16.9.18.2 Time-Out Functions
To ensure that all messages are sent or received within a predefined period, each mailbox has its own time-out
register. If a message has not been sent or received by the time indicated in the time-out register and the
corresponding bit TOC[
n
] is set in the TOC register, a flag is set in the time-out status register (TOS).
For transmit mailboxes the TOS[
n
] flag is cleared when the TOC[
n
] bit is cleared or when the corresponding
TRS[
n
] bit is cleared, no matter whether due to successful transmission or abortion of the transmit request. For
receive mailboxes, the TOS[
n
] flag is cleared when the corresponding TOC[
n
] bit is cleared.
The CPU can also clear the time-out status register flags by writing a 1 into the time-out status register.
The message object time-out registers (MOTO) are implemented as a RAM. The state machine scans all the
MOTO registers and compares them to the TSC counter value. If the value in the TSC register is equal to or
greater than the value in the time-out register, and the corresponding TRS bit (applies to transmit mailboxes
only) is set, and the TOC[
n
] bit is set, the appropriate bit TOS[
n
] is set. Since all the time-out registers are
scanned sequentially, there can be a delay before the TOS[
n
] bit is set.
16.9.18.2.1 Message-Object Time-Out Registers (MOTO)
This register holds the time-out value of the TSC by which the corresponding mailbox data should be
successfully transmitted or received. Each mailbox has its own MOTO register.
Figure 16-33. Message-Object Time-Out Registers (MOTO)
31
0
MOTO31:0
R/W-x
LEGEND: R/W = Read/Write; -
n
= value after reset; x = indeterminate
Table 16-29. Message-Object Time-Out Registers (MOTO) Field Descriptions
Bit
Field
Value
Description
31:0
MOTO31:0
Message object time-out register. Limit-value of the time-stamp counter (TSC) to actually transmit
or receive the message.
16.9.18.2.2 Message-Object Time Stamp Registers (MOTS)
This register holds the value of the TSC when the corresponding mailbox data was successfully transmitted or
received. Each mailbox has its own MOTS register.
Figure 16-34. Message-Object Time Stamp Registers (MOTS)
31
0
MOTS31:0
R/W-x
LEGEND: R/W = Read/Write; -
n
= value after reset; x = indeterminate
Table 16-30. Message-Object Time Stamp Registers (MOTS) Field Descriptions
Bit
Field
Value
Description
31:0
MOTS31:0
Value of the time stamp counter (TSC) when the message has been actually received or
transmitted.
Controller Area Network (CAN)
1048
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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