说明：  朗顿科技的STC8952开发板原理图，支持多种外设扩展：USB扩展板，CAN总线扩展板，A/D,D/A扩展板。
(Langdon Technology STC8952 development board schematics to support expansion of a variety of peripherals: USB expansion board, CAN bus expansion boards, A/D, D/A expansion board.)