add WiFi TX power control

Author: Links2004

libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.cpp

@@ -124,6 +124,23 @@ WiFiPhyMode_t ESP8266WiFiGenericClass::getPhyMode() {
     return (WiFiPhyMode_t) wifi_get_phy_mode();
 }
 
+/**
+ * set the output power of WiFi
+ * @param dBm max: +20.5dBm  min: 0dBm
+ */
+void ESP8266WiFiGenericClass::setOutputPower(float_t dBm) {
+
+    if(dBm > 20.5) {
+        dBm = 20.5;
+    } else if(dBm < 0) {
+        dBm = 0;
+    }
+
+    uint8_t val = (dBm*4.0f);
+    system_phy_set_max_tpw(val);
+}
+
+
 /**
  * store WiFi config in SDK flash area
  * @param persistent

libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.h

@@ -46,6 +46,8 @@ class ESP8266WiFiGenericClass {
         bool setPhyMode(WiFiPhyMode_t mode);
         WiFiPhyMode_t getPhyMode();
 
+        void setOutputPower(float_t dBm);
+
         void persistent(bool persistent);
 
         bool mode(WiFiMode_t);