Blynk mailbox sensor (mosfet + reed switch + WeMos)

mailboxWatcher.ino

#include <SimpleTimer.h>
//#define BLYNK_PRINT Serial    // Comment this out to disable prints and save space
#include <BlynkSimpleEsp8266.h>

extern "C" {
  uint16 readvdd33(void);
}

char auth[] = "fromBlynkApp";
const char* ssid = "ssid";
const char* pw = "pw";
const int gate = 5;   // Mosfet gate on WeMos D1 Mini pin D1 (formerly D4... was draining my battery when off!)

SimpleTimer timer;

void setup() {
  pinMode(gate, OUTPUT);
  digitalWrite(gate, LOW);

  Serial.begin(9600);
  Blynk.begin(auth, ssid, pw);

  while (Blynk.connect() == false) {
    // Wait until connected
  }
  
  float vdd = readvdd33() / 1000.0;
  //Blynk.notify(WiFi.RSSI());
  Blynk.notify(String("You've got mail! (batt=") + vdd + "v)");
  timer.setTimeout(1000L, shutDown);
}

void loop() {
  Blynk.run();
  timer.run();
}

void shutDown() {
  digitalWrite(gate, HIGH);
}