#include <TimerOne.h>
int interval=1000000;

bool toggle = false;
 
void test ()
{
  if(digitalRead(10)==LOW)
   digitalWrite(10, HIGH);
  else
   digitalWrite(10, LOW);
}

void setup() {
pinMode(10, OUTPUT);
Timer1.initialize(200000);
Timer1.attachInterrupt(test);


}

void loop() {
  if(digitalRead(2)== LOW)
  toggle = !toggle;

  if(toggle)
   interval = 500000;
  else
   interval = 1000000;

   Timer1.setPeriod(interval);
}