MIPI (Mobile Industry Processor Interface) is an interface standard developed by the MIPI Alliance. CSI is an interface standard specified by the Camera Working Group under the MIPI Alliance, which mainly consists of the application layer, protocol layer, and physical layer, and CSI-2 is channel scalable, supporting up to 4 channels of data transmission and single line transmission speed up to 1Gb/s.
To achieve higher video resolution and better image signal integrity, a combination of interface and device is essential. Devices such as retimers, adapter drivers and multiplexers for the MIPI protocol can help achieve flexible signal routing and better signal integrity, significantly extending the interface transmission distance.
MIPI CSI deserializer enables point-to-point transmission of large amounts of data
As the data rate in the interface increases, parallel buses become more problematic, and the increased number of channels makes layout more difficult. Large parallel buses consume valuable PCB substrate space, and deserializers bring a lower cost, lower power solution to large bit width parallel buses for point-to-point transfer of large amounts of data. This transfer is not only within the system, but also between systems.
The deserializer compresses the large bit-wide parallel bus into a differential serial link, and the output interface outputs the deserialized data. The STMIPID02 in the figure below integrates two MIPI CSI-2 receivers with 12-bit parallel output interfaces capable of outputting deserialized pixel data at rates up to 200 MHz.
(STMIPID02 MIPI CSI-2 Deserializer, ST)
Using this device, hosts with standard 8-, 10-, or 12-bit parallel input interfaces can be connected to a MIPI CSI-2 low-voltage, fully differential-bit serial, low-EMI interface, saving a significant amount of board-level space. Some vendors will integrate a voltage regulator on the deserializer to directly power the MIPI D-PHY receiver and core logic, which simplifies power management for the entire system.
High-performance retimers for better signal quality
High-performance retimers remove jitter and random noise from high-loss channels to achieve better signal quality. At high data rates, the retimers are optimized for long traces, connectors and cables to extend the signal transmission range and avoid signal integrity being compromised.
The most important thing is the jitter compensation capability. The level of adaptive equalization capability of the retimer will directly affect the compensation capability of the device. Generally speaking, to achieve the best jitter compensation effect, the adaptive equalization capability needs to be able to adjust dynamically. Take TI’s MIPI CSI-2 retimers as an example, with configurable equalizers at the input of the DPHY. The device compensates for PCB, connector and cable-related frequency losses and switch-related losses to provide optimal DP electrical performance between the CSI-2 source and receiver devices.
（SNx5DPHY440SS，TI）
Bandwidth and low power consumption is also important, a large enough bandwidth to present high resolution camera images after long distance transmission. Low power consumption since needless to say, especially for mobile applications, low power consumption is a prerequisite. High-performance retimers are optimized for mobile and consumer applications, and detection is done on the DPHY link so that the device switches to low-power
High resolution after MIPI CSI/DSI bridge conversionhttp://ebics.net/#contact
Both single- and dual-channel bridges are common, primarily converting video stream data from the output of a CSI or DSI processor to make it suitable for LVDS or eDP display panels with sufficient resolution.
（SN65DSI86，TI）
The rate per channel of these devices is certainly an important feature, as opposed to the size and power consumption of the device itself, which is still the first concern for designers when selecting a device. The device will be designed in accordance with industry standard interface technology, making it compatible with a wide range of microprocessors, and with a variety of power management features. Very typical is the MIPI definition of ultra-low power states (ULPS).
Summary
The MIPI protocol is still being gradually improved and gradually developed, not only in the cell phone industry, but also in the fields of drones, autonomous driving systems, intelligent robots, etc. MIPI protocols can now be seen. Especially in the field of robotics, the integration of the MIPI CSI protocol FPGA is very popular. To achieve better video resolution and better image signal integrity, the combination of interface protocols and high-performance devices is essential.
