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Chapter 34 CAN Controller
4.CAN Application
4.5 Acceptance Filtering of Received Messages
When the arbitration and control field (Iden IDE + RTR + DLC) of an incoming message is completely
shifted into the Rx/Tx Shift Register of the CAN Core, the Message Handler FSM starts the scanning of the
Message RAM for a matching valid Message Object.
To scan the Message RAM for a matching Message Object, the Acceptance Filtering unit is loaded with the
arbitration bits from the CAN Core shift register. Then the arbitration and mask fields (including MsgVal,
UMask, NewDat, and EoB) of Message Object 1 are loaded into the Acceptance Filtering unit and compared
with the arbitration field from the shift register. This is repeated with each following Message Object until a
matching Message Object is found or until the end of the Message RAM is reached.
If a match occurs, the scanning is stopped and the Message Handler FSM proceeds depending on the type of
frame (Data Frame or Remote Frame) received.
4.6 Reception of Data Frame
The Message Handler FSM stores the message from the CAN Core shift register into the respective Message
Object in the Message RAM. Not only the data bytes, but all arbitration bits and the Data Length Code are
stored into the corresponding Message Object. This is implemented to keep the data bytes connected with the
identifier even if arbitration mask registers are used.
The NewDat bit is set to indicate that new data (not yet seen by the CPU) has been received. The CPU should
reset NewDat when it reads the Message Object. If at the time of the reception the NewDat bit was already
set, MsgLst is set to indicate that the previous data (supposedly not seen by the CPU) is lost. If the RxIE bit is
set, the IntPnd bit is set, causing the Interrupt Register to point to this Message Object.
The TxRqst bit of this Message Object is reset to prevent the transmission of a Remote Frame, while the
requested Data Frame has just been received.
4.7 Reception of Remote Frame
When a Remote Frame is received, three different configurations of the matching Message Object have to be
considered:
1) Dir = ‘1’ (direction = transmit), RmtEn = ‘1’, UMask = ‘1’ or ’0’
At the reception of a matching Remote Frame, the TxRqst bit of this Message Object is set. The rest of the
Message Object remains unchanged.
2) Dir = ‘1’ (direction = transmit), RmtEn = ‘0’, UMask = ’0’
At the reception of a matching Remote Frame, the TxRqst bit of this Message Object remains unchanged; the
Remote Frame is ignored.
3) Dir = ‘1’ (direction = transmit), RmtEn = ‘0’, UMask = ’1’
At the reception of a matching Remote Frame, the TxRqst bit of this Message Object is reset. The arbitration
and control field (Iden IDE + RTR + DLC) from the shift register is stored into the Message Object in the
Message RAM and the NewDat bit of this Message Object is set. The data field of the Message Object
remains unchanged; the Remote Frame is treated similar to a received Data Frame.
4.8 Receive / Transmit Priority
The receive/transmit priority for the Message Objects is attached to the message number. Message Object 1
has the highest priority, while Message Object 32 (the highest implemented message object number) has the
lowest priority. If more than one transmission request is pending, they are serviced due to the priority of the
corresponding Message Object.
4.9 Configuration of a Transmit Object
Figure 4-2
shows how a Transmit Object should be initialised.
Summary of Contents for FR Family FR60 Lite
Page 2: ...FUJITSU LIMITED ...
Page 3: ...FR60 32 BIT MICROCONTROLLER MB91460 Series User s Manual ...
Page 15: ...xi ...
Page 16: ...xii ...
Page 38: ...22 Chapter 2 MB91460 Rev A Rev B Overview 4 Block Diagram ...
Page 128: ...112 Chapter 4 CPU Architecture 9 Addressing ...
Page 153: ...137 Chapter 8 Device State Transition 3 State Transition Diagram ...
Page 154: ...138 Chapter 8 Device State Transition 3 State Transition Diagram ...
Page 169: ...153 Chapter 9 Reset 10 Caution ...
Page 170: ...154 Chapter 9 Reset 10 Caution ...
Page 180: ...164 Chapter 10 Standby 7 Q A ...
Page 182: ...166 Chapter 10 Standby 8 Caution ...
Page 199: ...183 Chapter 12 Instruction Cache 2 Main body structure Figure 2 3 I Cache Address Map ...
Page 200: ...184 Chapter 12 Instruction Cache 2 Main body structure Figure 2 4 I Cacheable Area ...
Page 222: ...206 Chapter 13 Clock Control 8 Caution ...
Page 232: ...216 Chapter 14 PLL Interface 7 Caution ...
Page 236: ...220 Chapter 15 CAN Clock Prescaler 3 Registers ...
Page 288: ...272 Chapter 19 Timebase Timer 8 Caution ...
Page 314: ...298 Chapter 22 Main Oscillation Stabilisation Timer 8 Caution ...
Page 326: ...310 Chapter 23 Sub Oscillation Stabilisation Timer 8 Caution ...
Page 348: ...332 Chapter 25 External Interrupt 8 Caution ...
Page 398: ...382 Chapter 26 DMA Controller 6 DMA External Interface ...
Page 402: ...386 Chapter 27 Delayed Interrupt 8 Caution ...
Page 412: ...396 Chapter 28 Bit Search 8 Caution ...
Page 521: ...505 Chapter 30 I O Ports 3 Port Register Settings ...
Page 522: ...506 Chapter 30 I O Ports 3 Port Register Settings ...
Page 574: ...558 Chapter 31 External Bus 4 Endian and Bus Access Byte Access ...
Page 628: ...612 Chapter 31 External Bus 13 Notes on Using the External Bus Interface ...
Page 706: ...690 Chapter 33 I2C Controller 4 Programming Flow Charts ...
Page 748: ...732 Chapter 34 CAN Controller 4 CAN Application ...
Page 762: ...746 Chapter 35 Free Run Timer 8 Caution ...
Page 790: ...774 Chapter 37 Output Compare 8 Caution ...
Page 838: ...822 Chapter 39 Programmable Pulse Generator 8 Caution ...
Page 850: ...834 Chapter 40 Pulse Frequency Modulator 4 PFM Operation and Setting ...
Page 886: ...870 Chapter 42 Sound Generator 3 Registers ...
Page 900: ...884 Chapter 43 Stepper Motor Controller 4 Caution ...
Page 939: ...923 Chapter 47 LCD Controller 3 Configuration Figure 3 2 Register List ...
Page 943: ...927 Chapter 47 LCD Controller 4 Registers Correspondence between VRAM and Common Segment Pins ...
Page 964: ...948 Chapter 48 Clock Monitor 8 Caution ...
Page 994: ...978 Chapter 51 Low Voltage Reset Interrupt 3 Registers ...
Page 998: ...982 Chapter 52 Regulator Control 3 Registers ...
Page 1008: ...992 Chapter 53 Fixed Mode Reset Vector BOOT ROM 5 Bootloader Update Strategy ...
Page 1024: ...1008 Chapter 54 Flash Memory 8 Caution ...
Page 1032: ...1016 Chapter 55 Flash Security 4 Register ...
Page 1034: ...1018 Chapter 56 Electrical Specification ...
Page 1035: ...FR60 MB91460 Series Hardware Manual European Microcontroller Design Centre Author MBo ...
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