How do you plan to solve it?
R-320 Ohms
connect to digital GPIO pin 7
int pin =7;
int ONTIME = 400;
int OFFTIME = 800;
void setup()
{
pinMode(pin, OUTPUT);
}
void loop()
{
digitalWrite(pin, HIGH);
delay(ONTIME);
digitalWrite(pin, LOW);
delay(OFFTIME);
}