Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

MIPI DevCon 2016: Versatile Software Solution for MIPI C-PHY TX Testing


Published on

C-PHY has emerged as an interface alternative to D-PHY in MIPI camera applications. By decreasing toggle rate and increasing bandwidth, C-PHY offers systems designers more options for controlling EMI and power within a system, while maintaining high performance. However, testing C-PHY presents unique challenges, due to the need to monitor 3 lines simultaneously, as well as unique encoding and decoding methods. To address these challenges, UNH-IOL has created the C-PHY GUI tool. Similar to the widely used D-PHY GUI tool, C-PHY-GUI interfaces with oscilloscopes from various vendors. In this presentation, Paul Willis of UNH-IOL discusses the methodology behind C-PHY GUI, the challenges of building and testing it, and how to use it to easily test a C-PHY implementation.

Published in: Mobile
  • Want to preview some of our plans? You can get 50 Woodworking Plans and a 440-Page "The Art of Woodworking" Book... Absolutely FREE ➤➤
    Are you sure you want to  Yes  No
    Your message goes here
  • Be the first to like this

MIPI DevCon 2016: Versatile Software Solution for MIPI C-PHY TX Testing

  1. 1. Versatile Software Solution for MIPI C-PHY TX Testing Paul Willis UNH-IOL
  2. 2. Contents •  Who is the UNH-IOL? •  C-PHY TX Testing Tool Overview •  Physical Test Setup •  Clock and Data Recovery •  HS Packet Decode •  HS TX tests 2
  3. 3. UNH-IOL • MIPI Member since 2007 • Helped develop D-PHY Test Suite • Authored DPHYGUI Test Tool • Active test house for MIPI CSI, MIPI DSI, and MIPI D-PHY • Active in the Test Work Group • Work with several other Organizations to develop new technologies • Employ 100 university students 3
  4. 4. Testing MIPI C-PHY TX • Address issue of missing reference platform for performing C-PHY CTS TX tests • The industry has need for this software • Will be available for purchase to MIPI members • Meant to complement oscilloscope software package offerings 4
  5. 5. CPHYGUI Overview • MATLAB based software measurement tool • Evaluate PHY TX characteristics • Capture, import, and process waveforms •  Can download captures or import saved waveform files from Tektronix, Keysight, LeCroy, and Rhode & Schwarz oscilloscopes • Decode HS packets and LP sequences • Display and manage measurement results in GUI • Load/save measurement results • Command Line Interface 5
  6. 6. CPHYGUI 6
  7. 7. Test Setup 7 •  Real time oscilloscope •  High impedance probes •  C-PHY Reference Termination Board •  RTB may be used as probing point with probe tips soldered to the board DUT (P339) Probing Point C-PHY RTB Oscilloscope Computer CPHYGUI Da A/B/C Da A/B/C Ch 1/2/3 Da A/B/C GPIB / Ethernet
  8. 8. Clock and Data Recovery •  Lowpass filter data •  Find differential edge times •  Throw out edges from out of spec UI (too long/short) •  Find mode of UI length •  Run second pass using previously estimated UI length 8
  9. 9. Decoder •  Byte level decode of HS burst packets •  Protocol aware (CSI-2 and DSI) planned •  LP decoder planned •  Output to console •  Option to save log to text file 9
  10. 10. HS-TX Tests •  Capture from oscilloscope or import from file •  Sample rate above 5 GS/s and burst length of at least 5 thousand symbols suggested. •  Cropped single burst: 10
  11. 11. TLPX, T3-PREPARE, T3-PREAMBLE, and T3-SYNC •  HS entry timers measured as described in CTS •  TLPX: Time between VA and VC crossing VIL,MAX (550 mV). •  T3-PREPARE: Time between end of TLPX and HS-0 (+/- 40 mV). •  T3-PREAMBLE: Verifies length of preamble (in place of following tests). •  T3-PREBEGIN/T3-PROGSEQ/T3-PREEND: To be implemented. •  T3-SYNC: verify sync word (3,4,4,4,4,4,4,3) after preamble 11
  12. 12. VOD (max strong, min weak HS-0 and HS-1) •  Eye based measurements performed on all three differential pairs (VOD-AB, VOD-BC, VOD-CA) •  Measured at -20% of UI •  Calculate ΔVOD by subtracting absolute value of maximum strong 1 from absolute value of strong 0. •  Take highest value from all three differential pairs 12
  13. 13. VOHHS •  Mean of single ended waveform taken at -20% of UI •  Applicable to all 3 single ended lines 13
  14. 14. VCPTX and ΔVCPTX(HS) •  14
  15. 15. T3-POST •  Verify that the last 7 symbols in the burst are the “4” symbol 15