIDMR4–CANIDMR7 Register Field Descriptions
AM6
0
6
AM5
5
0
AM4
0
4
Description
Section 15.3.1, “MSCAN Control Register 0
AM3
0
3
Freescale’s Controller Area Network (MSCANV1)
AM2
0
2
AM1
0
1
AM0
0
0
15-21