12/16/2020

MIPI(Mobile Industry Processor Interface)

1. MIPI(Mobile Industry Processor Interface)

MIPI Aliance는 ARM, Intel, Nokia, Samsung, STMicroelectronics and Texas Instruments 회사들이 만든  Mobile 관련된 Interface로 2003년에 처음 생성되었다고 한다.
그리고, 위에서 보았듯이 Mobile용으로 탄생했기 때문에 초반에 대중적으로 많이 사용되어지지 않았다. 

주로 사용되는 곳들은 Display 와 Camera 와 Baseband 부분인 것으로 보이며, 이외 것들은 아래의 링크로만 해둔다. 

MIPI Aliacne의 Spec 확인 

MIPI-CSI

MIPI-DSI

MIPI-DPI

MIPI-SPMI

C-PHY
D-PHY
M-PHY


1.1 MIPI 의 기본용어 정리 및 기본이해 

  • MIPI LP/HS 동작 
  1. Low power transmitter: LP-TX
  2. Low power receiver: LP-RX
  3. High-speed transmitter: HS-TX
  4. High-speed receiver: HS-RX
  5. Low-power competition detector: LP-CD

  • MIPI의 Lane type
Clock lane 과 Data lane  구분해보면 되고 , Data Lane로 다시 두 가지로 나뉘어진다.

One-way clock lane: 단방향 clock lane 
  • Master：HS-TX, LP-TX
  • Slave：HS-RX, LP-RX
Two-way data lane (lane0): 양방향 Data lane
  • Master, Slave：HS-TX, LP-TX, HS-RX, LP-RX, LP-CD
One-way data lane (lane1-lane3): 단방향 Data lane
  • Master：HS-TX, LP-TX
  • Slave：HS-RX, LP-RX

  • Low power mode (Low-Power LP mode)
used for control: maximum 10MHz, only use data lane0 (clock is XOR from CP and CN).
LP Mode라고 부르며, 재미 있는 것은 data lane0을 사용을 하며, clock lane과 XOR를 하여 동작하며, 이 Data Lane은 differential 로 동작하지 않는다. 

  • High-speed mode (High-Speed ​​HS mode) 
high-speed data transmission: 80M-1Gbps/lane.
HS Mode라고 하며 differential 로 동작하며, Level로 다르다. 


https://www.programmersought.com/article/7481201221/


  • State of Lane
  1. LP-00, LP-01, LP-10, LP-11 (single-ended)
  2. HS-0, HS-1 (differential)
LP와 HS State는 아래의 값에의해 결정이 되며 이는 Lane의 상태와 Command라고 생각하면 되겠다. 

https://www.programmersought.com/article/7481201221/




1.2 MIPI Operation Mode   
 

  • Three operating modes of Data Lane 
  1. Escape mode, 
  2. High-Speed(Burst) mode
  3. Control mode
아래 그림을 보면 쉽게 이해가 감 

Possible events starting from the stop state of the control mode are:
Control Mode 상태가 종료되어 events가 가능한 상태이며, LP11를 이용하여 STOP 후 진행 
  1. Escape mode request (LP-11→LP-10→LP-00→LP-01→LP-00)
  2. High-Speed mode request (LP-11→LP-01→LP-00)
  3. Turnaround request (LP-11→LP-10→LP-00→LP-10→LP-00)

BTA: Bus Trunaround / Trunaround  의미 

  • Escape mode State 
Escape mode is a special operation of data Lane in LP state 
    - In this mode, you can enter some additional functions: LPDT, ULPS, Trigger

• Data Lane enters Escape mode through LP-11→LP-10→LP-00→LP-01→LP-00
• Once in Escape mode, the sender must send an 8-bit command in response to the requested action
• Escape mode uses Spaced-One-Hot Encoding

  • Ultra-Low Power State
  1. In this state, lines are empty (LP-00)
  2. The ultra-low power state of the clock Lane
  3. Clock Lane enters the ULPS state through LP-11→LP-10→LP-00
  4. Exit this state through LP-10 → TWAKEUP → LP-11, the minimum TWAKEUP time is 1ms

  • High-speed data transmission
  1. The act of sending high-speed serial data is called high-speed data transmission or burst
  2. All Lanes doors start synchronously, and the ending time may be different.
  3. The clock should be in high-speed mode

  • The transmission process under each mode of operation
  1. The process of entering Escape mode: LP-11→LP-10→LP-00→LP-01→LP-00→Entry Code → LPD (10MHz)
  2. The process of exiting Escape mode: LP-10→LP-11
  3. The process of entering high-speed mode: LP-11→LP-01→LP-00→SoT(00011101) → HSD (80Mbps ~ 1Gbps)
  4. The process of exiting high-speed mode: EoT→LP-11
  5. Control mode-BTA transmission process: LP-11→LP-10→LP-00→LP-10→LP-00
  6. Control mode-BTA receiving process: LP-00→LP-10→LP-11






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