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USB 2.0 Test Modes and Their Application

May 16, 2000. 2. USB 2.0 Test Modes and Their Application. Jon Lueker Intel Corporation. May 16, 2000. 3. Link Integrity Strategy. Define necessary and sufficient set of specifications for cables, upstream-facing ports, and downstream-facing portsDefine reproducible tests which allow testing of each element in isolationDefine required test modes which allow tests to be performed with standardized equipment and techniques.

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USB 2.0 Test Modes and Their Application

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    2. May 16, 2000 2 USB 2.0 Test Modes and Their Application Jon Lueker Intel Corporation

    3. May 16, 2000 3 Link Integrity Strategy Define necessary and sufficient set of specifications for cables, upstream-facing ports, and downstream-facing ports Define reproducible tests which allow testing of each element in isolation Define required test modes which allow tests to be performed with standardized equipment and techniques

    4. May 16, 2000 4 Specifications for a High-Speed Transmitter Source impedance Clock frequency DC Levels into reference load Transmit eye pattern into reference load At pins of transceiver (guideline) At USB receptacle (if no captive cable) At end of cable (if cable is captive) Minimum allowable rise/fall time

    5. May 16, 2000 5 Specifications for a High-Speed Receiver DC termination voltage and resistance Squelch threshold level Disconnect threshold level TDR (AC loading) limits Worst case eye patterns which must be recoverable At pins of transceiver (guideline) At USB receptacle (if no captive cable) At end of cable (if cable is captive)

    6. May 16, 2000 6 Specifications for USB Cable Maximum length and delay per meter (delay spec added in USB 1.1 ECN) Differential and common mode impedance (common mode spec added in ECN) Skew (tightened to 100 ps from 400 ps in ECN) Maximum allowable loss (added 200MHz and 400MHz points in ECN)

    7. May 16, 2000 7 Test Modes High-speed capable devices/hubs must support test modes Test modes enable repeatable testing SetFeature(TEST_MODE) and SetPortFeature(PORT_TEST) requests provide standard means of entering mode Exit action is also standardized Upstream facing port – power cycle Downstream facing port – hub reset

    8. May 16, 2000 8 Test Mode Test_SE0_NAK Port enters and remains in the high-speed idle state Regular actions, such as suspending, are inhibited Upstream-facing ports must respond to any IN token packet with a NAK handshake (if CRC is correct)

    9. May 16, 2000 9 Test Modes Test_J and Test_K Port enters and remains in the high-speed J or K state Regular actions, such as suspending, are inhibited

    10. May 16, 2000 10 Test Mode Test_Packet Port repetitively transmits defined test packet Packet is designed to contain the full range of pattern frequencies and duty factors

    11. May 16, 2000 11 Test Mode Test_Force_Enable Applies only to downstream–facing hub ports Required behaviors apply even if no device is attached Port must be enabled in high-speed mode Downstream packets must be repeated to the port

    12. May 16, 2000 12 Example: Testing a Self-Powered Device Testing Input Impedance and Termination Voltage Testing Output Levels Testing Transmit Waveforms Testing Receiver Sensitivity Testing Squelch Threshold

    13. May 16, 2000 13 Example: Testing Input Impedance and Termination Voltage Attach DUT to USB 2.0 host controller Reset the device and then issue request to place device in Test_SE0_NAK mode Unplug cable from device and replace it with test cable/fixture Measure DC output voltage on each line Measure DC resistance on each line Perform differential TDR test on outputs

    14. May 16, 2000 14 Example: Testing Output Levels Attach DUT to USB 2.0 host controller Reset the device and then issue request to place device in Test_J mode Unplug cable from device and replace it with test cable/fixture Measure output voltages into 45 Ohm loads to ground Repeat using Test_K

    15. May 16, 2000 15 Eye Pattern Test Fixture

    16. May 16, 2000 16 Example: Testing Transmit Waveforms Attach DUT to USB 2.0 host controller Reset the device and then issue request to place device in Test_Packet mode Unplug cable from device and replace it with high-frequency test cable/fixture Measure rise/fall time Capture single, complete occurrence of test packet on a transient capture instrument Perform eye pattern analysis on waveform record

    17. May 16, 2000 17 Example: Testing Receiver Sensitivity and Squelch Threshold Attach DUT to USB 2.0 host controller Reset the device and then issue request to place device in Test_SE0_NAK mode Unplug cable from device and replace it with test cable/fixture Using data generator, apply IN token packet while varying amplitude, frequency, and injected jitter Using a differential high-impedance probe, monitor the cable to see under which conditions device responds with NAK handshake

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