May 16, 20001

2004 Edition2 USB Hub Designs John Garney Hub Working Group Chair, Intel Corporation Schumann Rafizadeh VP Engineering, Yi Shi Tong John Garney Hub Working Group Chair, Intel Corporation Schumann Rafizadeh VP Engineering, Yi Shi Tong

May 16, Hub Additions w Requirements and Architecture – Additions to USB1.1 w Transaction Translator w Bulk/Control Transaction Handling w Isochronous/Interrupt Transaction Handling w Additions to Chapter 11

May 16, Requirements: w Provide high-speed expansion w Isolate full/low-speed from high-speed – Avoid lower speed impact on HS, i.e., LS impact on FS w All USB2.0 Hub Ports support HS/FS/LS w Optional: standardized port indicators (LEDs)

May 16, System SW Client Driver USB 1.1 Device HS Hub USB 1.1 Hub USB 1.1 Device HS Device USB 2.0 Host Controller Controller Full/Low Speed High Speed Only (2 x 12Mb/s Capacity) Hub In High Speed System w Hub provides high-speed expansion (ala 1.1 hub) w Hub provides additional classic bus(es) – Same total number of devices per USB2.0 Host Controller (e.g. 127) w Greater end user value than classic hub – Performance, expansion and ease of use w Hub is user selected device (not required for all systems)

May 16, Reuse Classic Hub Design Knowledge Reuse Classic Hub Design Knowledge HS/Classic Hub State MachineHS/Classic Machine HS/Classic Hub Repeater Repeater Controller Controller High Speed Only Port Hub Classic Pieces w Repeater – High speed signaling u Also, FS/LS signaling for 1.1 compatibility – Reclocking w State Machine – HS termination sequencing u HS Detect, Reset, Suspend, Resume w Hub Controller – Respond to hub device class requests/events

May 16, Hub Architecture w Same as classic hub: – High & full/low-speed repeaters, determined by upstream facing link – Hub controller – No different then classic USB besides high-speed signaling w Minor changes from classic hub: – Hub state machine (HS detect, HS termination transitions, test mode) w New in hub: – Transaction Translator – Routing logic HS/Classic Hub Controller ControllerTransactionTranslatorTransactionTranslator Full/LowSpeed High Speed Only..... HS/Classic Hub State Machine Machine Routing Logic Port HS/Classic Hub Repeater Repeater

May 16, Routing Logic Routing Logic TransactionTranslatorTransactionTranslator Full/LowSpeed High Speed Only Port Repeater, Controller,... Port Hub New Pieces w Port Routing Logic – Controllable electrical connection between: u Full/Low (Transaction Translator), or u High-Speed (Repeater) – Route done once per device reset w Transaction Translator – Major addition for USB 2.0 – Uses split transaction protocol HC support.....

May 16, Host Controller / TT Interactions HostHost DeviceDevice TTTT X X2 TT buffers full/low speed transaction information (X) locally 1 – SPLIT-s, OUT, DATAx (Start-split) Host Controller issues start-split transaction to TT Host Controller issues start-split transaction to TT TTTT R R ,ACK TT buffers full/low speed transaction results (R) locally 3 - OUT, DATAx,... TT issues full/low speed transaction on downstream bus TT issues full/low speed transaction on downstream bus 6 - …,ACK 6 - …,ACK TT responds with results TT responds with results InterruptOutExample 5 – SPLIT-c, OUT, … (Complete-split) Host Controller issues complete-split transaction to TT Host Controller issues complete-split transaction to TT

May 16, Transaction Translator Overview w Two separate portions to Transaction Translator – Bulk/Control support – Interrupt/Isochronous support w Bulk/Control uses USB flow control to make progress – PING not used w Interrupt/Isochronous uses a scheduled full/low speed transaction pipeline w Separate buffers are used for each TT portion Transaction Translator Bulk & Control Bulk & Control Interrupt & Isochronous Interrupt & Isochronous

