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Section 20 Controller Area Network
R01UH0134EJ0400 Rev. 4.00 Page 1069 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
In case of Merged Arbitrating Window the slot for transmission goes from the Tx_Trig of the
Mailbox opening the Window (TTW = 10 bin) to the end to the TEW of the Mailbox closing the
Window (TTW = 11 bin).The TXPR can be modified at any time. This module ensures the
transmission of Time Triggered messages is always scheduled correctly. However, in order to
guarantee the correct schedule, there are some important rules that are :
TTT (Tx Trigger Time) can be modified during configuration mode.
TTT cannot be set outside the range of Time_Ref, which specifies the length of basic cycle.
This could cause a scheduling problem.
TXPR is not automatically cleared for periodic transmission. If a periodic transmission
needs to be cancelled, the corresponding TXCR bit needs to be set by the application.
Example of Time Triggered System
The following diagram shows a simple example of how time trigger system works using this
module in time slave mode.
TTT24 TTT25 TTT26 TTT27 TTT28 TTT29
CCR = 0
Mailbox-24 (Tx)
Mailbox-28 (Tx)
Mailbox-28 (Tx)
Mailbox-29 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-25 to 27 (Tx)
Mailbox-24 (Tx)
Mailbox-24 (Tx)
Mailbox-24 (Tx)
time
reference
exclusive
window
exclusive
window
merged arbitrating window arbitrating
window
CCR = 1
CCR = 2
CCR = 3
CCR = 4
CCR = 5
CCR = 6
CCR = 7
Figure 20.22 Example of Time trigger system as Time Slave