Lantronix DSTni-EX manual CAN Register Definitions, TX Message Registers, 1. TX Message Routing

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CAN Register Definitions

CAN Register Definitions

TX Message Registers

To avoid priority inversion issues in the transmit path, three transmit buffers are available with a built-in priority arbiter. When a message is transmitted, the priority arbiter evaluates all pending messages and selects the one with the highest priority. The message priority is re-evaluated after each message abort event such as arbitration loss.

uP Bus

Figure 5-1. TX Message Routing

TxMessage 0

PRIORITY

TxMessage 0		ARBITER		CAN Module

TxMessage 0

CAN BUS

Sending a Message

The following sequence describes how to send a message.

1.Write message into one of the Transmit Message Holding registers TxMessage0/1/2).

2.Request transmission by setting the respective TRX flag. This flag remains set as long as the message holding registers contains this message. The content of the message buffer must not be changed while the TRX flag is set.

3.The TRX flags remain set as long as the message transmit request is pending.

4.The successful transfer of a message is indicated by the respective tx_xfer interrupt and by releasing the TRX flag. Depending on the tx_level configuration settings, an additional interrupt source tx_msg is available to indicate that the Message Holding registers are empty or below a certain level.

Removing a Message from a Transmit Holding Register

A message can be removed from one of the three Transmit Holding registers (TxMessage0/1/2) by setting the TxAbort flag. Use following procedure to remove the contents of a particular TxMessage buffer:

5.Set TxAbort to request the message removal.

6.This flag remains set as long as the message abort request is pending. It is cleared when either the message won arbitration (tx_xmit interrupt active) or the message was removed (tx_xmit interrupt inactive).

