Texas Instruments TMS320DM643X DMP Transmit Flow Control, Speed, Duplex, and Pause Frame Support

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Peripheral Architecture

2.9.2.6Transmit Flow Control

Incoming pause frames are acted upon, when enabled, to prevent the EMAC from transmitting any further frames. Incoming pause frames are only acted upon when the FULLDUPLEX and TXFLOWEN bits in the MAC control register (MACCONTROL) are set. Pause frames are not acted upon in half-duplex mode.

Pause frame action is taken if enabled, but normally the frame is filtered and not transferred to memory. MAC control frames are transferred to memory, if the RXCMFEN bit in the receive multicast/broadcast/promiscuous channel enable register (RXMBPENABLE) is set. The TXFLOWEN and FULLDUPLEX bits affect whether or not MAC control frames are acted upon, but they have no affect upon whether or not MAC control frames are transferred to memory or filtered.

Pause frames are a subset of MAC control frames with an opcode field of 0001h. Incoming pause frames are only acted upon by the EMAC if:

∙TXFLOWEN bit is set in M ACCONTROL

∙The frame’s length is 64 to RXMAXLEN bytes inclusive

∙The frame contains no CRC error or align/code errors

The pause time value from valid frames is extracted from the two bytes following the opcode. The pause time is loaded into the EMAC transmit pause timer and the transmit pause time period begins. If a valid pause frame is received during the transmit pause time period of a previous transmit pause frame then:

∙If the destination address is not equal to the reserved multicast address or any enabled or disabled unicast address, then the transmit pause timer immediately expires, or

∙If the new pause time value is 0, then the transmit pause timer immediately expires, else

∙The EMAC transmit pause timer immediately is set to the new pause frame pause time value. (Any remaining pause time from the previous pause frame is discarded).

If the TXFLOWEN bit in MACCONTROL is cleared, then the pause timer immediately expires.

The EMAC does not start the transmission of a new data frame any sooner than 512 bit-times after a pause frame with a nonzero pause time has finished being received (MRXDV going inactive). No transmission begins until the pause timer has expired (the EMAC may transmit pause frames in order to initiate outgoing flow control). Any frame already in transmission when a pause frame is received is completed and unaffected.

Incoming pause frames consist of:

∙A 48-bit destination address equal to one of the following:

–The reserved multicast destination address 01.80.C2.00.00.01h

–Any EMAC 48-bit unicast address. Pause frames are accepted, regardless of whether the channel is enabled or not.

∙The 16-bit length/type field containing the value 88.08h.

∙The 48-bit source address of the transmitting device.

∙The 16-bit pause opcode equal to 00.01h.

∙The 16-bit pause time. A pause-quantum is 512 bit-times.

∙Padding to 64-byte data length.

∙The 32-bit frame-check sequence (CRC word).

All quantities are hexadecimal and are transmitted most-significant byte first. The least-significant bit (LSB) is transferred first in each byte.

The padding is required to make up the frame to a minimum of 64 bytes. The standard allows pause frames longer than 64 bytes to be discarded or interpreted as valid pause frames. The EMAC recognizes any pause frame between 64 bytes and RXMAXLEN bytes in length.

2.9.2.7Speed, Duplex, and Pause Frame Support

The MAC operates at 10 Mbps or 100 Mbps, in half-duplex or full-duplex mode, and with or without pause frame support as configured by the host.

38 Ethernet Media Access Controller (EMAC)/SPRU941A –April 2007

Management Data Input/Output (MDIO)

