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MC9S12KG128 Datasheet, PDF (304/600 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Chapter 9 Freescaleâs Scalable Controller Area Network (MSCANV2)
DLC3
0
0
0
0
0
0
0
0
1
Table 9-34. Data Length Codes
Data Length Code
DLC2
0
0
0
0
1
1
1
1
0
DLC1
0
0
1
1
0
0
1
1
0
DLC0
0
1
0
1
0
1
0
1
0
Data Byte
Count
0
1
2
3
4
5
6
7
8
9.3.3.4 Transmit Buffer Priority Register (TBPR)
This register deï¬nes the local priority of the associated message buffer. The local priority is used for the
internal prioritization process of the MSCAN and is deï¬ned to be highest for the smallest binary number.
The MSCAN implements the following internal prioritization mechanisms:
⢠All transmission buffers with a cleared TXEx ï¬ag participate in the prioritization immediately
before the SOF (start of frame) is sent.
⢠The transmission buffer with the lowest local priority ï¬eld wins the prioritization.
In cases of more than one buffer having the same lowest priority, the message buffer with the lower index
number wins.
R
W
Reset:
7
PRIO7
0
6
PRIO6
5
PRIO5
4
PRIO4
3
PRIO3
2
PRIO2
0
0
0
0
0
Figure 9-33. Transmit Buffer Priority Register (TBPR)
1
PRIO1
0
0
PRIO0
0
Read: Anytime when TXEx ï¬ag is set (see Section 9.3.2.7, âMSCAN Transmitter Flag Register
(CANTFLG)â) and the corresponding transmit buffer is selected in CANTBSEL (see Section 9.3.2.11,
âMSCAN Transmit Buffer Selection Register (CANTBSEL)â).
Write: Anytime when TXEx ï¬ag is set (see Section 9.3.2.7, âMSCAN Transmitter Flag Register
(CANTFLG)â) and the corresponding transmit buffer is selected in CANTBSEL (see Section 9.3.2.11,
âMSCAN Transmit Buffer Selection Register (CANTBSEL)â).
9.3.3.5 Time Stamp Register (TSRHâTSRL)
If the TIME bit is enabled, the MSCAN will write a special 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
MC9S12KG128 Data Sheet, Rev. 1.15
304
Freescale Semiconductor
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