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Section 20 Controller Area Network
R01UH0134EJ0400 Rev. 4.00 Page 1061 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
(1) Time Triggered Transmission
This module offers a H/W support to perform communication in Time Trigger mode in line with
the emerging ISO-11898-4 Level 1 Specification.
This section reports the basic procedures to use this mode.
Setting Time Trigger Mode
In order to set up the time trigger mode the following settings need to be used.
CMAX in CMAX_TEW must be programmed to a value different from 3'b111.
Bit 15 in TTCR0 has to be set, to start TCNTR.
Bit 6 in TTCR0 has to be cleared to prevent TCNTR from being cleared after a match.
DART in Mailboxes used for time-triggered transmission cannot be used, since for Time
Triggered Mailboxes, TXPR is not cleared to support periodic transmission.
Roles of Registers
The user registers of this module can be used to handle the main functions requested by the
TTCAN standard.
TCNTR Local Time
RFMK Ref_Mark
CYCTR Cycle Time = TCNTR - RFMK
RFTROFF Ref_Trigger_Offset for Mailbox-30
Mailbox-31 Mailbox dedicated to the reception of time reference message
Mailbox-30 Mailbox dedicated to the transmission of time reference message when
working as a potential time master
Mailbox-29 to 24 Mailboxes supporting time-triggered transmission
Mailbox-23 to 16 Mailboxes supporting reception without timestamp (may also be
implemented as Mailboxes supporting Event Triggered transmission)
Mailbox-15 to 0 Mailboxes supporting reception with timestamp timestamp (may also be
implemented as Mailboxes supporting Event Triggered transmission)
Tx-Trigger Time Time_Mark to specify when a message should be transmitted