USB Hardware and Software Knowledge 4: wince USB driver terminology

To do USB-related things in wince, we must first understand some concepts, which is very important.

(1) host and Function
First, you must know that the USB is a master-slave structure. For PCs and mobile phones, the PC end is the master end, called the host, and the mobile phone is the slave end, usually called the client. However, this term has changed in wince. The master end is also called host, while the slave end is called function. Therefore, the corresponding drivers are called USB host driver and USB function driver. Here we need to remember the correspondence between the host and the function, rather than the client, which will be mentioned later.

(2) controller and client
For wince devices, it does not have the same function as a USB flash drive. It can be connected to a PC using USB cables in multiple forms. It can be a mass storage device ), it can also be represented as a NIC (rndis) and a serial device (Serial class). Therefore, a control system is required. wince separates this part and makes it a driver, it is called the controller. The driver at this layer controls the form of the wince device.

Then, the upper layer of the controller is the Client layer, which is commonly used in three categories: Mass Storage, rndis, and serial. When the wince device needs to behave in what form, it is converted by the Controller Driver (unmount the old client and load the new client ). The device is called function, so the full names are USB function controller driver and USB function client driver.

 

In fact, the host end also has the Controller layer, which is not studied here. It is suggested that when the device side shows different forms, the PC side also needs to show different forms and correspond to them, so a controller is also required. Note: The host and client here are different from the common concepts. You can understand this point from multiple perspectives.

(3) MDD has been implemented by Microsoft. For Windows Mobile, the source code/public/common/oak/Drivers/usbfn/controller/MDD. Generally, the hardware BSP provider is responsible for providing the PDD part, the controller driver is for the USB bus on the device. USB function client driver can be divided into mass storage, rndis, and serial. Microsoft has also implemented this function. The source code is in/public/common/oak/Drivers/usbfn/class.

(4) Windows Mobile windows 5.0 and windows do not provide the form of loading the USB client into the mass storage (you can attach an external memory card, such as a TF card, to a Mobile Disk on a PC, such as a USB flash drive), you can manually add a software switching tool.

Http://hi.baidu.com/donghaozheng/blog/item/3b2806faf2afc99058ee903b.html ()