利用esp8266wifi信号强度测距

水深无声 2022-05-31 12:15 1249阅读 0赞

![这里写图片描述][70]  
向esp8266发送指令

AT + CWLAP

可以得到当前可加入wifi信号的信息，其中包括的rssi，就是我们所需要的。  
提取出rssi，然后带入公式

d = 10^((abs(rssi) - A) / (10 * n))

即可得到接收机和发射机之间的大概距离。  
效果图  
![这里写图片描述][70 1]

#include "reg52.h"
    #include "string.h"
    #include "math.h"
    
    typedef unsigned int uint;
    typedef unsigned char uchar;
    
    #define NAME 9 //xutianyun
    #define N 40 //N = 10 * n ,其中n为环境衰减因子，3.25-4.5
    #define A 51 //接收机和发射机间隔1m时的信号强度
    
    int rssidata = 0;
    uchar recbuffer[32];
    uint cnt = 0;
    uint getit = 0;
    uint datalen = 0;
    uchar wifi_rssi[5];
    uchar wifi_ssid[11] = {
       '"','x','u','t','i','a','n','y','u','n','"'};
    float d;
    uint dis;
    uchar temp;
    
    void UsartInit(void)    {
       SCON = 0x50;
       TMOD = 0x20;
       PCON = 0x80;
        TH1  = 0xF3;
        TL1  = 0xF3;
       ES   = 1;
       EA   = 1;
        TR1  = 1;
    }
    
    void SendUart(uchar value)  {
       ES = 0;
       SBUF = value;
        while(!TI);
       TI = 0;
       ES = 1;
    }
    
    void SendString(uchar *str) {
        while(*str != '\0') {
            SendUart(*str);
            str++;
        }
    }
    
    float rssiTodis(int RSSI) {
        float iu, distance;
        iu = (float)(RSSI - A) / (float)N;  
        distance = pow(10, iu);
        return distance;
    }
    
    void main() {
        UsartInit();
        while(1);
    }
    
    void Usart() interrupt 4 {
        uchar rec;
        if(RI != 0) {
            rec = SBUF;
           RI = 0;
        }
        if(rec == '"')  {
            cnt = 1;
            getit = 0;
        }
        else if(rec == ',') {
            cnt = 0;
            datalen = 0;
            if(getit == 1)  {
                SendUart(wifi_rssi[1]);
                SendUart(wifi_rssi[2]);
                SendString("\r\n");
                rssidata = (wifi_rssi[1] - '0')* 10 + (wifi_rssi[2] - '0');
    
                d = rssiTodis(rssidata);
                dis = d*10000;  
                temp = dis/10000 + '0';
                SendUart(temp);
                temp = dis/1000%10 + '0';
                SendUart(temp);
                temp = dis/100%10 + '0';
                SendUart(temp);
                temp = dis/10%10 + '0';
                SendUart(temp);
                temp = dis%10 + '0';
                SendUart(temp);
                SendString("\r\nok\r\n");
    
            }
        }
        else if(rec == '-') {
            if(strncmp(recbuffer, wifi_ssid, NAME + 2) == 0)    getit = 1;
        }
    
        if(cnt == 1)    {
            recbuffer[datalen++] = rec;
        }
        if(getit == 1) {
            wifi_rssi[datalen++] = rec;
        }
    }

注：以上代码烧录单片机后，需要借助串口调试助手，

[70]: /images/20220531/697ae1ad79a942bfbc2456e156e42f3e.png
[70 1]: /images/20220531/acde96ebece8446aa8ef8f89d61f7200.png