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Lantronix DSTni-EX manual Block Diagram, I2C Background, Theory of Operation

Models: DSTni-EX

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Block Diagram

Block Diagram

Figure 3-1shows a block diagram of the DSTni I2C controller.

Figure 3-1. DSTni I2C Controller Block Diagram

Theory of Operation

I2C Background

The I2C bus is a popular serial, two-wire interface used in many systems because of its low overhead. Capable of 100 KHz operation, each device connected to the bus is software addressable by a unique address, with a simple master/slave protocol.

The I2C bus consists of two wires, serial data (SDA), and a serial clock (SCL), which carry information between the devices connected to the bus. This two-wire interface minimizes interconnections, so integrated circuits have fewer pins, and the number of traces required on printed circuit boards is reduced.

The number of devices connected to the same bus is limited only by a maximum bus capacitance of 400 pF. Both the SDA and SCL lines are bidirectional, connected to a positive supply voltage via a pull-up resistor. When the bus is free, both lines are HIGH. The output stages of devices connected to the bus must have an open-drain or open-collector to perform the wired-AND function.

Each device on the bus has a unique address and can operate as either a transmitter or receiver. In addition, devices can also be configured as masters or slaves.

A master is the device that initiates a data transfer on the bus and generates the clock signals to permit that transfer.

Any other device that is being addressed is considered a slave.

The I2C protocol defines an arbitration procedure to ensure that if more than one master simultaneously tries to control the bus, only one is allowed to do so and the message is not

corrupted. The arbitration and clock synchronization procedures defined in the I2C specification are supported by the DSTni I2C controller.

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Lantronix DSTni-EX manual I2C Background, Theory of Operation, 1. DSTni I2C Controller Block Diagram

