MIPI CSI Interface learning notes

Camera Serial Interface (CSI-2) sensors in embedded designs - BY TED MARENA

http://www.electronicproducts.com/Digital_ICs/Communications_Interface/Camera_Serial_Interface_CSI-2_sensors_in_embedded_designs.aspx

The majority of cameras in high volume consumer products, such as smartphones and tablets, use MIPI (Mobile Industry Processor Interface)-based sensors. The most commonly used interface for this type of image sensor is the CSI-2 specification (Camera Serial Interface). CSI-2 consists of a unique physical bus that contains a differential clock and from one to four differential data lanes. This interface is called a D-PHY. What makes the D-PHY unique is that it can change “on the fly” from differential to single-ended signaling. High Speed (HS) mode is differential and single-ended mode is called low power (LP). For an high performance video from a CSI-2 image sensor will use the HS differential data mode.

The CSI-2 HS interface operates electrically as a SLVS (scalable-low-voltage-signaling) standard device with a 200 mV common mode voltage. The clock is DDR source synchronous and the number of data lanes for a CSI-2 interface can vary from one to four lanes. Each data lane transmits 8-bit serial data. The higher the image sensor resolution and frame rate the more data lanes, and higher speed for each, will be required. The practical limit for a CSI-2 interface is less than 1 Gbits/s data rates, but often it is less than 700 Mbits/s. For example, a high definition 1080p60 video signal would be transmitted with four differential data lanes, each running up to about 500 Mbits/s. Figure 1 shows a typical block diagram.

In many of these applications the CSI-2 image sensor would be configured at power up and set to transmit the frames in HS mode continuously. This is free running clock mode or fixed high-speed mode.

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http://www.petervis.com/Raspberry_PI/Raspberry_Pi_CSI/Raspberry_Pi_CSI-2_Connector_Specifications.html

http://www.petervis.com/Raspberry_PI/Raspberry_Pi_CSI/Raspberry_Pi_CSI_Camera_Interface.html

http://www.petervis.com/Raspberry_PI/TTL_to_CMOS_Logic_Level_Converter/TTL_to_CMOS_Logic_Level_Converter.html