说明：  详细介绍了周立功can卡的接口函数，对停产板卡进行了标注，增加了usbcan-4e-u板卡部分及定时发送功能说明
(The interface function of Zhou Li Gong can card is introduced in detail, and the stop board card is annotated, and the function of the usbcan-4e-u card part and the timing transmission function is added.)