Remote Frame Receive Operation - Mitsubishi Electric M32R Series User Manual

Mitsubishi 32-bit risc single-chip microcomputers

Table of Contents

13.8.2 Remote Frame Receive Operation

The following describes remote frame receive operation. The operations described below are

automatically performed in hardware.

(1) Setting the RA (Remote Active) bit

When H'60 (Transmit Request, Remote) or H'70 (Transmit Request, Remote, Automatic

Response Disable) is written to the CAN Message Slot Control Register, the RA (Remote Active)

bit is set to 1, indicating that the corresponding slot is to handle remote frames.

(2) Acceptance filtering

When the CAN module finished receiving data, it starts searching for the slot that satisfies

conditions for receiving the received message sequentially from slot 0 (up to slot 15). The

following shows receive conditions for slots that have been set for data frame reception.

[Conditions]

• The receive frame is a remote frame.

• The receive ID and the slot ID are identical, assuming the ID Mask Register bits set to 0 are

"Don't care bit."

• The standard and extended frame types are the same.

(3) When receive conditions are met

When receive conditions in (2) above are met, the CAN module sets the CAN Message Slot

Control Register's TRSTAT (Transmit/Receive Status) and TRFIN (Transmit/Receive Finished)

bits to 1 while at the same time writing the received data to the message slot. Furthermore, a time

stamp count value at the time the message was received is written to the CAN Message Slot

Time Stamp (C0MSLnTSP) along with the received data. When the CAN module finished writing

to the message slot, it sets the CAN Slot Interrupt Status bit to 1. If the interrupt for the slot has

been enabled, an interrupt request is generated.

Note 1:The ID field and DLC value are written to the message slot.

Note 2:When receiving standard format frames, an indeterminate value is written to the

extended ID area.

Note 3:The data field is not accessed for write.

Note 4:The RA and TRFIN bits are cleared to 0 after writing the remote frame received data.

(4) When receive conditions are not met

The received frame is discarded, and the CAN module waits for the next receive frame. No data

is written to the message slot.

13.8 Receiving Remote Frames