Today we have successfully controlled LED on D1 mini. D1 mini is cheap chip from China, which has wifi connectivity. You can program it via Arduino IDE. There is a simple code for built in LED control. LED is connected to port D4 of D1 mini.
void setup() {
// put your setup code here, to run once:
pinMode(D4, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
digitalWrite(D4, HIGH);
delay(1000);
digitalWrite(D4, LOW);
delay(1000);
}