PID-product ID and vid-vendor ID of the USB device

According to the USB specification, all USB devices have a supplier ID (VID) and a product ID (PID). The host uses different vid and PID to distinguish different devices, both vid and PID are two bytes long. The supplier ID (VID) is applied by the supplier to the USB Forum. The vid of each supplier is unique and the PID is determined by the supplier. Theoretically, for different products, different models of the same product, and different design products of the same model, it is best to use different PIDs to distinguish different devices of the same manufacturer.

Vid and PID are usually stored in two modes: vid and PID of the master control manufacturer, which are stored in the bootcode of the master control, and vid and PID of the equipment manufacturer, the vid and PID are stored in the device firmware of the non-volatile storage device (EEPROM or flash) outside the master. When the USB device is connected to the host, if the firmware contains the vid and PID of the device manufacturer, the vid and PID are reported to the host, regardless of the vid and PID of the controller manufacturer. Therefore, in theory, the vid of a USB storage device should be the vid of the device manufacturer, rather than the vid of the master manufacturer. These two vids should be different (except for the devices produced by the master manufacturer ).

Because the duplicate vid and PID does not seriously affect the use of the product, many USB equipment manufacturers (most of the factory in shanzhai) do not apply for their own vid from the USB forum for convenience, but still follow the vid of the main control manufacturer or write vid and PID to the product at will. At the same time, the formal manufacturer only needs to apply for a vid. The PID is determined by the manufacturer, so there are products of the same model, different masters may be used (for commercial purposes, it is normal), and their PIDs are the same. Based on the above reasons, the vid and PID cannot accurately identify the master model of the USB device, you must pay attention to this problem when using USB devices.

USB device information viewing tool USB view http://download.csdn.net/detail/pzm/4116971 under windows.

 

USB cable transmits data to two computers