mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 345

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

15.4.5
This register defines the local priority of the associated message transmit buffer. The local priority is used
for the internal prioritization process of the MSCAN and is defined to be highest for the smallest binary
number. The MSCAN implements the following internal prioritization mechanisms:
In cases of more than one buffer having the same lowest priority, the message buffer with the lower index
number wins.
Read: Anytime when TXEx flag is set (see
(CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see
“MSCAN Transmit Buffer Selection Register
Write: Anytime when TXEx flag is set (see
(CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see
“MSCAN Transmit Buffer Selection Register
15.4.6
If the TIME bit is enabled, the MSCAN will write a time stamp to the respective registers in the active
transmit or receive buffer as soon as a message has been acknowledged on the CAN bus (see
Freescale Semiconductor
•
•
Reset:
All transmission buffers with a cleared TXEx flag participate in the prioritization immediately
before the SOF (start of frame) is sent.
The transmission buffer with the lowest local priority field wins the prioritization.
W
R
Transmit Buffer Priority Register (TBPR)
Time Stamp Register (TSRH–TSRL)
PRIO7
0
7
DLC3
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
0
0
0
0
0
0
0
0
1
Figure 15-34. Transmit Buffer Priority Register (TBPR)
PRIO6
6
0
DLC2
0
0
0
0
1
1
1
1
0
Table 15-33. Data Length Codes
Data Length Code
PRIO5
0
5
Section 15.3.6, “MSCAN Transmitter Flag Register
Section 15.3.6, “MSCAN Transmitter Flag Register
(CANTBSEL)”).
(CANTBSEL)”).
PRIO4
DLC1
4
0
0
0
1
1
0
0
1
1
0
PRIO3
0
3
Freescale’s Controller Area Network (MSCANV1)
DLC0
0
1
0
1
0
1
0
1
0
PRIO2
2
0
Data Byte
Count
PRIO1
0
1
2
3
4
5
6
7
8
Section 15.3.10,
Section 15.3.10,
0
1
PRIO0
0
0
15-29