october 10, 20001. 2 usb onthego ed beeman hewlett packard
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October 10, 2000 1
October 10, 2000 2
USBOnTheGo
USBOnTheGo
Ed BeemanEd BeemanHewlett PackardHewlett Packard
October 10, 2000 3
OnTheGo CharterOnTheGo Charter
Address the unique needs of portable devicesAddress the unique needs of portable devices– Connector sizeConnector size– Dual-role:Dual-role:
Sometimes peripheral (camera uploads pictures to PC)Sometimes peripheral (camera uploads pictures to PC) Sometimes host (camera sends pictures to printer)Sometimes host (camera sends pictures to printer)
Maintain spirit of USBMaintain spirit of USB Minimize deviations from core specMinimize deviations from core spec
October 10, 2000 4
Use Model ExamplesUse Model Examples
Exchange picturesExchange pictures
Upload pictures to webUpload pictures to web
Print picturesPrint pictures
CameraCamera
Cell PhoneCell Phone
PrinterPrinter
CameraCamera
Exchange songsExchange songsMP3 playerMP3 playerMP3 playerMP3 player
Exchange Contact infoExchange Contact info
Print call infoPrint call info
Upload pictures to webUpload pictures to web
Cell PhoneCell Phone
PrinterPrinter
CameraCamera
Cell PhoneCell Phone
Synchronize phone list, meetingsSynchronize phone list, meetings
Upload picturesUpload pictures
Download songsDownload songs
Cell PhoneCell Phone
CameraCamera
MP3 playerMP3 player
PCPCFunctionsFunctionsSlaveSlaveMasterMaster
October 10, 2000 5
Why USB?Why USB?
Ubiquitous…NowUbiquitous…Now CheapCheap ReliableReliable Good performanceGood performance Gates are cheap, easy to add light host controllerGates are cheap, easy to add light host controller Wireless may play stronger role in futureWireless may play stronger role in future
October 10, 2000 6
Smaller ConnectorsSmaller Connectors
Now: Now: – ECN to core specECN to core spec– A to mini-B cableA to mini-B cable– Mini-B receptacleMini-B receptacle
Future: Future: – Mini-A to mini-B and mini-Mini-A to mini-B and mini-
A to B cablesA to B cables– Mini-AB receptacleMini-AB receptacle– Not yet sanctioned – Not yet sanctioned –
waiting for OTG specwaiting for OTG spec
October 10, 2000 7
Mini-AB receptaclesMini-AB receptacles
Accepts Accepts eithereither mini-A mini-A oror mini-B plug mini-B plug– Mini-A plug => Master, Mini-B plug => SlaveMini-A plug => Master, Mini-B plug => Slave– 55thth pin is shorted to ground in mini-A plug (no 5 pin is shorted to ground in mini-A plug (no 5thth wire) wire)
Dual function allows small footprint, with no Dual function allows small footprint, with no implied hubimplied hub
Warning: don’t use mini-AB receptacle yetWarning: don’t use mini-AB receptacle yet– Wait for OTG master capabilityWait for OTG master capability– Breaks bus – cable inserted wrong and not reversibleBreaks bus – cable inserted wrong and not reversible
October 10, 2000 8
Dual Role DevicesDual Role Devices
100% compliant as a peripheral device100% compliant as a peripheral device Additional limited host capabilityAdditional limited host capability
– 4mA Vbus4mA Vbus– Supported device listSupported device list
Hub support is optional Hub support is optional – Primarily for single device to one other devicePrimarily for single device to one other device
Can be extended to full host capabilityCan be extended to full host capability
Not peer-to-peerNot peer-to-peer– Same USB protocolSame USB protocol
October 10, 2000 9
Master Negotiation ProtocolMaster Negotiation Protocol
Effectively turns cable aroundEffectively turns cable around– Two dual-role devicesTwo dual-role devices– Mini-A to mini-B cableMini-A to mini-B cable– Default slave (mini-B end) wants to start conversationDefault slave (mini-B end) wants to start conversation
OperationOperation– Master enables MNP in OTG slave with Set FeatureMaster enables MNP in OTG slave with Set Feature– Slave disconnectsSlave disconnects– Master asserts pull-upMaster asserts pull-up– Slave issues reset and SOFSlave issues reset and SOF– Slave enumerates and begins activitySlave enumerates and begins activity– On Suspend, Master drops pull-up and resumes Master roleOn Suspend, Master drops pull-up and resumes Master role
October 10, 2000 10
Lots of work leftLots of work left
OTG Specification ScheduleOTG Specification Schedule– V0.6 on Sept 26 – Spec not yet completeV0.6 on Sept 26 – Spec not yet complete– V0.7 in Oct/Nov – all issues addressed in spec, final V0.7 in Oct/Nov – all issues addressed in spec, final
format, still some unresolved issuesformat, still some unresolved issues– V0.8 by Year end – finish prototypesV0.8 by Year end – finish prototypes– V1.0 by 2Q01V1.0 by 2Q01
Compliance definition just startingCompliance definition just starting Logo variant?Logo variant?
October 10, 2000 11
Issues raised by OnTheGoIssues raised by OnTheGo
Benefit to consuming < 4mA on VbusBenefit to consuming < 4mA on Vbus Multiple cablesMultiple cables
– A:B, A:mini-B, mini-A:mini-B, mini-A:B?A:B, A:mini-B, mini-A:mini-B, mini-A:B? Masters that don’t support all devicesMasters that don’t support all devices
– Targeted device listTargeted device list Greater need for device class support Greater need for device class support
– E.g., Printer page descriptionE.g., Printer page description
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