Learning Linux bus driver with cainiao first knowledge of USB mouse packet capture data

Little Japan has snatched the Diaoyu Islands for the time being. However, we believe that with the concerted efforts of the people throughout the country, the Diaoyu Islands cannot be escaped. As for whether to use force or not, we have no say. It is better not to use force. The victim will still be the boss's surname at that time. I believe that time will explain everything. Here we can only pray silently, and the Diaoyu Islands will return to the embrace of the motherland and Mainland as soon as possible.

Well, the Diaoyu Islands is a matter of concern, but it cannot help you. Instead, you should learn more and contribute to the construction of the motherland.

I remember that I didn't go into depth after talking about some basics of USB last time. I was very busy last week and I was not doing anything this week. After summing up some of the SPI and I2C lessons, now we can start USB. After I have a certain understanding of its system structure, device descriptors, and data transmission methods, I must know specific data, flowcharts, and so on, in this way, we can better understand it. Let's take a look at the figure below.

 

 

Let's take a look at the figure above. I believe this figure is easy to understand? Well, are you familiar with it? Next, let's introduce it. The company has a USB analyzer, but it has never been used. This is very expensive. It is also very easy to use. After inserting the line, set some functions. Click "run" and click "OK". Then, the above figure is displayed. It is embedded in State-owned documents, and the company's things are not easy to use.

USB data is composed of binary numeric strings. First, numeric strings constitute a domain (which has seven types). Then, the domain forms a package, and the package forms a transaction (In, out, setup ), transaction final composition transmission (Interrupt transmission, parallel transmission, batch transmission and control transmission ).

 

1. Transmission (interrupt, batch, synchronization, and control)

The transfer here is the transmission method, which controls the transmission get and obtains the descriptor.

This is also transfer, which controls the transmission set and sets the address.

 

2. Transactions (In, out, setup)

This is a setup transaction.

This is an in transaction.

This is the out transaction.

 

3. Packet (token package (Setup), data packet (data), handshake packet (ACK), and special packet)

This is the package in the setup transaction. As you can see from Dir, there are hostà device and device à host.

 

4. domain (Sync), Id domain (PID), address domain (ADDR), End Point domain (endp ),

Frame number domain (FRAM), data domain (data), verification domain (CRC ))

In the above figure, we can see sync, ADDR, crc5, data, and other fields.

 

Therefore, the domain constitutes a packet, and the packet constitutes a transaction, and the transaction constitutes a transmission. I believe this explanation can be understood a lot for the USB protocol.