In idle mode, the cpu has no clock, but the timer adc converter can work normally. In 1876, British surgeon Thorgar patented a timing device for controlling the switching of gas street lights. It uses a mechanical clock to drive a switch to control the gas valve. At first, the clockwork was wound once a week, but after the introduction of electric clocks in 1918, winding was no longer necessary. With the improvement of living standards, timers are becoming more and more widely used. For example, for the timing control of water boilers and water heaters, there are high-power timers that can start up and shut down at scheduled times to achieve energy-saving, safe and healthy use.