利用加強的PWM模組輸出半橋式PWM輸出，並設定適當的空乏時間，同時開啟自動關閉功能，當RB0觸發時檢查蜂鳴器是否運作正常，這是PIC184520的源碼-The use of enhanced PWM module output half-bridge PWM output, and set the appropriate depletion time and open self-closing feature, when Rb0 trigger buzzer when the normal f