Esp8266 使用 Arduino 开发（二）

Esp8266 使用 Arduino 开发（二）

这一次讲的时ESP8266WiFiScan.h文件，用来搜索可用WiFi。

int8_t scanNetworks(bool async = false, bool show_hidden = false);

int8_t scanComplete();       //  查看是否搜索结束
void scanDelete();              //  删除上一次搜索的结果

// scan result
bool getNetworkInfo(uint8_t networkItem, String &ssid, uint8_t &encryptionType, int32_t &RSSI, uint8_t* &BSSID, int32_t &channel, bool &isHidden);

String SSID(uint8_t networkItem);   //  WiFi 的名称
uint8_t encryptionType(uint8_t networkItem);
int32_t RSSI(uint8_t networkItem);  //   信号强度
uint8_t * BSSID(uint8_t networkItem);  //  
String BSSIDstr(uint8_t networkItem);
int32_t channel(uint8_t networkItem);
bool isHidden(uint8_t networkItem);

使用时只需调用WiFi.scanNetworks();     ESP8266便会搜索WiFI，并将搜索的结果存到数组中。
官方例程在调用WiFi.scanNetworks();之前先调用了

WiFi.mode(WIFI_STA);
WiFi.disconnect();

实际上可以不重复调用，因为在scanNetworks();这个函数中官方已经调用过了：

int8_t ESP8266WiFiScanClass::scanNetworks(bool async, bool show_hidden) {
    if(ESP8266WiFiScanClass::_scanStarted) {
        return WIFI_SCAN_RUNNING;
    }

    ESP8266WiFiScanClass::_scanAsync = async;

    WiFi.enableSTA(true);
                      //  使能STA模式
            
    int status = wifi_station_get_connect_status();
    if(status != STATION_GOT_IP && status != STATION_IDLE) {
        WiFi.disconnect(false);
                // 断开已连接的WiFi
    }

    scanDelete();
                                   // 删除 上一次的搜索结果

    struct scan_config config;
    config.ssid = 0;
    config.bssid = 0;
    config.channel = 0;
    config.show_hidden = show_hidden;
    if(wifi_station_scan(&config, reinterpret_cast(&ESP8266WiFiScanClass::_scanDone))) {
        ESP8266WiFiScanClass::_scanComplete = false;
        ESP8266WiFiScanClass::_scanStarted = true;

        if(ESP8266WiFiScanClass::_scanAsync) {
            delay(0); // time for the OS to trigger the scan
            return WIFI_SCAN_RUNNING;
        }

        esp_yield();
        return ESP8266WiFiScanClass::_scanCount;
    } else {
        return WIFI_SCAN_FAILED;
    }

}

想要查看第一个WiFi的SSID，只需调用WiFi.SSID(0);想查看其他的参数同理。

#include 

#define LED        2
#define KEY        4

void setup() {
// put your setup code here, to run once:
  uint8_t n = 0;
  uint8_t i = 0;

  Serial.begin(115200);

  pinMode(LED, OUTPUT);
  pinMode(KEY, INPUT);

  Serial.println("scan start......");

  n = WiFi.scanNetworks();

  if(n == 0){
    Serial.println("no networks found");
  }
  else{
    Serial.print(n);
    Serial.println(" networks found");

    for(i=0; i
      Serial.print(i + 1);
      Serial.print(": ");
      Serial.print(WiFi.SSID(i));
      Serial.print(" (");
      Serial.print(WiFi.RSSI(i));
      Serial.print(")");
      Serial.println((WiFi.encryptionType(i) == ENC_TYPE_NONE)?" ":"*");

      delay(10);
    }    
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(500);
  Serial.print(".");
}

`