Preface
- Recently, with the help of ZR’s FAE friends Duan and Kang and others, Master Hung completed the PD fast charging, Only Source software, this huge project. So far, the compatibility is pretty good, and all the laptop phones tested have no problems. Master Hung can only look up to the skills they possess. . . . Thanks to the party, let me know these NB people.
The buck chip used by the master is ZR's SW3526 , ON Semiconductor's FUSB302 physical layer chip, and an STM32F103 MCU.
Master Hung says business
The last chapter talked about the type-c connection, so what should I do when connected, the smart little boss thought, we are about to start drawing teacher cang (implement the PD strategy).
After the connection is connected, it should be used as the source to detect the Emark line "5A line", or broadcast the source cap. As a sink, it should wait to receive the Source cap and make a Request.
First of all, we need to know what the data format of the PD protocol looks like:
as shown in the figure above, only the message is the protocol layer, and the others are the physical layer data.
PD physical layer
The physical layer that the big brother understands: If we want to draw the teacher, then we must have a drawing board and a paintbrush. Then the drawing board is used to put data, assemble data, and transmit data. The paintbrush is used for encoding.
The physical layer is responsible for these contents, including the assembly of data. It takes the message, adds the preamble, SOP, CRC, EOP, etc., and then encodes and transmits it. Then the received data is the opposite, decoded, verified, and then Take out the message.
When doing software or learning, the physical layer is the most critical, and what you need to know clearly is the SOP .
SOP
SOP: start of packet. The beginning of the package.
We can see the introduction to SOP in the keyword explanation part of the PD standard, Chapter 2.5, and 5.6.1.2. But I know that many students are not too cold with English. So here is a popular explanation. Speak my understanding.
There are three types of SOP:
First of all, SOP, SOP', SOP'' all indicate the beginning of a data packet.
The first information obtained from the keyword:
SOP is to interact with the port, then we need the SOP type;
SOP' and SOP'' both indicate the type required for data interaction with the cable plug.
Then there are the thematic explanations of 2.5 and 5.6.1.2 in the standard:
The role of SOP
SOP is similar to the address when communicating with IIC. If multiple slaves are connected to one master, then the address is needed to distinguish, and the master is communicating with whom.
It can also be said that a certain local tyrant has 100 beauties in the same building, so the local tyrant should come to them according to the school number and decide which beauty to have sex with at night.
For PD, SOP is the device address of IIC, or the house number of the local tyrant.
SOP
SOP refers to the communication between the source and the sink, and SOP'/SOP'' both mean to communicate with the cable. Separate three categories, or three addresses, so that conflicts can be avoided. It is equivalent to a bus arbitration mechanism.
SOP can only communicate end-to-end (source and sink), and the cable cannot recognize such messages.
SOP '/ SOP' '
SOP'/SOP'' can only be a data type that one end (Source/Sink) communicates with the cable. And the SOP'/SOP' type of data that needs to be noted can only be initiated by Source or Sink, and the cable can only respond passively. Whether it is initiated by source or sink depends on whether the source supplies power to the cable or the sink supplies power to the cable (Vconn's power supply). If the Vconn's power supply is the source end, then SOP'/SOP'' type Data can only be initiated by the source, the cable recognizes and responds, and the sink cannot do any response actions.
Only the Emark line has this communication capability.
Then some students noticed why it is divided into SOP' and SOP'.
Master Hung’s understanding: The standard document states that an EMARK line must have SOP' type communication capabilities, but SOP' is not necessarily. In addition, we all know that the Emark line or PD is based on the line with both ends of the C port, then this SOP'/SOP'' is on these two ends, and this will not change, that is, the hardware is fixed, one end SOP', the other end is SOP'' (or none).
There is another message that says: When SOP' type PD data packet is communicating with other cable plugs, you can use SOP'' data packet to communicate with another cable plug to avoid conflict. Look at the picture below:
Master Hungry mainly does power-related content and does not pay attention to PD's processing of data transmission. So I personally feel that this SOP is a spare tire.
If you have any different opinions, you can leave a message to discuss or private message to discuss. Deduction QUN seven one seven seven two zero two one ba.
In addition, there is a picture attached to the PD standard, which can help everyone understand.
From the above picture, it means that SOP' is the communication between Vconn source and one end of the cable, and SOP' is the communication with the other end. But everyone pays attention to two points, 1. SOP'/SOP'' does not distinguish between the near end and the far end (in the picture, SOP' is the near end of the Vconn source, and SOP'' is the far end);
2. Many Emark lines may not Support SOP''.
Wow, it's 12 o'clock. Today seems to be a lot of writing. The next master Hungarian meeting will start to talk about the PD protocol layer.
Today’s sharing is here, I hope everyone can pay attention, like, and comment. . . . Don't prostitute for nothing.
QUN Seventeen Seven Seven Two Zero Two One
Seven QUN Seven Seven Seven Seven Seven Zero Two One N