3 data length register (dlr) – Freescale Semiconductor MPC5200B User Manual
Page 664
Programmer’s Model of Message Storage
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor
19-25
19.6.3
Data Length Register (DLR)
This register keeps the data length field of the CAN frame.
DLC3 - DLC0 — Data Length Code bits
The data length code contains the number of bytes (data byte count) of the respective message. During the transmission of a remote frame,
the data length code is transmitted as programmed while the number of transmitted data bytes is always 0. The data byte count ranges from 0
to 8 for a data frame.
shows the effect of setting the DLC bits.
19.6.4
MSCAN Transmit Buffer Priority Register (TBPR)—MBAR + 0x0979 / 0x09F9
Table 19-29. Data Length Codes
Data Length Code
Data Byte Count
DLC3
DLC2
DLC1
DLC0
0
0
0
0
0
0
0
0
1
1
0
0
1
0
2
0
0
1
1
3
0
1
0
0
4
0
1
0
1
5
0
1
1
0
6
0
1
1
1
7
1
0
0
0
8
Table 19-30. MSCAN Transmit Buffer Priority Register
msb 0
1
2
3
4
5
6
7 lsb
R
PRIO7
PRIO6
PRIO5
PRIO4
PRIO3
PRIO2
PRIO1
PRIO0
W
RESET:
0
0
0
0
0
0
0
0
Bit
Name
Description
0:7
PRIO[7:0]
Register defines local priority of associated message buffer. Local priority is used for
MSCAN internal prioritization process and is defined to be highest for the smallest binary
number. MSCAN implements the following internal prioritization mechanism:
• All transmission buffers with a cleared TXEx flag participate in prioritization
immediately before start of frame (SOF) is sent.
• Transmission buffer with lowest local priority field wins prioritization.
• If more than one buffer has the same lowest priority, message buffer with lower index
number wins.