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Contents Users Guide Submit Documentation Feedback Contents MAC Hash Address Register 1 MACHASH1 Appendix a Appendix BList of Figures Transmit Pacing Algorithm Test Register Tpacetest List of Tables Fifo Control Register Fifocontrol Field Descriptions Read This First Features Purpose of the PeripheralFunctional Block Diagram Emac and Mdio Block DiagramClock Control Signal DescriptionsIndustry Standards Compliance Statement Memory MapEmac and Mdio Signals Signal Type DescriptionEthernet Frame Description Ethernet Protocol OverviewEthernet Frame Format Field Bytes DescriptionPacket Buffer Descriptors Ethernet’s Multiple Access ProtocolProgramming Interface Basic Descriptor Description Typical Descriptor Linked ListTransmit and Receive Descriptor Queues Transmit and Receive Emac Interrupts Transmit Buffer Descriptor Format Example 1. Transmit Buffer Descriptor in C Structure FormatBuffer Offset Next Descriptor PointerBuffer Pointer Buffer LengthEnd of Queue EOQ Flag End of Packet EOP FlagOwnership Owner Flag Teardown Complete Tdowncmplt FlagReceive Buffer Descriptor Format Receive Buffer Descriptor FormatExample 2. Receive Buffer Descriptor in C Structure Format #define EmacdscflagjabberBuffer Length CRC Error Crcerror Flag Code Error Codeerror FlagAlignment Error Alignerror Flag Jabber FlagInternal Memory Emac Control ModuleNo Match Nomatch Flag Bus ArbiterMdio Module Components Mdio ModuleInterrupt Control Global PHY Detection and Link State Monitoring PHY Register User AccessMdio Clock Generator Active PHY MonitoringMdio Module Operational Overview Reading Data From a PHY Register Initializing the Mdio ModuleWriting Data To a PHY Register Example of Mdio Register Access Code Example 3. Mdio Register Access MacrosReceive DMA Engine Emac ModuleEmac Module Components Receive FifoTransmit Fifo Clock and Reset LogicTransmit DMA Engine MAC TransmitterReceive Control Media Independent Interface MIIData Reception Receive Inter-Frame IntervalCollision-Based Receive Buffer Flow Control Ieee 802.3x-Based Receive Buffer Flow ControlAdaptive Performance Optimization APO Transmit ControlCRC Insertion Interpacket-Gap IPG EnforcementTransmit Flow Control Speed, Duplex, and Pause Frame SupportReceive Channel Enabling Receive DMA Host ConfigurationPacket Receive Operation Receive Address MatchingReceive Channel Teardown Hardware Receive QOS SupportHost Free Buffer Tracking Promiscuous Receive Mode Receive Frame ClassificationReceive Frame Treatment Summary Receive Frame TreatmentMiddle of Frame Overrun Treatment Receive OverrunMiddle of Frame Overrun Treatment Receive and Transmit Latency Transmit DMA Host ConfigurationPacket Transmit Operation Transmit Channel TeardownTransfer Node Priority Reset ConsiderationsSoftware Reset Considerations Enabling the EMAC/MDIO Peripheral Hardware Reset ConsiderationsInitialization Emac Control Module InitializationExample 5. Mdio Module Initialization Code Example 4. Emac Control Module Initialization CodeMdio Module Initialization Emac Module Initialization Transmit Packet Completion Interrupts Interrupt SupportEmac Module Interrupt Events and Requests Receive Packet Completion InterruptsHost Error Interrupt Statistics InterruptLink Change Interrupt User Access Completion InterruptMdio Module Interrupt Events and Requests Proper Interrupt ProcessingEmulation Control Power ManagementEmulation Considerations Acronym Register Description Emac Control Module Interrupt Control Register EwctlEmac Control Module Registers Bit FieldEmac Control Module Interrupt Timer Count Register Ewinttcnt Mdio Version Register Version Field Descriptions Mdio Version Register VersionManagement Data Input/Output Mdio Registers Mdio Control Register Control Mdio Control Register Control Field DescriptionsPHY Acknowledge Status Register Alive Field Descriptions PHY Acknowledge Status Register AlivePHY Link Status Register Link PHY Link Status Register Link Field DescriptionsNo Mdio link change event Will clear the event and writing a 0 has no effect No Mdio user command complete event USERINTMASKED0 and USERINTMASKED1 correspond to USERACCESS0 WS-0 Userintmaskclear Mdio User Access Register 0 USERACCESS0 Mdio User Access Register 0 USERACCESS0 Field DescriptionsPhyadrmon Mdio User PHY Select Register 0 USERPHYSEL0Linksel Linkintenb Bit Field Value DescriptionMdio User Access Register 1 USERACCESS1 Mdio User Access Register 1 USERACCESS1 Field DescriptionsMdio User PHY Select Register 1 USERPHYSEL1 Mdio User PHY Select Register 1 USERPHYSEL1Ethernet Media Access Controller Emac Registers Ethernet Media Access Controller Emac Registers Offset Acronym Register DescriptionOffset Acronym Register Description Network Statistics RegistersTransmit Control Register Txcontrol Field Descriptions Transmit Identification and Version Register TxidverTransmit Control Register Txcontrol Txtdnch Transmit Teardown Register TxteardownTransmit Teardown Register