基于ｖｈｄｌ的乒乓球比赛设计：用发光二极管作为球，按键为发球和击球，２１分为一局。有５个发光二极管，第三个当做网，过了网才可击球，否则对方加一分，直至有一方达到２１分比赛结束。-Vhdl-based design of table tennis: the light-emitting diode as the ball, the ball and hitting the key for 21 points For one council. 5 light-emitting diode, t