16.9.19.3 Message-Control Register (MSGCTRL)
For a transmit mailbox, this register specifies the number of bytes to be transmitted and the transmission priority.
It also specifies the remote-frame operation.
Note
As part of the CAN module initialization process, all the bits of the MSGCTRL
n
registers must first be
initialized to zero before proceeding to initialize the various bit fields to the desired values.
The register MSGCTRL(
n
) can only be written if the mailbox
n
is configured for transmission
(CANMD[
n
] (CANMD.31-0)=0) or if the mailbox is disabled (CANME[
n
] (CANME.31-0) =0).
Figure 16-38. Message-Control Register (MSGCTRL)
31
16
Reserved
R-0
15
13
12
8
7
5
4
3
0
Reserved
TPL
Reserved
RTR
DLC
R-0
RW-x
R-0
RW-x
RW-x
LEGEND: RW = Read any time, write when mailbox is disabled or configured for transmission; -
n
= value after reset; x = indeterminate
Table 16-34. Message-Control Register (MSGCTRL) Field Descriptions
Bit
Field
Value
Description
31:13
Reserved
Reserved
12:8
TPL.4:0
Transmit-priority level. This 5-bit field defines the priority of this mailbox as compared to the other
31 mailboxes. The highest number has the highest priority. When two mailboxes have the same
priority, the one with the higher mailbox number is transmitted. TPL applies only for transmit
mailboxes. TPL is not used in SCC-mode.
7:5
Reserved
Reserved
4
RTR
Remote-transmission-request bit
1
For receive mailbox: If the TRS flag is set, a remote frame is transmitted and the corresponding
data frame is received in the same mailbox. Once the remote frame is sent, the TRS bit of the
mailbox is cleared by CAN.
For transmit mailbox: If the TRS flag is set, a remote frame is transmitted, but the corresponding
data frame has to be received in another mailbox.
0
No remote frame is requested.
3:0
DLC 3:0
Data-length code. The number in these bits determines how many data bytes are sent or received.
Valid value range is from 0 to 8. Values from 9 to 15 are not allowed.
Controller Area Network (CAN)
1052
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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