Renesas M32R/ECU Series User Manual page 640

13
(3) When the receive conditions are met
When the receive conditions in (2) 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. In addition, 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.
Notes: • The ID field and DLC value are written to the message slot.
• An undefined value is written to the extended ID area when receiving standard format frames.
• The data field is not written to.
• The RA and TRFIN bits are cleared to "0" after writing the received remote frame data.
(4) When the receive conditions are not met
The received data is discarded, and the CAN module waits for the next receive frame. No data is written to
the message slot.
(5) Operation after receiving a remote frame
The operation performed after receiving a remote frame differs depending on how automatic response is set.
1) When automatic response is disabled
The slot which has had reception completed goes to an inactive state and remains inactive (neither
transmit nor receive) until it is newly set in software.
2) When automatic response is enabled
After receiving a remote frame, the slot automatically changes to a data frame transmit slot and performs
the transmit operation described below. In this case, the transmitted data conforms to the ID and DLC of
the received remote frame.
• Selecting a transmit frame
The CAN module checks slots which have transmit requests (including remote frame transmit slots)
every intermission to determine the frame to transmit. If two or more transmit slots exist, frames are
transmitted in order of slot numbers beginning with the smallest.
• Transmitting a data frame
After determining the transmit slot, the CAN module sets the corresponding CAN Message Slot Control
Register's TRSTAT (Transmit/Receive Status) bit to "1" and starts transmitting.
• 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.
• Completion of data frame transmission
When data frame transmission has finished, the CAN Message Slot Control Register's TRFIN (Transmit/
Receive Finished) bit and the CAN Slot Interrupt Request Status Register are set to "1". Also, a
timestamp count value at which transmission has finished is written to the CAN Message Slot
Timestamp (C0MSLnTSP, C1MSLnTSP), and the transmit operation is thereby completed.
If the CAN slot interrupt request has been enabled, an interrupt request is generated at completion of
transmit operation. The slot which has had transmission completed goes to an inactive state and
remains inactive (neither transmit nor receive) until it is newly set in software.
13.8 Receiving Remote Frames
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CAN MODULE
32180 Group User's Manual (Rev.1.0)