Contents

DSTni-EX User Guide Section FivePage Copyright & Trademark LantronixTechnical Support Master DistributorWarranty Contents 1 About This User Guide2 SPI Controller 3 I2C ControllerList of Tables 5 CAN ControllersTable 3-17. Clock Control Register List of Figures 1 About This User Guide Intended Audience ConventionsNavigating Online Notes Notes are information requiring attentionOrganization 2 SPI Controller Theory of OperationSPI Background DSTni SPI ControllerSPI Controller Register Summary Table 2-1. SPI Controller Register SummarySPI Controller Register Definitions SPIDATA RegisterRESET Table 2-2. SPIDATA RegisterCTL Register RESETInterrupt Request Enable Phase SelectSPISTAT Register RESETTable 2-6. SPISTAT Register Table 2-7. SPISTAT Register DefinitionsSPISSEL Register Table 2-10. BCNT Bit SettingsRESET SelectO SignalDVDCNTRLO Register DVDCNTRHIRESET RESETFeatures 3 I2C ControllerBlock Diagram I2C BackgroundFigure 3-1. DSTni I2C Controller Block Diagram Theory of OperationMaster Transmit Mode I2C ControllerOperating Modes Table 3-1. Master Transmit Status Codes CodeI2C State Microprocessor ResponseServicing the Interrupt Table 3-2. Codes After Servicing Interrupts Master TransmitTransmitting Each Data Byte Table 3-3. Status Codes After Each Data Byte TransmitsAll Bytes Transmit Completely Master Receive ModeTable 3-4. Master Receive Status Codes CodeI 2C State Microprocessor ResponseServicing the Interrupt Table 3-5. Codes After Servicing Interrupt Master ReceiveSlave Transmit Mode Receiving Each Data ByteTable 3-6. Codes After Receiving Each Data Byte Slave Receive Mode Bus Clock Considerations Bus Clock SpeedClock Synchronization Bus ArbitrationProgrammer’s Reference I2C Controller Register SummaryResetting the I2C Controller Table 3-7. I 2C Controller Register SummaryI2C Controller Register Definitions Slave Address RegisterRESET General Call Address EnableData Register Table 3-10. Data RegisterControl Register Table 3-12. Control RegisterTable 3-13. Control Register Definitions Extended Slave AddressStatus Register Table 3-14. Status RegisterTable 3-15. Status Register Definitions BitsField Name DescriptionTable 3-18. Clock Control Register Definitions Clock Control RegisterTable 3-17. Clock Control Register Software Reset Register Extended Slave Address RegisterTable 3-21. Software Reset Register Table 3-22. Software Reset Register Definitions4 USB Controller FeaturesUSB Background USB InterruptUSB Core Theory of OperationUSB Hardware/Software Interface Digital Phase Lock Loop LogicMicroprocessor Interface Buffer Descriptor TableFigure 4-1. Buffer Descriptor Table Rx vs. Tx as a Target Device or HostTable 4-1. USB Data Direction Addressing BDT EntriesTable 4-2. 16-Bit USB Address Table 4-3. 16-Bit USB Address DefinitionsTable 4-4. BDT Data Used by USB Controller and Microprocessor USB Controller Determines…Microprocessor Determines… Table 4-5. USB Buffer Descriptor FormatTable 4-6. USB Buffer Descriptor Format Definitions BD OwnerDATA0/1 Transmit or Receive USB OwnershipUSB Transaction Figure 4-2. USB Token TransactionDedicated to host mode USB Register SummaryTable 4-7. USB Register Summary USB Register Definitions Interrupt Status RegisterTable 4-8. Interrupt Status Register Table 4-9. 16- Interrupt Status Register DefinitionsEnable/Disable USBRST Interrupt Sleep TimerError Condition USB ResetTable 4-11. 16- Error Interrupt Status Register Definitions Error RegisterTable 4-10. Error Interrupt Status Register Error interrupt with two functions Data Field Received Not 8 BitsCRC16 Failure PID check field failedLive USB Differential Receiver JSTATE Signal Live USB Single Ended Zero SignalStatus Register Table 4-12. Status RegisterUSB Reset Signal Host Mode Enable valid for host mode onlyResume Signaling BDT PDD ResetTable 4-15. 16- Address Register Definitions Address RegisterTable 4-14. Address Register Frame Number Registers RESETTable 4-16. Frame Number Register Table 4-17. Frame Number Register DefinitionsToken Register RESET Endpoint for Token CommandTable 4-18. Token Register Table 4-19. Token Register DefinitionsEndpoint Control Registers Endpoint EnableTable 4-21. Endpoint Control Registers Table 4-22. Endpoint Control Register DefinitionsHost Mode Operation Table 4-23. Endpoint Control Register DefinitionsSample Host Mode Operations Figure 3. Enable Host Mode and Configure a Target DeviceFigure 4. Full-Speed Bulk Data Transfers to a Target Device USB Pull-up/Pull-down Resistors Figure 4-5. Pull-up/Pull-down USBUSB Interface Signals USB Output EnableHOST Mode Enable Clock CLK5 CAN Controllers Data Exchanges and Communication Arbitration and Error CheckingCANBUS Background Table 5-1. Bit Rates for Different Cable Lengths CANBUS Speed and LengthFeatures CAN Register Summaries Register SummaryHex Offset RegisterHex Offset RegisterDetailed CAN Register Map Table 5-4. Detailed CAN Register MapAcceptance Filter Enable Register Hex OffsetRegister CAN Register Definitions TX Message RegistersFigure 5-1. TX Message Routing Sending a MessageTx Message Registers Table 5-5. TxMessage0ID28Table 5-6. TxMessage0ID12 Table 5-7. TxMessage0DataTable 5-12. TxMessage0Ctrl Flags Table 5-13. TxMessage0 Register DefinitionsMessage Identifier for Both Standard and Extended Messages Message DataRX Message Registers Figure 5-2. RX Message RoutingRx Message Registers Table 5-14. RxMessageID28Table 5-15. Rx Message ID28 Register Definitions Table 5-16. RxMessageID12Table 5-20. Rx Message Data Table 5-21. Rx Message Data 39 Register DefinitionsTable 5-22. Rx Message Data Table 5-23. Rx Message Data 23 Register DefinitionsTable 5-26. RxMessage RTR Table 5-27. Rx Message RTR Register DefinitionsTable 5-28. Rx Message Msg Flags Table 5-29. Rx Message Msg Flags Register DefinitionsError Count and Status Registers Table 5-30. Tx/Rx Error CountTable 5-31. Tx\Rx Error Count Register Definitions Table 5-32. Error StatusTable 5-34. Tx/Rx Message Level Register Table 5-35. Tx/Rx Message Level Register DefinitionsReserved rxlevel10Interrupt Flags Note The reset value of this register’s bits is indeterminateCRC Error Format ErrorInterrupt Enable Registers Table 5-38. Interrupt Enable RegistersTable 5-39. Interrupt Enable Register Definitions Bus Off State − int2n group error interruptsCAN Operating Mode Table 5-40. Interrupt Enable RegistersTable 5-41. Interrupt Enable Register Definitions Overload Condition − int3n group diagnostic interruptsCAN Configuration Registers Configuration Bit RateFigure 5-3. CAN Operating Mode Table 5-42. Bit Rate Divisor RegisterTable 5-44. Configuration Register Table 5-45. Configuration Register DefinitionsOverwrite Last Message CfgsjwBit Time tseg1 +tseg2 + time quanta TQAcceptance Filter and Acceptance Code Mask Table 5-46. Acceptance Filter Enable RegisterTable 5-47. Acceptance Filter Enable Register Definitions Table 5-48. Acceptance Mask 0 RegisterTable 5-50. Acceptance Mask Register ID Table 5-51. Acceptance Mask Register ID12 DefinitionsTable 5-52. Acceptance Mask Register Data Message DataTable 5-54. Acceptance Code Register Table 5-55. Acceptance Code Register DefinitionsTable 5-56. Acceptance Mask Register ID12 Table 5-57. Acceptance Mask Register ID12 DefinitionsCANbus Analysis Arbitration Lost Capture RegisterTable 5-60. Arbitration Lost Capture Register Table 5-61. Arbitration Lost Capture Register DefinitionsError Capture Register Table 5-62. Error Capture RegisterTable 5-63. Error Capture Register Definitions ErrorcodeNote The reset value of this register’s bits is indeterminate Table 5-65. Error Capture Register DefinitionsFrame Reference Register Table 5-64. Frame Reference RegisterCAN Bus Interface Interface ConnectionsFigure 5-6. CAN Connector Figure 5-5. CAN Bus InterfaceFigure 5-7. Power for CAN +5CANGNDCAN +24VFigure 5-8. CAN Transceiver and Isolation Circuits 0.01uf