MIPI camera interface vs USB camera interface:How should one choose?

Over the past two years, with the rapid development of artificial intelligence (AI) vision, automation, and mobile devices, the embedded vision field has placed increasingly higher demands on camera performance and integration. However, despite technological advancements, MIPI and USB interfaces remain the two most popular interface types for most embedded vision applications.

This article will delve into the definitions, features, advantages, and disadvantages of MIPI and USB camera interfaces, and through a detailed comparison, provide you with a practical selection guide to help you find the most suitable camera solution for your specific project.

A MIPI camera is essentially a camera module that uses the MIPI CSI protocol to communicate between the camera sensor and the main processor. The MIPI CSI protocol is specifically designed for high-speed, efficient, and scalable communication, making it an ideal choice for applications requiring high-quality image capture. USB cameras, on the other hand, transmit data via a USB interface. Let's take a closer look at the different types and functions of MIPI and USB interfaces.In the previous article, we have briefly understood mipi and usb interfaces.

mipi camera and usb camera

MIPI is currently the most commonly used camera interface for point-to-point image and video transmission between cameras and host devices. Its advantages lie in its ease of use and ability to support a variety of high-performance applications. In addition, it offers powerful features such as 1080p, 4K, 8K, and higher resolution video and high-resolution imaging.

The MIPI CSI-2 (MIPI Camera Serial Interface 2) standard interface is characterized by high performance, cost-effectiveness, and ease of use. It offers a maximum bandwidth of 10 Gb/s and features four image data channels, each with a data transfer rate of up to 2.5 Gb/s. MIPI CSI-2 is faster than USB 3.0 and has a reliable protocol capable of handling video resolutions from 1080p to 8K and beyond. Additionally, due to its low power consumption, MIPI CSI-2 offers higher net image bandwidth.

The MIPI CSI-2 interface, with its multi-core processor, consumes fewer CPU resources. It is the default camera interface for Raspberry Pi and Jetson Nano. The Raspberry Pi Camera Module V1 and V2 are also based on this interface.

MIPI CSI-2 typically outperforms USB 3.0 in terms of speed and provides a reliable protocol for handling video resolutions ranging from 1080p to 8K and beyond. Additionally, since MIPI cameras are directly connected to the device's image signal processor (ISP), they generally offer superior image quality, lower latency, and better synchronization. Their low overhead and support for multi-core processors typically result in reduced CPU resource consumption.

MIPI interfaces are not typically recommended for applications requiring long cables, as their capabilities are limited beyond 30 cm. MIPI CSI-2 requires specialized components, which can increase the cost of embedded systems. It also typically requires additional drivers and specific hardware interfaces, making integration more challenging, especially for developers unfamiliar with MIPI standards.

A USB interface is generally the connection point between two systems (camera and PC). Known for its plug-and-play functionality, the advantage of choosing a USB interface lies in the fact that it does not require the expensive and time-consuming development cycle and costs associated with embedded vision interfaces. Older versions of USB 2.0 have gradually declined due to their obvious technical limitations and have become incompatible with many components. The introduction of USB 3.0 and USB 3.1 Gen 1 interfaces was aimed at overcoming the limitations of USB 2.0 interfaces.

usb20 interface

The USB 3.0 (and USB 3.1 Gen 1) interface combines the advantages of different interfaces, including plug-and-play compatibility and low CPU load. The USB 3.0 visual industrial standard also improves its reliability for high-resolution and high-speed cameras.

It requires minimal additional hardware and supports low bandwidth-up to 40 megabytes per second. The maximum bandwidth reaches 480 megabytes per second. It is 10 times faster than USB 2.0 and 4 times faster than GigE! Its plug-and-play functionality also ensures that embedded vision devices can easily replace damaged cameras.

usb30 interface

Due to the bandwidth limitations of the USB standard, the biggest drawback of USB 3.0 interfaces is that they cannot run high-resolution sensors at high speeds. Another drawback is that the cable can only reach a maximum distance of 5 meters from the main processor. In addition, additional data processing and protocol overhead may result in higher latency. The compatibility of these cables with industrial cameras must be checked on a case-by-case basis.

To better understand the differences between MIPI and USB camera interfaces, the following table summarizes their key differences:

	MIPI camera	USB camera
Data transfer speed/bandwidth	higher, with MIPI CSI-2 reaching up to 10 Gbps (4 channels)	Lower, limited by USB standards (USB 2.0: 480 Mbps; USB 3.0: 5 Gbps; USB 3.2 Gen 2x2: 20 Gbps; Thunderbolt 3/USB 4: 40 Gbps)
power consumption	Lower	Higher
Compatibility and integration difficulty	Requires specific hardware and drivers, and is more complex to integrate.	Widely compatible with various devices and operating systems, plug-and-play, and easy to integrate.
Transmission distance	Short, usually limited to within 30 cm	Long, USB 2.0/3.0 can reach up to 5 meters
Cost	Usually higher, as it requires specialized components and design	Usually lower, more economical
Image quality and latency	Usually higher, lower latency, direct connection to ISP	May have latency issues, lower image processing efficiency
Multi-camera compatibility	Supports multi-camera configurations using multiple channels and virtual channels	Depends on USB hubs and system resources

GMSL is another popular interface, typically used as an alternative to MIPI and USB, especially when image data needs to be transmitted over distances greater than 3 meters.

Of course, if you are not sure how to choose the right camera module, please visit How to Select the correct camera Module for an Embedded vision system.

Whether to choose MIPI or USB camera interface ultimately depends on the specific requirements and priorities of your project. Here are some key decision factors:

If your project requires ultra-high resolution, high frame rate, and low latency image transmission, such as robot AI vision equipment or industrial inspection systems, MIPI cameras are the better choice. Its high bandwidth and direct connection to the ISP ensure optimal performance. For simple, low-speed image applications, USB cameras are typically sufficient and easier to deploy.

If your device is battery-powered or has strict energy efficiency requirements, MIPI cameras offer an advantage due to their low-power design. USB cameras typically consume more power and may not be suitable for power-sensitive applications.

If you prioritize plug-and-play functionality, broad compatibility, and rapid deployment, USB cameras are the ideal choice. They are compatible with most devices and operating systems and have lower integration complexity. MIPI cameras, however, require specialized hardware and driver support, making the integration process more complex and requiring higher technical expertise, making them more suitable for teams with embedded system development experience.

If the camera needs to be connected to the main processor over a longer distance, USB cameras (with a maximum distance of 5 meters) have an advantage. MIPI cameras are typically limited to short-range connections (within 30 centimeters) and are suitable for compact systems where the camera is located close to the processor.

USB cameras are generally more cost-effective and, due to their broad compatibility, may not require a dedicated processor, thereby reducing overall system costs. MIPI cameras may involve higher upfront costs as they require specialized components and more complex designs.

If your host system is based on an ARM platform (such as NVIDIA Jetson, TI Jacinto TDA4VM, or NXP i.MX), MIPI cameras will integrate seamlessly. If your host system is based on an x86 platform, USB cameras are the more suitable choice.

In embedded vision applications, the choice of camera interface is important. Therefore, we need to make a reasonable choice between MIPI and USB. Of course, there are many other interfaces to choose from besides these two, but in most cases, either MIPI or USB is sufficient.