WiFi smartconfig implementation

Many devices now use mobile phones directly wifi To configure the , There is no operating interface for the device , image TISmartConfig,Airkiss.

There are also many descriptions on the Internet , I have also realized , Overall, it is relatively simple .

Device end , Need to be able to support wifi Mixed mode , Basically .

The process of implementation is to pass the data to be sent through udp The length of the packet , The device is in mixed mode , By fetching udp The radio bag , according to 802.11 Filter the features of , Just find the package of the custom protocol , Lock specific ＭＡＣ After the address , Continuous packet capturing , Just parse it out , It's simpler .

Definition of agreement

Generally, a protocol header is defined , If used 0x1,　0x４,　0x8, In this way, the device side is grasping ＵＤＰ Packet time , After seeing such a packet length rule , It is considered as a package header , You can add another Baotou ＣＲＣ８ check , this ４ Bytes , As ＵＤＰ The length of the package , Continuous transmission .

The test is general ３,４ A continuous ＵＤＰ Chances of being out of order , It's not that big , In this way, you can quickly lock the start of the protocol .

 

Code the data , There are many general data , Expect to send continuously ＵＤＰ, Can receive continuously in sequence , It's unrealistic . Therefore, each data byte , Recode , Here's what I did , Each node uses ４ Two bytes to encode , such :

Forerunner | Data serial number | data |CRC8　

The first byte is fixed to 0xc, Indicates the beginning of a byte , The second byte represents the sequence number of the data byte , The third byte is the real data , The fourth byte is ＣＲＣ check ： To the front ３ Bytes for verification , The receiving end can judge whether it is normal .

That is, you need to send a string to the device , Such as : “12345678”, Express ＷＩＦＩ Connection password , Then you need to send 4*8＝３２ individual ＵＤＰ The datagram , Because every data is numbered , In this way, different data can be verified and received multiple times , The success rate is very high .

Send another... In the data ＣＲＣ Verification of data , Verify the received data again .

       Can be like Airkiss Also send one ＳＳＩＤ Of ＣＲＣ check , Verify found ＳＳＩＤ Is it really to be configured ＳＳＩＤ, I feel a little superfluous .

       Can be like Airkiss Send a random number , Used when the equipment end is connected ＷＩＦＩ when , Notify the user for configuration , The device is already connected through your data connection .

       Generally like WIFI Data like passwords , The relatively small , Tested it , It's done in a few seconds .