09.ESP8266 WiFiScan库的使用

现在,通常,为了让手机连上一个WiFi热点,基本上都是打开手机设置里面的WiFi设置功能,然后会看到里面有个WiFi热点列表,然后选择你要的连接上。 基本上你只要打开手机连接WiFi功能,都会发现附近有超级多的各种来路不明的WiFi热点(连接有风险需谨慎),那么手机是怎么知道附近的WiFi的呢?
    通常,无线网络提供的WiFi热点,大部分都开放了SSID广播(记得之前博主讲过WiFi热点也可以隐藏的),Scan WiFi的功能就是扫描出所有附近的WiFi热点的SSID信息,这样一来,客户端就可以根据需要选择不同的SSID连入对应的无线网络中。

一般扫描网络需要几百毫秒才能完成。
    而扫描WiFi过程包括:

  • 触发扫描过程
  • 等待完成
  • 提供结果

那么Scan WiFi库提供了两种方式实现上面的扫描过程:

  1. 同步扫描:通过单个函数在一次运行中完成,需要等待完成所有操作才能继续运行下面的操作。
  2. 异步扫描:把上面的过程分成几个步骤,每个步骤由一个单独函数完成,我们可以在扫描过程中执行其他任务。

扫描操作方法

同步扫描周边有效wifi网络

/**
 * Start scan WiFi networks available
 * @param async         run in async mode(是否启动异步扫描)
 * @param show_hidden   show hidden networks(是否扫描隐藏网络)
 * @param channel       scan only this channel (0 for all channels)(是否扫描特定通道)
 * @param ssid*         scan for only this ssid (NULL for all ssid's)(是否扫描特定的SSID)
 * @return Number of discovered networks
 */
int8_t scanNetworks(bool async = false, bool show_hidden = false, uint8 channel = 0, uint8* ssid = NULL);
//实例代码 这只是部分代码 不能直接使用
//同步扫描
int n = WiFi.scanNetworks();//不需要填任何参数
Serial.println("scan done");
if (n == 0) {
    Serial.println("no networks found");
} else {
    Serial.println(" networks found");
}

异步扫描周边有效网络

/**
 * Start scan WiFi networks available
 * @param async         run in async mode(是否启动异步扫描)
 * @param show_hidden   show hidden networks(是否扫描隐藏网络)
 * @param channel       scan only this channel (0 for all channels)(是否扫描特定通道)
 * @param ssid*         scan for only this ssid (NULL for all ssid's)(是否扫描特定的SSID)
 * @return Number of discovered networks
 */
int8_t scanNetworks(bool async = false, bool show_hidden = false, uint8 channel = 0, uint8* ssid = NULL);
//实例代码 这只是部分代码 不能直接使用
//异步扫描
WiFi.scanNetworks(true);
// print out Wi-Fi network scan result uppon completion
int n = WiFi.scanComplete();
if(n >= 0){
  Serial.printf("%d network(s) found\n", n);
  for (int i = 0; i < n; i++){
     Serial.printf("%d: %s, Ch:%d (%ddBm) %s\n", i+1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "open" : "");
  }
  //打印一次结果之后把缓存中的数据清掉
  WiFi.scanDelete();
}

异步扫描周边有效网络并回调结果

/**
 * Starts scanning WiFi networks available in async mode
 * @param onComplete    the event handler executed when the scan is done
 * @param show_hidden   show hidden networks
  */
void scanNetworksAsync(std::function onComplete, bool show_hidden = false);
//实例代码
#include "ESP8266WiFi.h"
 
void prinScanResult(int networksFound)
{
  Serial.printf("%d network(s) found\n", networksFound);
  for (int i = 0; i < networksFound; i++)
  {
    Serial.printf("%d: %s, Ch:%d (%ddBm) %s\n", i + 1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "open" : "");
  }
}
 
 
void setup()
{
  Serial.begin(115200);
  Serial.println();
 
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);
 
  WiFi.scanNetworksAsync(prinScanResult);
}
 
 
void loop() {}
//应该会打印如下类似的显示
//5 network(s) found
//1: Tech_D005107, Ch:6 (-72dBm)
//2: HP-Print-A2-Photosmart 7520, Ch:6 (-79dBm)
//3: ESP_0B09E3, Ch:9 (-89dBm) open
//4: Hack-4-fun-net, Ch:9 (-91dBm)
//5: UPC Wi-Free, Ch:11 (-79dBm)

监测异步扫描结果

/**
 * called to get the scan state in Async mode(异步扫描的结果函数)
 * @return scan result or status
 *          -1 if scan not find
 *          -2 if scan not triggered
 */
int8_t scanComplete();

从内存中删掉最近扫描结果

/**
 * delete last scan result from RAM(从内存中删除最近的扫描结果)
 */
void scanDelete();

扫描结果方法

获取wifi网络名字

/**
 * Return the SSID discovered during the network scan.
 * @param i     specify from which network item want to get the information
 * @return       ssid string of the specified item on the networks scanned list
 */
String SSID(uint8_t networkItem);

获取wifi信号强度

/**
 * Return the RSSI of the networks discovered during the scanNetworks(信号强度)
 * @param i specify from which network item want to get the information
 * @return  signed value of RSSI of the specified item on the networks scanned list
 */
int32_t RSSI(uint8_t networkItem);

