Add ESP32 optional brownout disable

Add ESP32 brownout disable for weak onboard LDO's - eventually you'll need to change the LDO to a better one.

libesp32/ESP32-to-ESP8266-compat/src/esp8266toEsp32.cpp

@@ -109,3 +109,12 @@ uint32_t ESP_getSketchSize(void)
   }
   return sketchsize;
 }
+
+#include "soc/soc.h"
+#include "soc/rtc_cntl_reg.h"
+
+void DisableBrownout(void)
+{
+  // https://github.com/espressif/arduino-esp32/issues/863#issuecomment-347179737
+  WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0);  // Disable brownout detector
+}

libesp32/ESP32-to-ESP8266-compat/src/esp8266toEsp32.h

@@ -43,6 +43,7 @@ uint32_t ESP_getFlashChipId();
 uint32_t ESP_getChipId();
 String String_ESP_getChipId();
 uint32_t ESP_getSketchSize();
+void DisableBrownout(void);
 
 // Analog
 inline void analogWrite(uint8_t pin, int val)

tasmota/tasmota.ino

@@ -192,6 +192,12 @@ void setup(void)
 {
   global_state.data = 3;  // Init global state (wifi_down, mqtt_down) to solve possible network issues
 
+#ifdef ESP32
+#ifdef DISABLE_BROWNOUT
+  DisableBrownout();
+#endif
+#endif
+
   RtcRebootLoad();
   if (!RtcRebootValid()) {
     RtcReboot.fast_reboot_count = 0;