void t1Callback() { Serial.print("t1: "); Serial.println(millis()); if (t1.isFirstIteration()) { runner.addTask(t3); t3.enable(); Serial.println("t1: enabled t3 and added to the chain"); } if (t1.isLastIteration()) { t3.disable(); runner.deleteTask(t3); t2.setInterval(500); Serial.println("t1: disable t3 and delete it from the chain. t2 interval set to 500"); } }