获取wifi网络加密方式

/**
 * Return the encryption type of the networks discovered during the scanNetworks(加密方式)
 * @param i specify from which network item want to get the information
 * @return  encryption type (enum wl_enc_type) of the specified item on the networks scanned list
 * ............ Values map to 802.11 encryption suites.....................
 *    AUTH_OPEN          ---->     ENC_TYPE_WEP  = 5,
 *    AUTH_WEP           ---->     ENC_TYPE_TKIP = 2,
 *    AUTH_WPA_PSK       ---->     ENC_TYPE_CCMP = 4,
 * ........... except these two, 7 and 8 are reserved in 802.11-2007.......
 *    AUTH_WPA2_PSK      ---->     ENC_TYPE_NONE = 7,
 *    AUTH_WPA_WPA2_PSK  ---->     ENC_TYPE_AUTO = 8
 */
uint8_t encryptionType(uint8_t networkItem);

获取wifi网络mac地址

/**
 * return MAC / BSSID of scanned wifi (物理地址)
 * @param i specify from which network item want to get the information
 * @return uint8_t * MAC / BSSID of scanned wifi
 */
uint8_t * BSSID(uint8_t networkItem);
 
/**
 * return MAC / BSSID of scanned wifi (物理地址)
 * @param i specify from which network item want to get the information
 * @return uint8_t * MAC / BSSID of scanned wifi
 */
String BSSIDstr(uint8_t networkItem);

获取整体网络信息名字

/**
 * loads all infos from a scanned wifi in to the ptr parameters
 * @param networkItem uint8_t
 * @param ssid  const char**
 * @param encryptionType uint8_t *
 * @param RSSI int32_t *
 * @param BSSID uint8_t **
 * @param channel int32_t *
 * @param isHidden bool *
 * @return (true if ok)
 */        
bool getNetworkInfo(uint8_t networkItem, String &ssid, uint8_t &encryptionType, int32_t &RSSI, uint8_t* &BSSID, int32_t &channel, bool &isHidden);
//注意:入参前面多数加了&,意味着调完函数后外面获取到详细信息;

获取整体网络型号通道

/**
 * return if the scanned wifi is Hidden (no SSID)(判断扫描到的wifi是否是隐藏wifi)
 * @param networkItem specify from which network item want to get the information
 * @return bool (true == hidden)
 */
bool isHidden(uint8_t networkItem);

实例操作

同步扫描

/**
 * Demo:
 *    STA模式下,演示同步扫描Scan wifi功能
 * @author 单片机菜鸟
 * @date 2019/09/03
 */
#include <ESP8266WiFi.h>
 
//以下三个定义为调试定义
#define DebugBegin(baud_rate)    Serial.begin(baud_rate)
#define DebugPrintln(message)    Serial.println(message)
#define DebugPrint(message)    Serial.print(message)
 
void setup() {
  //设置串口波特率,以便打印信息
  DebugBegin(115200);
  //延时5s 为了演示效果
  delay(5000);
  // 我不想别人连接我,只想做个站点
  WiFi.mode(WIFI_STA);
  //断开连接
  WiFi.disconnect();
  delay(100);
  DebugPrintln("Setup done");
}
 
void loop() {
  DebugPrintln("scan start");
  // 同步扫描,等待返回结果
  int n = WiFi.scanNetworks();
  DebugPrintln("scan done");
  if (n == 0){
    DebugPrintln("no networks found");
  }else{
    DebugPrint(n);
    DebugPrintln(" networks found");
    for (int i = 0; i < n; ++i){
      DebugPrint(i + 1);
      DebugPrint(": ");
      //打印wifi账号
      DebugPrint(WiFi.SSID(i));
      DebugPrint(",");
      DebugPrint(String("Ch:")+WiFi.channel(i));
      DebugPrint(",");
      DebugPrint(WiFi.isHidden(i)?"hide":"show");
      DebugPrint(" (");
      //打印wifi信号强度
      DebugPrint(WiFi.RSSI(i));
      DebugPrint("dBm");
      DebugPrint(")");
      //打印wifi加密方式
      DebugPrintln((WiFi.encryptionType(i) == ENC_TYPE_NONE)?"open":"*");
      delay(10);
    }
  }
  DebugPrintln("");
  // 延时5s之后再次扫描
  delay(5000);
}
效果演示

异步扫描2

/**
 * Demo:
 *    STA模式下,演示异步扫描Scan wifi功能
 * @author 单片机菜鸟
 * @date 2019/09/03
 */
#include <ESP8266WiFi.h>
 
//以下三个定义为调试定义
#define DebugBegin(baud_rate)    Serial.begin(baud_rate)
#define DebugPrintln(message)    Serial.println(message)
#define DebugPrint(message)    Serial.print(message)
 
/**
 * 打印扫描结果
 * @param networksFound 结果个数
 */
void prinScanResult(int networksFound){
  Serial.printf("%d network(s) found\n", networksFound);
  for (int i = 0; i < networksFound; i++)
  {
    Serial.printf("%d: %s, Ch:%d (%ddBm) %s\n", i + 1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "open" : "");
  }
}
 
void setup() {
  //设置串口波特率,以便打印信息
  DebugBegin(115200);
  //延时5s 为了演示效果
  delay(5000);
  // 我不想别人连接我,只想做个站点
  WiFi.mode(WIFI_STA);
  //断开连接
  WiFi.disconnect();
  delay(100);
  DebugPrintln("Setup done");
  Serial.print("\nScan start ... ");
  WiFi.scanNetworksAsync(prinScanResult);
}
 
void loop() {
}
效果演示

本笔记参考博哥博客,如果对你有帮助,可以给我赞赏哦!

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