Renesas M32R/ECU Series User Manual page 635

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(4) If lost in CAN bus arbitration or a CAN bus error occurs
If the CAN module lost in CAN bus arbitration or a CAN bus error occurs in the middle of transmission, the
CAN module clears the CAN Message Slot Control Register's TRSTAT (Transmit/Receive Status) bit to "0".
If the CAN module requested a transmit abort, the transmit abort is accepted and the message slot is enabled
for write.
(5) Completion of remote frame transmission
When remote frame transmission finishes, the timestamp count value at which transmission finished is writ-
ten to the CAN Message Slot Timestamp (C0MSLnTSP, C1MSLnTSP) and the CAN Message Slot Control
Register's RA (Remote Active) bit is cleared to "0". In addition, the CAN Slot Interrupt Request Status bit is
set to "1" by completion of transmission, but the CAN Message Slot Control Register's TRFIN (Transmit/
Receive Finished) bit is not set to "1". If the CAN slot interrupt request has been enabled, an interrupt request
is generated when transmission has finished.
(6) Receiving a data frame
When remote frame transmission finishes, the slot automatically starts functioning as a data frame receive slot.
(7) Acceptance filtering
When the CAN module finished receiving data, it starts searching for the slot that satisfies the conditions for
receiving the received message, sequentially from slot 0 (up to slot 15). The following shows receive condi-
tions for the slots that have been set for data frame reception.
[Conditions]
• The received frame is a data frame.
• The receive ID and the slot ID are identical, assuming the ID Mask Register bits set to "0" are "Don't care."
• The standard and extended frame types are the same.
Note: • In BasicCAN mode, slots 14 and 15 cannot be used as a transmit slot.
(8) When the receive conditions are met
When the receive conditions in (7) above are met, the CAN module sets the CAN Message Slot Control
Register's TRSTAT (Transmit/Receive Status) bit and TRFIN (Transmit/Receive Finished) bit to "1" while at
the same time writing the received data to the message slot. If the TRFIN (Transmit/Receive Finished) bit is
already set to "1" at this time, the CAN module also sets the ML (Message Lost) bit to "1", indicating that the
message slot has been overwritten. The message slot has both of its ID and DLC fields entirely overwritten
and has an undefined value written in its unused area (e.g., extended ID field during standard frame recep-
tion and an unused data field).
Furthermore, a timestamp count value at which the message was received is written to the CAN Message
Slot Timestamp (C0MSLnTSP, C1MSLnTSP) along with the received data. When the CAN module finished
writing to the message slot, it sets the CAN Slot Interrupt Request Status bit to "1". If the interrupt request for
the slot has been enabled, the CAN module generates an interrupt request and enters a wait state for the
next reception.
Note: • If the CAN module receives a corresponding data frame before sending a remote frame, it stores the
received data frame in the slot and does not transmit the remote frame.
(9) When the receive conditions are not met
The received frame is discarded, and the CAN module goes to the next transmit/receive operation without
writing to the message slot.
13.7 Transmitting Remote Frames
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CAN MODULE
32180 Group User's Manual (Rev.1.0)