EEVblog Electronics Community Forum

Products => Computers => Topic started by: DiTBho on May 15, 2022, 01:51:04 pm

Title: RPI + HDMI2CSI: does it work? and what does work?
Post by: DiTBho on May 15, 2022, 01:51:04 pm

The company "Geekworm" has an interesting toy for RPI: the C779!

It's a "camera serial interface(1)" version2, aka "CSI-2" Module with Toshiba TC358743XBG chip that accepts HDMI input up to 1080p@25fps and allows RPI(2) to capture and record videos though the v4l2-ctl  console tool.


Any experience?  :-//



(1) The Camera Serial Interface (CSI) is a specification of the Mobile Industry Processor Interface (MIPI) Alliance. It defines an interface between a camera and a host processor. The latest active interface specification is CSI-3 which was released in 2012.
 
Different Standards of MIPI CSI Interface:

• MIPI CSI-1 was the original standard MIPI interface for cameras. It emerged as an architecture to define the interface between a camera and a host processor.
• MIPI CSI-2 released in 2005. It uses either D-PHY or C-PHY (Both standards are set by the MIPI Alliance) as a physical layer option. The protocol is divided into the following layers:
  1. Physical Layer (C-PHY/D-PHY)
  2. Lane Merger Layer.
  3. Low Level Protocol Layer.
  4. Pixel to Byte Conversion Layer
  5. Application Layer
  
  Features:
  PHY variants supported: D-PHY 1.2, C-PHY 1.0 or "Combo PHY"
  Number of Virtual Channels: Four (4)
  Control Interface: I2C
  Line based transmission (Easy implementation, low gate count, matched data rates for sensor and link)
  Interrupt type: In-Band
  Supports { RGB, RAW, YUV, JPEG }
  Embedded Data
  CRC/ECC for payload & Header Protection
  
• MIPI CSI-3 is a high-speed, bidirectional protocol primarily intended for image and video transmission between cameras and hosts within a multi-layered, peer-to-peer, UniPro-based M-PHY device network. Originally released in 2012, got re-released in version 1.1 in 2014.
  

(2) compatible with: Raspberry Pi { 4B, 3B+, 3B, 3A+, 2B, 2B+, Pi Zero , Zero W }

Title: Re: RPI + HDMI2CSI: does it work? and what does work?
Post by: DiTBho on May 15, 2022, 01:51:47 pm

Has anyone already tried to connect VGA through a VGA-to-HDMI-adapter?

Code: [Select]

vga ----> VGA-to-HDMI (adapter) ----> HDMI-to-CSI-2 (C779) ----> RPI V4L
Does it work correctly?

Title: Re: RPI + HDMI2CSI: does it work? and what does work?
Post by: DiTBho on May 15, 2022, 04:34:42 pm

Digging deeper, I found that C779 only supports video, doesn't support audio, but there are other modules(1) that take the incoming HDMI signal and converts it into a separate CSI signal and I2S audio signal.

I2S-Audio requires wiring to the expansion port of the RPI

(1) { C780, C790 }