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13.6.2 Data Frame Receive Operation
The following describes how data frame receive operation is performed. All these operations are
automatically performed in hardware.
(1) Acceptance filtering
When data reception is completed, the CAN module searches for slots sequentially from slot 0
(up to slot 15) that meet the receive conditions and are therefore eligible for the received
message.
The following shows the receive conditions for the slots that have been set to receive a data
frame.
[Conditions]
•
The received frame is a data frame.
•
The received ID and the slot ID are the same, with the ID mask register bits set to 0 being
ignored as "Don't care."
•
The standard and extended frame types are the same.
Note: When in BasicCAN mode, slots 14 and 15, even when set to receive a data frame, can
receive a remote frame too.
(2) When the receive conditions are met
When the receive conditions described in (1) 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 and at the same time writes the received data to the message slot. If the TRFIN
(transmit/receive finished) bit is already 1 at this time, the ML (message lost) bit also is set to 1,
indicating that the message slot has been overwritten. The message slot has all of its ID and DLC
fields overwritten, with an indeterminate value written to its unused area (e.g., the extended ID
field when set for standard frame or an unused data field).
In addition, the time stamp count value at the time of message reception is written along with the
received data to the CAN Message Slot Time stamp Register (CMSLnTSP). When the CAN
module finishes writing to the message slot, it sets the CAN slot interrupt status bit to 1. If the slot
has been enabled for interrupt, it generates an interrupt and waits for the next reception.
(3) When the receive conditions are not met
The CAN module discards the received frame and goes to the next transmit or receive operation.
It does not write to the message slot.
CAN MODULES
13.6 Receiving Data Frames
Summary of Contents for 32172
Page 20: ... This is a blank page 16 ...
Page 21: ...1 1 Overview 1 2 Block Diagram 1 3 Pin Functions 1 4 Pin Layout CHAPTER 1 CHAPTER 1 OVERVIEW ...
Page 44: ...1 1 24 Rev 1 0 This is a blank page Overview 1 4 Pin Layout ...
Page 58: ...2 2 14 Rev 1 0 This is a blank page CPU 2 6 Data Formats ...
Page 122: ...4 4 26 Rev 1 0 This is a blank page EIT 4 13 Precautions on EIT ...
Page 200: ...7 7 6 Rev 1 0 This is a blank page RESET 7 4 Precautions to Be Taken Immediately after Reset ...
Page 298: ...9 9 58 Rev 1 0 This is a blank page DMAC 9 4 Precautions on Using DMAC ...
Page 776: ...19 19 10 Rev 1 0 RAM BACKUP MODE 19 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Page 782: ...20 20 6 Rev 1 0 OSCILLATION CIRCUIT 20 2 Clock Generator Circuit This is a blank page ...
Page 856: ...23 23 26 Rev 1 0 This is a blank page ELECTRICAL CHARACTERISTICS 23 6 AC Characteristics ...
Page 857: ...24 1 A D Conversion Characteristics CHAPTER 24 CHAPTER 24 STANDARD CHARACTERISTICS ...
Page 859: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Page 865: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...