May 16, TT Bulk / Control w TT buffers 2 or more bulk/control transactions w TT issues full/low speed transaction when no periodic transactions pending w Host controller issues split transactions to TT – Allows starting/completing full/low-speed transactions each microframe – Normal approach of bandwidth reclamation is used – Tries to issue HS start-split; if successful, next attempt does complete-split TTTT Bulk/Ctrl #1 Bulk/Ctrl #2 High Speed Start-/Complete-Split Full/Low Speed Transaction

May 16, TT Int. / Isoch. Pipeline w Host software budgets when full/low-speed transaction will run w Host schedules start-split before earliest start time w Host schedules complete-split at latest finish times w Scheduling accounts for variation due to bit-stuffing and timeouts, etc. TTTT High Speed Start-Split High Speed Complete-Split Start-splitFIFOStart-splitFIFOComplete-splitFIFOComplete-splitFIFO StartHandlerStartHandlerCompleteHandlerCompleteHandler Full/LowHandlerFull/LowHandler

May 16, TTTT Start-split Start-splitFIFO FIFOComplete-splitFIFOComplete-splitFIFO Full/LowHandlerFull/LowHandler StartHandlerStartHandlerCompleteHandlerCompleteHandler X X2 TT buffers full/low speed transaction information locally 1 – SPLIT-s, OUT, DATAx Host Controller issues start-split transaction to TT 3 - OUT, DATAx,... TT issues full/low speed transaction on downstream bus 5 – SPLIT-c, OUT,... 5 – SPLIT-c, OUT,... Host Controller issues complete-split transaction to TT 6 - …,ACK 6 - …,ACK TT responds with results Example: Int. OUT Split Trans. R R ,ACK TT buffers full/low speed transaction results locally Start-split Start-splitFIFO FIFO

May 16, Hub Cost / Complexity Estimate w Classic Hub + new things – Classic Hub - implementation dependent, but knowable baseline – New things u Signaling Ô Required for any High-Speed device u Logic (routing, TT) u RAM (buffer space, transaction pipeline) w Total (approximate) – 40KGates Bytes with 4 downstream ports – 28KGates + (3KG * # of downstream ports) Bytes TT FIFOs TT Logic Port High-Speed Classic Hub Port Routing Logic

May 16, USB2.0 Hub Additions Summary w Hub Ports Support all Speeds (High/Full/Low) – Isolation of High and Full/Low Speeds via TT u Simultaneous High and Full/Low-Speed Transactions – Full/Low Speed (12Mb/s) bus per TT u Can be TT per hub or TT per port w TT Internals Overview – Bulk/Control buffering – Interrupt/Isochronous scheduled pipeline

January 10, Mega Hub Designs w Architecture – Cascaded Hub Design – Interleaved Hub Design

January 10, Mega Hub Designs w Cascaded Mega Hub w Host and Devices use the same TT & Buffers

January 10, Mega Hub Designs w Interleaved Mega Hub w Host and Devices use different TT & Buffers

January 10, Mega Hub Designs w Advantages of Cascaded Hubs – Ease of design and manufacture – Low Cost w Advantages of Interleaved Hubs – High Performance – Higher Capacity

January 10, Flash Storage Strategy w

January 10, Flash Storage Strategy w Current off-the-shelf Flash Storage disadvantages; – Lower reliability – Lower capacity – Lower bandwidth – Have lower performance w Advantages; – higher portability – higher availability – lower power consumption – wider applications (mobile phones, cameras, tablets, hand-held gadgets etc.) – Lower cost w The Flash Storage Strategy provides a roadmap of innovations that expand the advantages of Flash Storage devices and eliminate their restrictions and disadvantages. w This roadmap includes, Wear-out detection (Patent xxx), Flash Array (Patent xxx), Flash Hub (Patent xxx) and Flash Cluster.

January 10, Flash Storage Strategy - Testing w Device Testing – Flash Array/Flash RAID – HUB – Cluster w Range USB 2.0 & USB 3.0 Testing – Performance Goals u USB 2.0 up to 50 MB/Sec u USB 3.0 up to 500 MB/Sec – Capacity u Dependant on Class and number of mocules

January 10, Flash Storage Strategy - Testing w Speed Capacity USB 2.0 USB MB/SEC