inserir valores de carimbo de data/hora em etapas de 3 minutos

CREATE PROCEDURE myProc(IN t1 timestamp, IN t2 timestamp)
BEGIN

  WHILE t1 <= t2 DO
INSERT INTO test (ts) Values (t1)  ;
    SET t1 = DATE_ADD(t1, INTERVAL 3 MINUTE);
  END WHILE;
END;


CALL myProc(now(), ADDDATE(NOW(), INTERVAL 15 MINUTE));

SET StartTS  = StartTS  + INTERVAL 3 MINUTE;

SET StartTS  = ADDDATE(StartTS, INTERVAL 3 MINUTE);