MIPI DevCon Bangalore 2017: C-PHY and How it Enables Next Generation Display and Camera Implementations
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MIPI C-PhySM utilizes a three-phase encoding scheme to enhance transport efficiency, enabling next-generation imaging, vision, and display applications. The protocol features include unmapped words that facilitate robust control, transmission, and messaging. Applications within MIPI CSI-2SM and DSI-2SM can leverage these capabilities for improved communication and efficiency.
MIPI DevCon Bangalore 2017: C-PHY and How it Enables Next Generation Display and Camera Implementations
- 1. Mohamed Hafed Introspect Technology MIPI C-PHYSM And How It Enables Next Generation Display and Camera Implementations
- 8. © 2017 MIPI Alliance, Inc. MIPI CPHYSM Data Types 8 ANALOG DIGITAL A B C • 3 wires per lane • 3-level wires (LOW, MID, HIGH) • Every unit interval must contain LOW, MID, and HIGH wires • No two consecutive identical states Symbols (3 bits) Integers (16 bits) A>B B>C C>A Wire States (3 bits) Wire differential 7-symbol to 16- bit mapping Wires Wire states 6 5 6 3 4 6 5 3 6 -z -y -z -x +x -z -z-y -x 0 2 2 4 1 0 0 0 0x7290
- 9. © 2017 MIPI Alliance, Inc. Wire States 9 A B C A>B B>C C>A Wire state name HIGH LOW MID 1 0 0 +x LOW HIGH MID 0 1 1 -x MID HIGH LOW 0 1 0 +y MID LOW HIGH 1 0 1 -y LOW MID HIGH 0 0 1 +z HIGH MID LOW 1 1 0 -z ANALOG DIGITAL (3 bits) • A wire state is the collection of A, B, and C • 6 possible wire states
- 10. © 2017 MIPI Alliance, Inc. Symbols: Now We’re Transmitting! 10 • A symbol represents a transition between two wire states • 5 possible symbols Symbol (3 bits) Flip Rotate Polarity 0 0 0 0 1 0 0 1 2 0 1 0 3 0 1 1 4 1 DC DC Rotate 0 Decr. letter 1 Incr. letter Polarity 0 - 1 Toggle sign Flip 0 - 1 Same letter, toggle sign. -z+x Example: 1 +x-z Example: 3
- 11. © 2017 MIPI Alliance, Inc. Mapping 7 Symbols 16-bit Integers 11 • MIPI C-PHYSM defines a mapping between 7-symbol words and 16-bit integers Number of 7-symbol words: Number of 16-bit integers: 5" = 78125 2() = 65536 65536 7-symbol words 16-bit integers 65536 12589 unmapped words 1-to-1 mapping {0224100} 0x7290
- 12. © 2017 MIPI Alliance, Inc. Global Packet Transmission Similar to MIPI D-PHYSM 12 Start of Transmission Marker Preparation for HS Transmission HS-ZERO SoT 0 0 0 0 0 0 … 0 0 LP-11 LP-01 LP-00 1 11000 0 1 8-bit Word LP-111 LP-001 LP-000 D-PHYSM C-PHYSM 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 3 S 1 S 2 S 3 S 4 S 5 S 6 S 7 Data Payload 16-bit WordT3-PREBEGIN SYNC
- 15. © 2017 MIPI Alliance, Inc. • MIPI C-PHYSM defines a mapping between 7-symbol words and 16-bit integers Number of 7-symbol words: Number of 16-bit integers: 5" = 78125 2() = 65536 65536 7-symbol words 16-bit integers 65536 12589 unmapped words 1-to-1 mapping {0224100} 0x7290 MIPI C-PHY’s Magical Unmapped Words! 15 12589 unmapped words {3444443} {4444444} Sync Word (Alignment marker) Post (End-of-Packet marker)
- 19. © 2017 MIPI Alliance, Inc. Example: Alternate Low Power Mode 19 3 3 3 3 3 3 3 3 3 STOP 3 4 4 4 4 4 3 S 1 S 2 S 3 S 4 S 5 S 6 S 7 PREPARE ALP PAUSE STOP ALP PAUSE WAKE Frozen Wire State
- 20. © 2017 MIPI Alliance, Inc. Example: Alternate Low Power Mode 20 STOP LPDT COMMAND LPDT BYTEEME S 1 0 4 4 4 4 S 03 3 3 3 3 3 3 3 3 0 1 4 4 4 4 0 ALP PAUSE STOP ALP PAUSE WAKE PREAMBLE LPDT START LPDT NIBBLE Unmapped Word Unmapped Word
- 21. © 2017 MIPI Alliance, Inc. Unmapped Words Enable a Wide Range of Codes 21 Symbol Sequence ALP Function Code 0244440 Stop Code 0244441 ULPS Code 0244442 Trig 1 Code … … 4444444 Post2 Same functionality as legacy LP EME Sequences
- 23. © 2017 MIPI Alliance, Inc. SYNC Is an Unmapped Word • Five (5) possible SYNC words exist – 3444440 – 3444441 – … • First SYNC word in a burst is always 3444443 • Multiple SYNC words used to trigger different seed types for MIPI CSI-2SM scrambling 23
- 26. © 2017 MIPI Alliance, Inc. MIPI CSI-2SM Imaging Features Enabled by MIPI C-PHYSM • Long Reach Transport Efficiency (LRTE) – Easily delimits packets using unmapped words • ALPS – Helps maintain low voltage levels in advanced process nodes • Up to 32 Virtual Channels – Useful for imaging and vision applications supporting multiple sensor streams 26
- 27. © 2017 MIPI Alliance, Inc. MIPI CSI-2SM Imaging Features Enabled by MIPI C-PHYSM • Scrambling – Provides a wide range of seed triggers using multiple SYNC words • Future support for sensor fusion and camera commands – MIPI C-PHYSM natively enables future technologies for more efficient camera commands than those using legacy LP mode 27
- 29. © 2017 MIPI Alliance, Inc. MIPI DSI-2SM Features Enabled by MIPI C-PHYSM • Fast packets – Unmapped words enable very robust packet delimiting within a burst 29 Packet i Packet i+1 No Ambiguity
- 30. © 2017 MIPI Alliance, Inc. MIPI DSI-2SM Features Enabled by MIPI C-PHYSM • Display stream compression – Complete compatibility with compression needs 30
- 31. © 2017 MIPI Alliance, Inc. MIPI DSI-2SM Features Enabled by MIPI C-PHYSM • MIPI Display Command Set (DCSSM) Mode – Proven technology for buffered frame transmissions • Scrambling – Full support for scrambling at the protocol level 31