Use the IO port triangle to trigger the distance measurement, and give at least 10 our high-level signals; the module automatically sends 8 40 khz square waves to automatically detect whether there is a signal return; there is a signal return, and a high level is output through the IO port echo, The duration of the high level is the time from emission to return of the ultrasonic wave.The IO port trigger is used to trigger the distance measurement to give a high level signal of at least 10us; the module automatically sends 8 40KHz square waves to detect whether there is a signal return; there is a signal return, and one is output through the IO port echo High level, high level duration is the time from emission to return of ultrasound.