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Contents Section Five DSTni-EX User GuidePage Master Distributor Copyright & TrademarkLantronix Technical SupportWarranty 3 I2C Controller Contents1 About This User Guide 2 SPI Controller5 CAN Controllers List of TablesTable 3-17. Clock Control Register List of Figures 1 About This User Guide Notes Notes are information requiring attention Intended AudienceConventions Navigating OnlineOrganization DSTni SPI Controller 2 SPI ControllerTheory of Operation SPI BackgroundTable 2-1. SPI Controller Register Summary SPI Controller Register SummaryTable 2-2. SPIDATA Register SPI Controller Register DefinitionsSPIDATA Register RESETWire-O CTL RegisterInterrupt Request Enable Phase SelectInterrupt Request SPISTAT RegisterTable 2-6. SPISTAT Register Table 2-7. SPISTAT Register DefinitionsTable 2-8. SPISSEL Register SPISSEL RegisterTable 2-10. BCNT Bit Settings SelectO SignalTable 2-12. DVDCNTRLO Register Definitions DVDCNTRLO RegisterDVDCNTRHI Table 2-11. DVDCNTRLO Register3 I2C Controller FeaturesFigure 3-1. DSTni I2C Controller Block Diagram Block DiagramI2C Background Master Transmit Mode I2C ControllerOperating Modes Microprocessor Response Table 3-1. Master Transmit Status CodesCode I2C StateTable 3-2. Codes After Servicing Interrupts Master Transmit Servicing the InterruptMaster Receive Mode Transmitting Each Data ByteTable 3-3. Status Codes After Each Data Byte Transmits All Bytes Transmit CompletelyTable 3-4. Master Receive Status Codes Table 3-5. Codes After Servicing Interrupt Master Receive Slave Transmit Mode Receiving Each Data ByteTable 3-6. Codes After Receiving Each Data Byte Slave Receive Mode Bus Arbitration Bus Clock ConsiderationsBus Clock Speed Clock SynchronizationTable 3-7. I 2C Controller Register Summary Programmer’s ReferenceI2C Controller Register Summary Resetting the I2C ControllerTable 3-8. Slave Address Register I2C Controller Register DefinitionsSlave Address Register General Call Address EnableTable 3-10. Data Register Data RegisterExtended Slave Address Control RegisterTable 3-12. Control Register Table 3-13. Control Register DefinitionsTable 3-14. Status Register Status RegisterStatus Code Table 3-15. Status Register DefinitionsTable 3-16. Status Codes Table 3-18. Clock Control Register Definitions Clock Control RegisterTable 3-17. Clock Control Register Table 3-22. Software Reset Register Definitions Software Reset RegisterExtended Slave Address Register Table 3-21. Software Reset Register4 USB Controller Serial Interface Engine USB BackgroundUSB Interrupt USB CoreBuffer Descriptor Table USB Hardware/Software InterfaceDigital Phase Lock Loop Logic Microprocessor InterfaceRx vs. Tx as a Target Device or Host Figure 4-1. Buffer Descriptor TableTable 4-3. 16-Bit USB Address Definitions Table 4-1. USB Data DirectionAddressing BDT Entries Table 4-2. 16-Bit USB AddressTable 4-5. USB Buffer Descriptor Format Table 4-4. BDT Data Used by USB Controller and MicroprocessorUSB Controller Determines… Microprocessor Determines…USB Ownership Table 4-6. USB Buffer Descriptor Format DefinitionsBD Owner DATA0/1 Transmit or ReceiveFigure 4-2. USB Token Transaction USB TransactionDedicated to host mode USB Register SummaryTable 4-7. USB Register Summary Table 4-9. 16- Interrupt Status Register Definitions USB Register DefinitionsInterrupt Status Register Table 4-8. Interrupt Status RegisterUSB Reset Enable/Disable USBRST InterruptSleep Timer Error ConditionTable 4-11. 16- Error Interrupt Status Register Definitions Error RegisterTable 4-10. Error Interrupt Status Register PID check field failed Error interrupt with two functionsData Field Received Not 8 Bits CRC16 FailureTable 4-13. Status Register Definitions Live USB Differential Receiver JSTATE SignalLive USB Single Ended Zero Signal Table 4-12. Status RegisterBDT PDD Reset USB Reset SignalHost Mode Enable valid for host mode only Resume SignalingTable 4-15. 16- Address Register Definitions Address RegisterTable 4-14. Address Register Frame Number Frame Number RegistersTable 4-16. Frame Number Register Table 4-17. Frame Number Register DefinitionsToken Register Table 4-20. Valid PID Tokens Endpoint for Token CommandTable 4-18. Token Register Table 4-19. Token Register DefinitionsTable 4-22. Endpoint Control Register Definitions Endpoint Control RegistersEndpoint Enable Table 4-21. Endpoint Control RegistersTable 4-23. Endpoint Control Register Definitions Host Mode OperationFigure 3. Enable Host Mode and Configure a Target Device Sample Host Mode OperationsFigure 4. Full-Speed Bulk Data Transfers to a Target Device Figure 4-5. Pull-up/Pull-down USB USB Pull-up/Pull-down ResistorsClock CLK USB Interface SignalsUSB Output Enable HOST Mode Enable5 CAN Controllers Data Exchanges and Communication Arbitration and Error CheckingCANBUS Background Table 5-1. Bit Rates for Different Cable Lengths CANBUS Speed and LengthRegister CAN Register SummariesRegister Summary Hex OffsetRegister Table 5-4. Detailed CAN Register Map Detailed CAN Register MapHex Offset Acceptance Filter Enable RegisterRegister Sending a Message CAN Register DefinitionsTX Message Registers Figure 5-1. TX Message RoutingTable 5-7. TxMessage0Data Tx Message RegistersTable 5-5. TxMessage0ID28 Table 5-6. TxMessage0ID12Message Data Table 5-12. TxMessage0Ctrl FlagsTable 5-13. TxMessage0 Register Definitions Message Identifier for Both Standard and Extended MessagesFigure 5-2. RX Message Routing RX Message RegistersTable 5-16. RxMessageID12 Rx Message RegistersTable 5-14. RxMessageID28 Table 5-15. Rx Message ID28 Register DefinitionsTable 5-23. Rx Message Data 23 Register Definitions Table 5-20. Rx Message DataTable 5-21. Rx Message Data 39 Register Definitions Table 5-22. Rx Message DataTable 5-29. Rx Message Msg Flags Register Definitions Table 5-26. RxMessage RTRTable 5-27. Rx Message RTR Register Definitions Table 5-28. Rx Message Msg FlagsTable 5-32. Error Status Error Count and Status RegistersTable 5-30. Tx/Rx Error Count Table 5-31. Tx\Rx Error Count Register Definitionstxlevel10 Table 5-34. Tx/Rx Message Level RegisterTable 5-35. Tx/Rx Message Level Register Definitions rxlevel10Format Error Interrupt FlagsNote The reset value of this register’s bits is indeterminate CRC ErrorBus Off State − int2n group error interrupts Interrupt Enable RegistersTable 5-38. Interrupt Enable Registers Table 5-39. Interrupt Enable Register DefinitionsOverload Condition − int3n group diagnostic interrupts CAN Operating ModeTable 5-40. Interrupt Enable Registers Table 5-41. Interrupt Enable Register DefinitionsTable 5-42. Bit Rate Divisor Register CAN Configuration RegistersConfiguration Bit Rate Figure 5-3. CAN Operating ModeCfgsjw Table 5-44. Configuration RegisterTable 5-45. Configuration Register Definitions Overwrite Last Messagetime quanta TQ Bit Timetseg1 + tseg2 +Table 5-48. Acceptance Mask 0 Register Acceptance Filter and Acceptance Code MaskTable 5-46. Acceptance Filter Enable Register Table 5-47. Acceptance Filter Enable Register DefinitionsD5556 Table 5-50. Acceptance Mask Register IDTable 5-51. Acceptance Mask Register ID12 Definitions Table 5-52. Acceptance Mask Register DataTable 5-57. Acceptance Mask Register ID12 Definitions Table 5-54. Acceptance Code RegisterTable 5-55. Acceptance Code Register Definitions Table 5-56. Acceptance Mask Register ID12Table 5-61. Arbitration Lost Capture Register Definitions CANbus AnalysisArbitration Lost Capture Register Table 5-60. Arbitration Lost Capture RegisterErrorcode Error Capture RegisterTable 5-62. Error Capture Register Table 5-63. Error Capture Register DefinitionsStuff Bit Inserted Table 5-65. Error Capture Register DefinitionsFrame Reference Register Table 5-64. Frame Reference RegisterFigure 5-5. CAN Bus Interface CAN Bus InterfaceInterface Connections Figure 5-6. CAN Connector+24V Figure 5-7. Power for CAN+5CAN GNDCAN0.01uf Figure 5-8. CAN Transceiver and Isolation Circuits