The definition of the USB camera interface mainly involves aspects such as the physical connection, electrical characteristics and data transmission protocol of the USB interface. The following is a detailed explanation of the definition of the USB camera interface:
First, the physical connection of the USB interface
Interface Type: USB cameras typically use standard USB interfaces, including USB Type-A, USB Type-B, USB Type-C, atď. Among them, the USB Type-A interface is the most common interface Type and is usually used to connect to the computer host. The USB Type-B interface is often used to connect devices such as printers and scanners; The USB Type-C interface is a new Type of interface. It supports forward and reverse plugging and has a higher data transmission speed and stronger power transmission capacity.
Pin definition: The USB interface contains multiple pins for transmitting data, power, and ground wires, atď. For a USB camera module, usually only a few of the pins need to be used. For example, the red pin is usually used to connect the positive terminal of the power supply (VCC or 5V), the black pin is used to connect the ground wire (GND), and the green and white pins are used for DATA transmission (DATA+ and DATA-).
Second, electrical characteristics
Voltage and current: The USB interface typically provides a 5V DC power supply, and the current varies depending on the device. For USB camera modules, their working current is usually between several hundred milliamperes and one ampere.
Power limit: To ensure the stability and security of the USB interface, the USB standard has imposed power limits on devices. For the USB 2.0 interface, the maximum power of a single device is usually 500 milliwatts (5V * 100mA); For the USB 3.0 interface, the maximum power can reach 900 milliwatts (5V * 180mA) or higher.
Third, data transmission protocol
UVC protocol: USB cameras typically use the UVC (USB Video Class) protocol for data transmission. UVC is a universal USB camera interface standard that enables camera devices to be compatible with various operating systems and achieve plug-and-play functionality. Through the UVC protocol, the camera can transmit video data in the form of streams to the computer for processing and display.
Data transfer rate: The data transfer rate of the USB interface varies depending on the version. For example, the maximum data transfer rate of the USB 2.0 interface is 480Mbps (60MB/s); The maximum data transfer rate of the USB 3.0 interface can reach 5Gbps (625MB/s) or higher. For the USB camera module, its actual data transmission rate is also affected by factors such as the camera resolution and frame rate.
Fourth, interface compatibility
Operating system compatibility: Due to the support of the UVC protocol, USB cameras can usually achieve plug-and-play functionality on multiple operating systems, including Windows, Mac OS, Linux, atď.
Device compatibility: The USB camera interface also has a certain degree of device compatibility. As long as the device meets the requirements of the physical connection, electrical characteristics and data transmission protocol of the USB interface, the connection and data transmission with the USB camera can be achieved.
In conclusion, the definition of the USB camera interface covers aspects such as physical connection, electrical characteristics, data transfer protocols, and interface compatibility. These definitions ensure that USB cameras can achieve stable connections and data transmission with various computers and devices.