Fixed the ability to change CHANNEL (#7154)

* Removed option to change CHANNEL

* Revert "Removed option to change CHANNEL"

This reverts commit b2ec27d.

* Fixed the ability to change CHANNEL

* WiFi scan only on selected channel

libraries/ESP32/examples/ESPNow/Basic/Master/Master.ino

@@ -31,6 +31,7 @@
 
 #include <esp_now.h>
 #include <WiFi.h>
+#include <esp_wifi.h> // only for esp_wifi_set_channel()
 
 // Global copy of slave
 esp_now_peer_info_t slave;
@@ -55,7 +56,7 @@ void InitESPNow() {
 
 // Scan for slaves in AP mode
 void ScanForSlave() {
-  int8_t scanResults = WiFi.scanNetworks();
+  int16_t scanResults = WiFi.scanNetworks(false, false, false, 300, CHANNEL); // Scan only on one channel
   // reset on each scan
   bool slaveFound = 0;
   memset(&slave, 0, sizeof(slave));
@@ -222,9 +223,11 @@ void setup() {
   Serial.begin(115200);
   //Set device in STA mode to begin with
   WiFi.mode(WIFI_STA);
+  esp_wifi_set_channel(CHANNEL, WIFI_SECOND_CHAN_NONE);
   Serial.println("ESPNow/Basic/Master Example");
   // This is the mac address of the Master in Station Mode
   Serial.print("STA MAC: "); Serial.println(WiFi.macAddress());
+  Serial.print("STA CHANNEL "); Serial.println(WiFi.channel());
   // Init ESPNow with a fallback logic
   InitESPNow();
   // Once ESPNow is successfully Init, we will register for Send CB to

libraries/ESP32/examples/ESPNow/Basic/Slave/Slave.ino

@@ -57,6 +57,7 @@ void configDeviceAP() {
     Serial.println("AP Config failed.");
   } else {
     Serial.println("AP Config Success. Broadcasting with AP: " + String(SSID));
+    Serial.print("AP CHANNEL "); Serial.println(WiFi.channel());
   }
 }