利用esp8266wifi信号强度测距

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向esp8266发送指令

1
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
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#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，

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