Using 8266 as serial port debugging tool

There are students who do industrial control everyday , I must have had this experience , Some machines or equipment use serial communication, but debugging the real object is too troublesome or the cost is too high . At this time, if there is something that can simulate the equipment, it will be twice as much work . Generally speaking, the protocol of serial communication process is relatively simple , It's usually simple to send and receive . Looking for a circle of software serial ports on the Internet generally charges and uses drivers , Compatibility and use cost are relatively high .

There's just one in my hand CH340 Of USB Serial port and 8266, and 8266 Support network , So if you use a program to connect to 8266.8266 The tools responsible for forwarding serial port and network can not be debugged perfectly . Of course, it also expands the effect of direct remote debugging of equipment , and 8266+340 The cost is just 10 Yuan , Add a few lines of code to solve the problem perfectly .

This article only discusses the use of software simulation equipment . under these circumstances 8266 It's a transit , Read the serial port data from the upper computer software and forward it to and 8266 Network connected Software , At this time, the data sent by the upper level can be received on the software , At the same time, the software can make various responses , To test the correctness of the data processed by the host computer .

In order to facilitate testing and software connection , Here is the 8266 Of IP Write dead . The code is as follows ：

WiFi.mode(WIFI_STA);
    Serial.begin(115200);
    IPAddress local_IP(192, 168, 1, 166);
    IPAddress gateway(192, 168, 1, 1);
    IPAddress subnet(255, 255, 255, 0);
    // Set up 
    bool bConfigSucessed = WiFi.config(local_IP, gateway, subnet); // Set static IP

Then connect to wifi, Start a server to receive network connections .

// Global server , Listening port 9527
WiFiServer server(9527);

// Start server 
 server.setNoDelay(true);
 server.begin();

The process is relatively simple , Receive serial port data software to the connected network end , Receive network data software to serial port .

void loop()
{
    static WiFiClient client = server.available();
    if (!client)
    {
        client = server.available();
    }
    if (!client)
    {
        return;
    }

    client.setNoDelay(true);
    String comdata = "";
    char buf[101];
    while (Serial.available() > 0) //  The number of characters received by the serial port is greater than zero .
    {
        int size = Serial.read(buf, 100);
        buf[size] = '\0';
        comdata += buf;
        delay(2);
    }
    /****************** Serial port print data ************************/
    if (comdata != "") // If you receive data 
    {
        //Serial.println(comdata);
        client.print(comdata);
        client.flush();
    }

    while (client.available())
    {
        // Read client initiated TCP request 
        unsigned char len = 0;
        size_t readsize = client.readBytes((char *)&len, 1);
        //Serial.println(readsize);
        //Serial.println(len);
        if (len > 200)
        {
            client.stop();
            return;
        }
        char *buf = new char[len];
        readsize = client.readBytes(buf, len);
        buf[readsize] = '\0';
        String req = buf;
        delete[] buf;
        //Serial.println(req);
        if (req.startsWith("com:"))
        {
            //Serial.println("COM");
            String msg = req.substring(4);
            Serial.updateBaudRate(atoi(msg.c_str()));
        }
        else if (req.startsWith("send:"))
        {
            //Serial.println("SEND");
            String msg = req.substring(5);
            //Serial.println(msg.length());
            Serial.print(msg);
        }
    }
}

A minimalist protocol is implemented here , One was used byte To save the data length , Only... Can be received here 200 Data within , Of course, it can be extended , However, a message in general communication is less than 100 , Generally enough , You can also split long data into 200 Forwarding within . Also, only one client can be accepted here , If necessary, it can also be extended . thus 8266 It's basically working .