说明：  89C2051单片机用于电动车调速控制电路源程序。自由转动，控制是否过流，过流调速信号控制，调速信号，调速信号电压。
(89C2051 microcontroller circuit for electric vehicle speed control source. Free rotation, the control is over-current, over-current control speed signal, speed signal, speed signal voltage.)