32186 datasheet(741/1032 Pages) RENESAS

741 / 1032 page

CAN MODULE

13-131

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

13.7 Transmitting Remote Frames

(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

written 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 31). 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 30 and 31 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

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.

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