Txteardown Field Descriptions Receive Control Register Rxcontrol Field Descriptions Receive Identification and Version Register RxidverReceive Control Register Rxcontrol Rxtdnch Receive Teardown Register RxteardownReceive Teardown Register Rxteardown Field Descriptions Transmit Interrupt Status Unmasked Register Txintstatraw TX7PENDTransmit Interrupt Status Masked Register Txintstatmasked Transmit Interrupt Status Masked Register TxintstatmaskedTransmit Interrupt Mask Set Register Txintmaskset TX7MASKTransmit Interrupt Mask Clear Register Txintmaskclear Transmit Interrupt Mask Clear Register TxintmaskclearUserint Linkint MAC Input Vector Register MacinvectorMAC Input Vector Register Macinvector Field Descriptions Hostpend Statpend Rxpend TxpendReceive Interrupt Status Unmasked Register Rxintstatraw RX7PENDReceive Interrupt Status Masked Register Rxintstatmasked Receive Interrupt Status Masked Register RxintstatmaskedReceive Interrupt Mask Set Register Rxintmaskset RX7MASKReceive Interrupt Mask Clear Register Rxintmaskclear Receive Interrupt Mask Clear Register RxintmaskclearHostpend Statpend MAC Interrupt Status Unmasked Register MacintstatrawMAC Interrupt Status Masked Register Macintstatmasked Hostmask Statmask MAC Interrupt Mask Set Register MacintmasksetMAC Interrupt Mask Clear Register Macintmaskclear HostmaskRxcsfen Rxcefen Rxcafen Rxpasscrc Rxqosen RxnochainRxcmfen RxpromchFrames containing errors are filtered Receive multicast channel select Receive Unicast Enable Set Register Rxunicastset RXCH7ENReceive Unicast Clear Register Rxunicastclear Receive Unicast Clear Register RxunicastclearReceive Maximum Length Register Rxmaxlen Field Descriptions Receive Maximum Length Register RxmaxlenReceive Buffer Offset Register Rxbufferoffset Rxfilterthresh Reserved RX nFLOWTHRESH FFhReceive Channel 0-7 Free Buffer Count Register RXnFREEBUFFER MAC Control Register Maccontrol MAC Control Register Maccontrol Field DescriptionsSent. Full-duplex mode no outgoing pause frames are sent LoopbackMAC Status Register Macstatus MAC Status Register Macstatus Field DescriptionsMAC Status Register Macstatus Field Descriptions Bit Field Value DescriptionEmulation Control Register Emcontrol Field Descriptions Emulation Control Register EmcontrolFifo Control Register Fifocontrol Fifo Control Register Fifocontrol Field DescriptionsMAC Configuration Register Macconfig Field Descriptions MAC Configuration Register MacconfigSoft Reset Register Softreset Soft Reset Register Softreset Field DescriptionsMAC Source Address Low Bytes Register Macsrcaddrlo MAC Source Address High Bytes Register MacsrcaddrhiMAC Hash Address Register 1 MACHASH1 Field Descriptions MAC Hash Address Register 1 MACHASH1MAC Hash Address Register 2 MACHASH2 MAC Hash Address Register 2 MACHASH2 Field DescriptionsBack Off Test Register Bofftest Field Descriptions Back Off Test Register BofftestTransmit Pacing Algorithm Test Register Tpacetest Receive Pause Timer Register Rxpause Field Descriptions Receive Pause Timer Register RxpauseTransmit Pause Timer Register Txpause Transmit Pause Timer Register Txpause Field DescriptionsMAC Address Low Bytes Register Macaddrlo Field Descriptions MAC Address Low Bytes Register MacaddrloMAC Address High Bytes Register Macaddrhi Macindex MAC Index Register MacindexMAC Index Register Macindex Field Descriptions TX nHDP Transmit Channel 0-7 Completion Pointer Register TXnCP Receive Channel 0-7 Completion Pointer Register RXnCPBroadcast Receive Frames Register Rxbcastframes Network Statistics RegistersGood Receive Frames Register Rxgoodframes Multicast Receive Frames Register RxmcastframesPause Receive Frames Register Rxpauseframes Receive CRC Errors Register RxcrcerrorsReceive Alignment/Code Errors Register Rxaligncodeerrors Receive Oversized Frames Register RxoversizedReceive Frame Fragments Register Rxfragments Receive Jabber Frames Register RxjabberReceive Undersized Frames Register Rxundersized Filtered Receive Frames Register RxfilteredGood Transmit Frames Register Txgoodframes Receive QOS Filtered Frames Register RxqosfilteredReceive Octet Frames Register Rxoctets Pause Transmit Frames Register Txpauseframes Broadcast Transmit Frames Register TxbcastframesMulticast Transmit Frames Register Txmcastframes Deferred Transmit Frames Register TxdeferredTransmit Multiple Collision Frames Register Txmulticoll Transmit Underrun Error Register TxunderrunTransmit Single Collision Frames Register Txsinglecoll Transmit Late Collision Frames Register TxlatecollTransmit and Receive 64 Octet Frames Register FRAME64 Transmit Carrier Sense Errors Register TxcarriersenseTransmit Octet Frames Register Txoctets Network Octet Frames Register Netoctets Receive DMA Overruns Register Rxdmaoverruns Appendix a Glossary Table A-1. Physical Layer Definitions Term DefinitionTable B-1. Document Revision History Reference Additions/Modifications/DeletionsProducts Applications DSP
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